Publications by authors named "Ergun Y Uc"

45 Publications

Approach to Cognitive Impairment in Parkinson's Disease.

Neurotherapeutics 2020 10 17;17(4):1495-1510. Epub 2020 Nov 17.

Department of Neurology, Carver College of Medicine, University of Iowa, 200 Hawkins Drive-2RCP, Iowa City, Iowa, 52242, USA.

Cognitive dysfunction is common in Parkinson's disease (PD) and predicts poor clinical outcomes. It is associated primarily with pathologic involvement of basal forebrain cholinergic and prefrontal dopaminergic systems. Impairments in executive functions, attention, and visuospatial abilities are its hallmark features with eventual involvement of memory and other domains. Subtle symptoms in the premotor and early phases of PD progress to mild cognitive impairment (MCI) which may be present at the time of diagnosis. Eventually, a large majority of PD patients develop dementia with advancing age and longer disease duration, which is usually accompanied by immobility, hallucinations/psychosis, and dysautonomia. Dopaminergic medications and deep brain stimulation help motor dysfunction, but may have potential cognitive side effects. Central acetylcholinesterase inhibitors, and possibly memantine, provide modest and temporary symptomatic relief for dementia, although there is no evidence-based treatment for MCI. There is no proven disease-modifying treatment for cognitive impairment in PD. The symptomatic and disease-modifying role of physical exercise, cognitive training, and neuromodulation on cognitive impairment in PD is under investigation. Multidisciplinary approaches to cognitive impairment with effective treatment of comorbidities, proper rehabilitation, and maintenance of good support systems in addition to pharmaceutical treatment may improve the quality of life of the patients and caregivers.
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http://dx.doi.org/10.1007/s13311-020-00963-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851260PMC
October 2020

Cerebellar Transcranial Direct Current Stimulation in People with Parkinson's Disease: A Pilot Study.

Brain Sci 2020 Feb 11;10(2). Epub 2020 Feb 11.

Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242, USA.

People with Parkinson's disease (PwPD) often experience gait and balance problems that substantially impact their quality of life. Pharmacological, surgical, and rehabilitative treatments have limited effectiveness and many PwPD continue to experience gait and balance impairment. Transcranial direct current stimulation (tDCS) may represent a viable therapeutic adjunct. The effects of lower intensity tDCS (2 mA) over frontal brain areas, in unilateral and bilateral montages, has previously been explored; however, the effects of lower and higher intensity cerebellar tDCS (2 mA and 4 mA, respectively) on gait and balance has not been investigated. Seven PwPD underwent five cerebellar tDCS conditions (sham, unilateral 2 mA, bilateral 2 mA, unilateral 4 mA, and bilateral 4 mA) for 20 min. After a 10 min rest, gait and balance were tested. The results indicated that the bilateral 4 mA cerebellar tDCS condition had a significantly higher Berg Balance Scale score compared to sham. This study provides preliminary evidence that a single session of tDCS over the cerebellum, using a bilateral configuration at a higher intensity (4 mA), significantly improved balance performance. This intensity and cerebellar configuration warrants future investigation in larger samples and over repeated sessions.
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http://dx.doi.org/10.3390/brainsci10020096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071613PMC
February 2020

Driving in Parkinson Disease.

Clin Geriatr Med 2020 02 6;36(1):141-148. Epub 2019 Sep 6.

Department of Neurology, University of Iowa, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA; Neurology Service, Veterans Affairs Medical Center, 601 Highway 6 W, Iowa City, IA 52246, USA. Electronic address:

Driving is impaired in most patients with Parkinson disease because of motor, cognitive, and visual dysfunction. Driving impairments in Parkinson disease may increase the risk of crashes and result in early driving cessation with loss of independence. Drivers with Parkinson disease should undergo comprehensive evaluations to determine fitness to drive with periodic follow-up evaluations as needed. Research in rehabilitation of driving and automation to maintain independence of patients with Parkinson disease is in progress.
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http://dx.doi.org/10.1016/j.cger.2019.09.007DOI Listing
February 2020

Driving impairment and crash risk in Parkinson disease: A systematic review and meta-analysis.

Neurology 2018 09 3;91(10):e906-e916. Epub 2018 Aug 3.

From the Faculty of Education and Health (T.T., D.P., C.M.), University of Greenwich, London, UK; Department of Neuroscience (M.S.), University of Padova; National Research Council (N.V.), Neurosciences Department, Aging Branch, Padova, Italy; Department of Psychiatry (A.F.C.), University of Toronto; Centre for Addiction & Mental Health (A.F.C.), Toronto, Canada; Physiotherapy Department (B.S.), South London and Maudsley NHS Foundation Trust, London; Department of Psychological Medicine (B.S.), King's College, De Crespigny Park, London, UK; Department of Neurology (E.Y.U.), Carver College of Medicine, University of Iowa, Iowa City; and Neurology Service (E.Y.U.), Iowa City Veterans Affairs Medical Center, IA.

Objectives: To provide the best possible evidence base for guiding driving decisions in Parkinson disease (PD), we performed a meta-analysis comparing patients with PD to healthy controls (HCs) on naturalistic, on-the-road, and simulator driving outcomes.

Methods: Seven major databases were systematically searched (to January 2018) for studies comparing patients with PD to HCs on overall driving performance, with data analyzed using random-effects meta-analysis.

Results: Fifty studies comprising 5,410 participants (PD = 1,955, HC = 3,455) met eligibility criteria. Analysis found the odds of on-the-road test failure were 6.16 (95% confidence interval [CI] 3.79-10.03) times higher and the odds of simulator crashes 2.63 (95% CI 1.64-4.22) times higher for people with PD, with poorer overall driving ratings also observed (standardized mean differences from 0.50 to 0.67). However, self-reported real-life crash involvement did not differ between people with PD and HCs (odds ratio = 0.84, 95% CI 0.57-1.23, = 0.38). Findings remained unchanged after accounting for any differences in age, sex, and driving exposure, and no moderating influence of disease severity was found.

Conclusions: Our findings provide persuasive evidence for substantive driving impairment in PD, but offer little support for mandated PD-specific relicensure based on self-reported crash data alone, and highlight the need for objective measures of crash involvement.
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http://dx.doi.org/10.1212/WNL.0000000000006132DOI Listing
September 2018

Cognitive impairment in Parkinson's disease: a report from a multidisciplinary symposium on unmet needs and future directions to maintain cognitive health.

NPJ Parkinsons Dis 2018 26;4:19. Epub 2018 Jun 26.

Illinois, USA.

People with Parkinson's disease (PD) and their care partners frequently report cognitive decline as one of their greatest concerns. Mild cognitive impairment affects approximately 20-50% of people with PD, and longitudinal studies reveal dementia in up to 80% of PD. Through the Parkinson's Disease Foundation Community Choice Research Award Program, the PD community identified maintaining cognitive function as one of their major unmet needs. In response, a working group of experts across multiple disciplines was organized to evaluate the unmet needs, current challenges, and future opportunities related to cognitive impairment in PD. Specific conference goals included defining the current state in the field and gaps regarding cognitive issues in PD from patient, care partner, and healthcare professional viewpoints; discussing non-pharmacological interventions to help maintain cognitive function; forming recommendations for what people with PD can do at all disease stages to maintain cognitive health; and proposing ideas for how healthcare professionals can approach cognitive changes in PD. This paper summarizes the discussions of the conference, first by addressing what is currently known about cognitive dysfunction in PD and discussing several non-pharmacological interventions that are often suggested to people with PD. Second, based on the conference discussions, we provide considerations for people with PD for maintaining cognitive health and for healthcare professionals and care partners when working with people with PD experiencing cognitive impairment. Furthermore, we highlight key issues and knowledge gaps that need to be addressed in order to advance research in cognition in PD and improve clinical care.
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http://dx.doi.org/10.1038/s41531-018-0055-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6018742PMC
June 2018

Longitudinal decline of driving safety in Parkinson disease.

Neurology 2017 Nov 11;89(19):1951-1958. Epub 2017 Oct 11.

From the Departments of Neurology (E.Y.U., M.R., S.W.A.) and Biostatistics (A.M.J.O., J.D.D.), University of Iowa; Neurology Service (E.Y.U.) and Comprehensive Access and Delivery Research & Evaluation (A.M.J.O.), Veterans Affairs Medical Center, Iowa City, IA; and Department of Neurology (M.R.), University of Nebraska, Omaha.

Objective: To longitudinally assess and predict on-road driving safety in Parkinson disease (PD).

Methods: Drivers with PD (n = 67) and healthy controls (n = 110) drove a standardized route in an instrumented vehicle and were invited to return 2 years later. A professional driving expert reviewed drive data and videos to score safety errors.

Results: At baseline, drivers with PD performed worse on visual, cognitive, and motor tests, and committed more road safety errors compared to controls (median PD 38.0 vs controls 30.5; < 0.001). A smaller proportion of drivers with PD returned for repeat testing (42.8% vs 62.7%; < 0.01). At baseline, returnees with PD made fewer errors than nonreturnees with PD (median 34.5 vs 40.0; < 0.05) and performed similar to control returnees (median 33). Baseline global cognitive performance of returnees with PD was better than that of nonreturnees with PD, but worse than for control returnees ( < 0.05). After 2 years, returnees with PD showed greater cognitive decline and larger increase in error counts than control returnees (median increase PD 13.5 vs controls 3.0; < 0.001). Driving error count increase in the returnees with PD was predicted by greater error count and worse visual acuity at baseline, and by greater interval worsening of global cognition, Unified Parkinson's Disease Rating Scale activities of daily living score, executive functions, visual processing speed, and attention.

Conclusions: Despite drop out of the more impaired drivers within the PD cohort, returning drivers with PD, who drove like controls without PD at baseline, showed many more driving safety errors than controls after 2 years. Driving decline in PD was predicted by baseline driving performance and deterioration of cognitive, visual, and functional abnormalities on follow-up.
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http://dx.doi.org/10.1212/WNL.0000000000004629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679414PMC
November 2017

Separating the effect of reward from corrective feedback during learning in patients with Parkinson's disease.

Cogn Affect Behav Neurosci 2017 06;17(3):678-695

Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, 52242, USA.

Parkinson's disease (PD) is associated with procedural learning deficits. Nonetheless, studies have demonstrated that reward-related learning is comparable between patients with PD and controls (Bódi et al., Brain, 132(9), 2385-2395, 2009; Frank, Seeberger, & O'Reilly, Science, 306(5703), 1940-1943, 2004; Palminteri et al., Proceedings of the National Academy of Sciences of the United States of America, 106(45), 19179-19184, 2009). However, because these studies do not separate the effect of reward from the effect of practice, it is difficult to determine whether the effect of reward on learning is distinct from the effect of corrective feedback on learning. Thus, it is unknown whether these group differences in learning are due to reward processing or learning in general. Here, we compared the performance of medicated PD patients to demographically matched healthy controls (HCs) on a task where the effect of reward can be examined separately from the effect of practice. We found that patients with PD showed significantly less reward-related learning improvements compared to HCs. In addition, stronger learning of rewarded associations over unrewarded associations was significantly correlated with smaller skin-conductance responses for HCs but not PD patients. These results demonstrate that when separating the effect of reward from the effect of corrective feedback, PD patients do not benefit from reward.
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http://dx.doi.org/10.3758/s13415-017-0505-0DOI Listing
June 2017

Use, maintenance and dose effects of cognitive speed of processing training in Parkinson's disease.

Int J Neurosci 2017 Oct 20;127(10):841-848. Epub 2016 Dec 20.

a School of Aging Studies University of South Florida , Tampa , FL , USA.

Introduction: Recent research indicated that cognitive speed of processing training (SPT) improved Useful Field of View (UFOV) among individuals with Parkinson's disease (PD). The effects of SPT in PD have not been further examined. The objectives of the current study were to investigate use, maintenance and dose effects of SPT among individuals with PD.

Methods: Participants who were randomized to SPT or a delayed control group completed the UFOV at a six-month follow-up visit. Use of SPT was monitored across the six-month study period. Regression explored factors affecting SPT use. Mixed effect models were conducted to examine the durability of training gains among those randomized to SPT (n = 44), and training dose effects among the entire sample (n = 87).

Results: The majority of participants chose to continue to use SPT (52%). Those randomized to SPT maintained improvements in UFOV performance. A significant dose effect of SPT was evident such that more hours of training were associated with greater UFOV performance improvements. The cognitive benefits derived from SPT in PD may be maintained for up to three months.

Conclusion: Future research should determine how long gains endure and explore if such training gains transfer.
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http://dx.doi.org/10.1080/00207454.2016.1269088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8284743PMC
October 2017

Establishing an evidence-base framework for driving rehabilitation in Parkinson's disease: A systematic review of on-road driving studies.

NeuroRehabilitation 2015 ;37(1):35-52

Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.

Background: Individuals with Parkinson's disease (PD) experience problems with on-road driving that can be targeted in driving rehabilitation programs.

Objective: To provide a framework for driving rehabilitation in PD by identifying the critical on-road driving impairments and their associated visual, cognitive, and motor deficits.

Methods: We conducted a systematic review of the literature on on-road driving and naturalistic driving practices in PD. Relevant databases including Pubmed, Medline, PsychINFO, ISI Web of Science, Cochrane library, and ClinicalTrials.gov, were reviewed using the key words Parkinson's disease, on-road driving, naturalistic driving, and their related entry words. On-road driving skills were mapped onto an existing theoretic model of operational, tactical, and strategic levels. The on-road and off-road cognitive, motor, and visual predictors of global on-road driving were summarized.

Results: Twenty-seven studies were included. All but one study were prospective and Class II studies according to the American Academy of Neurology Classification Criteria. Participants were on average 68 years old and in the mild to moderate stages of PD. Drivers with PD were more likely to fail a driving assessment compared to age- and gender-matched controls. Compared with controls, drivers with PD experienced difficulties on all levels of driving skill. However, the compensation strategies on the strategic level showed that drivers with PD were aware of their diminished driving skills on the operational and strategic levels. Operational and tactical on-road driving skills best predicted global on-road driving. A combination of visual, cognitive, and motor deficits underlie impaired on-road driving performance in PD.

Conclusion: Driving rehabilitation strategies for individuals with PD should include training of operational and tactical driving skills or indirect comprehensive training program of visual, cognitive, and motor skills.
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http://dx.doi.org/10.3233/NRE-151239DOI Listing
June 2016

Gestures make memories, but what kind? Patients with impaired procedural memory display disruptions in gesture production and comprehension.

Front Hum Neurosci 2014 13;8:1054. Epub 2015 Jan 13.

Neuroscience Graduate Program, University of Iowa Iowa City, IA, USA ; DeLTA Center, University of Iowa Iowa City, IA, USA ; Department of Neurology, University of Iowa Iowa City, IA, USA ; Department of Communication Sciences and Disorders, University of Iowa Iowa City, IA, USA.

Hand gesture, a ubiquitous feature of human interaction, facilitates communication. Gesture also facilitates new learning, benefiting speakers and listeners alike. Thus, gestures must impact cognition beyond simply supporting the expression of already-formed ideas. However, the cognitive and neural mechanisms supporting the effects of gesture on learning and memory are largely unknown. We hypothesized that gesture's ability to drive new learning is supported by procedural memory and that procedural memory deficits will disrupt gesture production and comprehension. We tested this proposal in patients with intact declarative memory, but impaired procedural memory as a consequence of Parkinson's disease (PD), and healthy comparison participants with intact declarative and procedural memory. In separate experiments, we manipulated the gestures participants saw and produced in a Tower of Hanoi (TOH) paradigm. In the first experiment, participants solved the task either on a physical board, requiring high arching movements to manipulate the discs from peg to peg, or on a computer, requiring only flat, sideways movements of the mouse. When explaining the task, healthy participants with intact procedural memory displayed evidence of their previous experience in their gestures, producing higher, more arching hand gestures after solving on a physical board, and smaller, flatter gestures after solving on a computer. In the second experiment, healthy participants who saw high arching hand gestures in an explanation prior to solving the task subsequently moved the mouse with significantly higher curvature than those who saw smaller, flatter gestures prior to solving the task. These patterns were absent in both gesture production and comprehension experiments in patients with procedural memory impairment. These findings suggest that the procedural memory system supports the ability of gesture to drive new learning.
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http://dx.doi.org/10.3389/fnhum.2014.01054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4292316PMC
January 2015

Phase I/II randomized trial of aerobic exercise in Parkinson disease in a community setting.

Neurology 2014 Jul 2;83(5):413-25. Epub 2014 Jul 2.

From the Departments of Neurology (E.Y.U., T.R.T., M.R., S.R.N., J.B., S.W.A.), Internal Medicine (K.C.D., J.N.K.), Radiology (V.M.), Biostatistics (J.D.D., D.R.B.), Psychology (M.W.V.), and Health and Human Physiology (W.G.D.), University of Iowa, Iowa City; Neurology Service (E.Y.U., T.R.T., S.R.N.), Veterans Affairs Medical Center, Iowa City, IA; Department of Neurology (S.M., T.J.G.), University of Washington, Seattle; and Department of Psychology (A.F.K.), Beckman Institute, University of Illinois, Urbana-Champaign.

Objectives: To (1) investigate effects of aerobic walking on motor function, cognition, and quality of life in Parkinson disease (PD), and (2) compare safety, tolerability, and fitness benefits of different forms of exercise intervention: continuous/moderate intensity vs interval/alternating between low and vigorous intensity, and individual/neighborhood vs group/facility setting.

Methods: Initial design was a 6-month, 2 × 2 randomized trial of different exercise regimens in independently ambulatory patients with PD. All arms were required to exercise 3 times per week, 45 minutes per session.

Results: Randomization to group/facility setting was not feasible because of logistical factors. Over the first 2 years, we randomized 43 participants to continuous or interval training. Because preliminary analyses suggested higher musculoskeletal adverse events in the interval group and lack of difference between training methods in improving fitness, the next 17 participants were allocated only to continuous training. Eighty-one percent of 60 participants completed the study with a mean attendance of 83.3% (95% confidence interval: 77.5%-89.0%), exercising at 46.8% (44.0%-49.7%) of their heart rate reserve. There were no serious adverse events. Across all completers, we observed improvements in maximum oxygen consumption, gait speed, Unified Parkinson's Disease Rating Scale sections I and III scores (particularly axial functions and rigidity), fatigue, depression, quality of life (e.g., psychological outlook), and flanker task scores (p < 0.05 to p < 0.001). Increase in maximum oxygen consumption correlated with improvements on the flanker task and quality of life (p < 0.05).

Conclusions: Our preliminary study suggests that aerobic walking in a community setting is safe, well tolerated, and improves aerobic fitness, motor function, fatigue, mood, executive control, and quality of life in mild to moderate PD.

Classification Of Evidence: This study provides Class IV evidence that in patients with PD, an aerobic exercise program improves aerobic fitness, motor function, fatigue, mood, and cognition.
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http://dx.doi.org/10.1212/WNL.0000000000000644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132568PMC
July 2014

Cognitive impairment and dementia in Parkinson's disease: practical issues and management.

Mov Disord 2014 Apr;29(5):663-72

Istanbul University, Istanbul Faculty of Medicine, Department of Neurology, Behavioral Neurology and Movement Disorders Unit, Istanbul, Turkey.

Cognitive impairment and dementia pose particular challenges in the management of patients with Parkinson's disease (PD). Decision-making capacity can render patients vulnerable in a way that requires careful ethical considerations by clinicians with respect to medical decision making, research participation, and public safety. Clinicians should discuss how future decisions will be made as early in the disease course as possible. Because of cognitive, visual, and motor impairments, PD may be associated with unsafe driving, leading to early driving cessation in many. DBS of the STN and, to a lesser degree, globus pallidus interna (GPi) has consistently been associated with decreased verbal fluency, but significant global cognitive decline is usually not observed in patients who undergo rigorous selection. There are some observations suggesting lesser cognitive decline in GPi DBS than STN DBS, but further research is required. Management of PD dementia (PDD) patients involves both pharmacological and nonpharmacological measures. Patients with PDD should be offered treatment with a cholinesterase inhibitor taking into account expected benefits and potential risks. Treatment with neuroleptics may be necessary to treat psychosis; classical neuroleptics, as well as risperidone and olanzapine, should be avoided. Quetiapine might be considered first-line treatment because it does not need special monitoring, although the strongest evidence for efficacy exists for clozapine. Evidence from randomized, controlled studies in the PDD population is lacking; selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors may be used to treat depressive features. Clonazepam or melatonin may be useful in the treatment of rapid eye movement behavior disorder.
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http://dx.doi.org/10.1002/mds.25870DOI Listing
April 2014

A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit.

JAMA Neurol 2014 May;71(5):543-52

Columbia University Medical Center, Neurological Institute, New York, New York.

Importance: Coenzyme Q10 (CoQ10), an antioxidant that supports mitochondrial function, has been shown in preclinical Parkinson disease (PD) models to reduce the loss of dopamine neurons, and was safe and well tolerated in early-phase human studies. A previous phase II study suggested possible clinical benefit.

Objective: To examine whether CoQ10 could slow disease progression in early PD.

Design, Setting, And Participants: A phase III randomized, placebo-controlled, double-blind clinical trial at 67 North American sites consisting of participants 30 years of age or older who received a diagnosis of PD within 5 years and who had the following inclusion criteria: the presence of a rest tremor, bradykinesia, and rigidity; a modified Hoehn and Yahr stage of 2.5 or less; and no anticipated need for dopaminergic therapy within 3 months. Exclusion criteria included the use of any PD medication within 60 days, the use of any symptomatic PD medication for more than 90 days, atypical or drug-induced parkinsonism, a Unified Parkinson's Disease Rating Scale (UPDRS) rest tremor score of 3 or greater for any limb, a Mini-Mental State Examination score of 25 or less, a history of stroke, the use of certain supplements, and substantial recent exposure to CoQ10. Of 696 participants screened, 78 were found to be ineligible, and 18 declined participation.

Interventions: The remaining 600 participants were randomly assigned to receive placebo, 1200 mg/d of CoQ10, or 2400 mg/d of CoQ10; all participants received 1200 IU/d of vitamin E.

Main Outcomes And Measures: Participants were observed for 16 months or until a disability requiring dopaminergic treatment. The prospectively defined primary outcome measure was the change in total UPDRS score (Parts I-III) from baseline to final visit. The study was powered to detect a 3-point difference between an active treatment and placebo.

Results: The baseline characteristics of the participants were well balanced, the mean age was 62.5 years, 66% of participants were male, and the mean baseline total UPDRS score was 22.7. A total of 267 participants required treatment (94 received placebo, 87 received 1200 mg/d of CoQ10, and 86 received 2400 mg/d of CoQ10), and 65 participants (29 who received placebo, 19 who received 1200 mg/d of CoQ10, and 17 who received 2400 mg/d of CoQ10) withdrew prematurely. Treatments were well tolerated with no safety concerns. The study was terminated after a prespecified futility criterion was reached. At study termination, both active treatment groups showed slight adverse trends relative to placebo. Adjusted mean changes (worsening) in total UPDRS scores from baseline to final visit were 6.9 points (placebo), 7.5 points (1200 mg/d of CoQ10; P = .49 relative to placebo), and 8.0 points (2400 mg/d of CoQ10; P = .21 relative to placebo).

Conclusions And Relevance: Coenzyme Q10 was safe and well tolerated in this population, but showed no evidence of clinical benefit.

Trial Registration: clinicaltrials.gov Identifier: NCT00740714.
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http://dx.doi.org/10.1001/jamaneurol.2014.131DOI Listing
May 2014

On-road driving impairments in Huntington disease.

Neurology 2014 Mar 12;82(11):956-62. Epub 2014 Feb 12.

From the Department of Physical Therapy (H.D.), College of Allied Health Sciences, Georgia Regents University, Augusta, GA; Department of Rehabilitation Sciences (H.D., A.N., W.D.W.), KU Leuven, Heverlee; Department of Neurology (W.V.), University Hospitals Leuven; Department of Neurosciences (W.V.), KU Leuven, Leuven; CARA Department (M.T.), Belgian Road Safety Institute, Brussels, Belgium; Department of Neurology (E.Y.U.), University of Iowa, Iowa City; and Neurology Service (E.Y.U.), Veterans Affairs Medical Center, Iowa City, IA.

Objective: To determine the driving skill impairments and underlying visual, motor, and cognitive deficits that lead to failure on road testing in manifest Huntington disease (HD).

Methods: Certified driving assessment experts scored performance on 13 specific on-road driving skills in 30 persons with HD and 30 controls and issued a pass/fail decision based on their overall impression. These on-road skill items were mapped onto an existing theoretical framework that categorized driving skills into operational, tactical, visuo-integrative, and mixed clusters. The HD group additionally completed a detailed off-road battery of motor, visual, and neuropsychological tests.

Results: The HD group performed worse on all on-road items. Fourteen drivers with HD (47%) failed the road test compared with none of the controls. Scores on the Total Functional Capacity scale discriminated significantly between pass and fail groups. Total on-road score and performance in operational, tactical, and visuo-integrative clusters correlated strongly (Spearman ρ >0.50) with the pass/fail decision. The off-road tests showed variable strengths of association depending on the level of driving skill. Selective attention was strongly associated (Spearman ρ >0.50) with the total on-road score and all driving clusters.

Conclusions: HD affects driving at many levels due to motor and cognitive deficits and leads to unsafe road performance even in mild stages. The high failure rate on the road test and difficulties in all aspects of on-road driving suggest that monitoring of fitness to drive should be initiated in the early course of HD.
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http://dx.doi.org/10.1212/WNL.0000000000000220DOI Listing
March 2014

Driving and off-road impairments underlying failure on road testing in Parkinson's disease.

Mov Disord 2013 Dec 24;28(14):1949-56. Epub 2013 Oct 24.

Department of Rehabilitation Sciences, Katholieke Universiteit (KU) Leuven-University of Leuven, Leuven, Belgium; National Advanced Driving Simulator, University of Iowa, Iowa City, Iowa, USA; Department of Physical Therapy, Georgia Regents University, Augusta, Georgia, USA.

Parkinson's disease (PD) affects driving ability. We aimed to determine the most critical impairments in specific road skills and in clinical characteristics leading to failure on a road test in PD. In this cross-sectional study, certified driving assessment experts evaluated specific driving skills in 104 active, licensed drivers with PD using a standardized, on-road checklist and issued a global decision of pass/fail. Participants also completed an off-road evaluation assessing demographic features, disease characteristics, motor function, vision, and cognition. The most important driving skills and off-road predictors of the pass/fail outcome were identified using multivariate stepwise regression analyses. Eighty-six (65%) passed and 36 (35%) failed the on-road driving evaluation. Persons who failed performed worse on all on-road items. When adjusted for age and gender, poor performances on lateral positioning at low speed, speed adaptations at high speed, and left turning maneuvers yielded the best model that determined the pass/fail decision (R(2) = 0.56). The fail group performed poorer on all motor, visual, and cognitive tests. Measures of visual scanning, motor severity, PD subtype, visual acuity, executive functions, and divided attention were independent predictors of pass/fail decisions in the multivariate model (R(2) = 0.60). Our study demonstrated that failure on a road test in PD is determined by impairments in specific driving skills and associated with deficits in motor, visual, executive, and visuospatial functions. These findings point to specific driving and off-road impairments that can be targeted in multimodal rehabilitation programs for drivers with PD.
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http://dx.doi.org/10.1002/mds.25701DOI Listing
December 2013

Impact of specific executive functions on driving performance in people with Parkinson's disease.

Mov Disord 2013 Dec 1;28(14):1941-8. Epub 2013 Oct 1.

IFSTTAR, LEPSIS, Marne La Vallée, France.

Executive functions encompass various cognitive processes and are critical in novel or demanding driving situations. Our aim was to determine the role of impairments in specific executive functions (updating, flexibility, inhibition) on road performance in drivers with Parkinson's disease (PD), a condition commonly associated with early executive dysfunction. In this pilot study, 19 patients with mild to moderate PD and 21 healthy controls matched for age, education, and driving experience were tested using a neuropsychological battery assessing global cognitive abilities, updating (n-back task), flexibility (plus-minus task), and inhibition (Stroop test). Participants also underwent a 45-minute road test in which they were scored by a driving instructor and a second experimenter. To separate "at-risk" drivers from safe drivers, a composite driving indicator was calculated from the Test Ride for Investigating Practical Fitness to Drive score, the penalty score from the observation grid, and the number of safety interventions made by the driving instructor. Eight of the 40 drivers (all PD) were rated as "at risk." Measures of updating (the n-back task) and mental flexibility (the plus-minus task) predicted driving safety even after adjustment for group status, explaining 53% of the total variance. These 2 tests also discriminated between safe and "at-risk" drivers within the PD group. These findings, although preliminary, suggest that updating and mental flexibility are critical for safe driving in PD. Assessment batteries for driving fitness should probe different aspects of executive functions, specifically when evaluating drivers with PD.
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http://dx.doi.org/10.1002/mds.25660DOI Listing
December 2013

Randomized trial of cognitive speed of processing training in Parkinson disease.

Neurology 2013 Oct 6;81(15):1284-90. Epub 2013 Sep 6.

From the School of Aging Studies (J.D.E., E.G.V.) and Department of Neurology (R.A.H., T.A.Z.), University of South Florida, Tampa; Department of Human Development and Family Science (M.L.O.), North Dakota State University, Fargo; Department of Neurology (E.Y.U.), University of Iowa, Iowa City; and Neurology Service (E.Y.U.), Veterans Affairs Medical Center, Iowa City.

Objective: To examine the efficacy of cognitive speed of processing training (SOPT) among individuals with Parkinson disease (PD). Moderators of SOPT were also examined.

Methods: Eighty-seven adults, 40 years of age or older, with a diagnosis of idiopathic PD in Hoehn & Yahr stages 1-3 and on a stable medication regimen were randomized to either 20 hours of self-administered SOPT (using InSight software) or a no-contact control condition. Participants were assessed at baseline and after 3 months of training (or an equivalent delay). The primary outcome measure was useful field of view test (UFOV) performance, and secondary outcomes included cognitive self-perceptions and depressive symptoms.

Results: Results indicated that participants randomized to SOPT experienced significantly greater improvements on UFOV performance relative to controls, Wilks λ = 0.938, F 1,72 = 4.79, p = 0.032, partial η(2) = 0.062. Findings indicated no significant effect of training on secondary outcomes, Wilks λ = 0.987, F2,70 < 1, p = 0.637, partial η(2) = 0.013.

Conclusions: Patients with mild to moderate stage PD can self-administer SOPT and improve their cognitive speed of processing, as indexed by UFOV (a robust predictor of driving performance in aging and PD). Further research should establish if persons with PD experience longitudinal benefits of such training and if improvements translate to benefits in functional activities such as driving.

Classification Of Evidence: This study provides Class III evidence that SOPT improves UFOV performance among persons in the mild to moderate stages of PD.
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http://dx.doi.org/10.1212/WNL.0b013e3182a823baDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806923PMC
October 2013

Naturalistic distraction and driving safety in older drivers.

Hum Factors 2013 Aug;55(4):841-53

University of Iowa, Iowa City, IA 52242, USA.

Objective: In this study, we aimed to quantify and compare performance of middle-aged and older drivers during a naturalistic distraction paradigm (visual search for roadside targets) and to predict older drivers performance given functioning in visual, motor, and cognitive domains.

Background: Distracted driving can imperil healthy adults and may disproportionally affect the safety of older drivers with visual, motor, and cognitive decline.

Method: A total of 203 drivers, 120 healthy older (61 men and 59 women, ages 65 years and older) and 83 middle-aged drivers (38 men and 45 women, ages 40 to 64 years), participated in an on-road test in an instrumented vehicle. Outcome measures included performance in roadside target identification (traffic signs and restaurants) and concurrent driver safety. Differences in visual, motor, and cognitive functioning served as predictors.

Results: Older drivers identified fewer landmarks and drove slower but committed more safety errors than did middle-aged drivers. Greater familiarity with local roads benefited performance of middle-aged but not older drivers.Visual cognition predicted both traffic sign identification and safety errors, and executive function predicted traffic sign identification over and above vision.

Conclusion: Older adults are susceptible to driving safety errors while distracted by common secondary visual search tasks that are inherent to driving. The findings underscore that age-related cognitive decline affects older drivers' management of driving tasks at multiple levels and can help inform the design of on-road tests and interventions for older drivers.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880225PMC
http://dx.doi.org/10.1177/0018720812465769DOI Listing
August 2013

Prefrontal dopamine signaling and cognitive symptoms of Parkinson's disease.

Rev Neurosci 2013 ;24(3):267-78

Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, IA, USA.

Cognitive dysfunction is a common symptom of Parkinson's disease (PD) that causes significant morbidity and mortality. The severity of these symptoms ranges from minor executive symptoms to frank dementia involving multiple domains. In the present review, we will concentrate on the aspects of cognitive impairment associated with prefrontal dopaminergic dysfunction, seen in non-demented patients with PD. These symptoms include executive dysfunction and disorders of thought, such as hallucinations and psychosis. Such symptoms may go on to predict dementia related to PD, which involves amnestic dysfunction and is typically seen later in the disease. Cognitive symptoms are associated with dysfunction in cholinergic circuits, in addition to the abnormalities in the prefrontal dopaminergic system. These circuits can be carefully studied and evaluated in PD, and could be leveraged to treat difficult clinical problems related to cognitive symptoms of PD.
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http://dx.doi.org/10.1515/revneuro-2013-0004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836593PMC
November 2013

Validation of a screening battery to predict driving fitness in people with Parkinson's disease.

Mov Disord 2013 May 23;28(5):671-4. Epub 2013 Feb 23.

Department of Rehabilitation Sciences, KU Leuven, Heverlee, Belgium.

Background: We previously developed a short clinical battery, consisting of contrast sensitivity, Clinical Dementia Rating, the Unified Parkinson's Disease Rating Scale-motor section (UPDRS III), and disease duration, which correctly classified 90% of drivers with Parkinson's Disease (PD). The aim of this study was to validate that screening battery in a different sample of PD drivers.

Methods: Sixty drivers with PD were enrolled to validate our original screening battery to predict driving fitness decisions (pass-fail) by a state agency where drivers underwent detailed visual, cognitive, and on-road testing.

Results: Twenty-four participants (40%) failed the driving evaluation. The screening battery correctly classified 46 (77%) participants (sensitivity and negative predictive value = 96%; specificity and positive predictive value = 64%). Adding other clinical predictors (e.g., age of onset, Hoehn-Yahr stage instead of UPDRS III) failed to improve the specificity of the model when the sensitivity was kept constant at 96%. However, a driving simulator evaluation improved the specificity of the model to 94%.

Conclusions: The original clinical battery proved to be a valid screening tool that accurately identifies fit drivers with PD and select those who need more detailed testing at specialized centers.
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http://dx.doi.org/10.1002/mds.25387DOI Listing
May 2013

Parkinson disease and driving: an evidence-based review.

Neurology 2012 Nov;79(20):2067-74

Departments of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA.

The growing literature on driving in Parkinson disease (PD) has shown that driving is impaired in PD compared to healthy comparison drivers. PD is a complex neurodegenerative disorder leading to motor, cognitive, and visual impairments, all of which can affect fitness to drive. In this review, we examined studies of driving performance (on-road tests and simulators) in PD for outcome measures and their predictors. We searched through various databases and found 25 (of 99) primary studies, all published in English. Using the American Academy of Neurology criteria, a study class of evidence was assigned (I-IV, I indicating the highest level of evidence) and recommendations were made (Level A: predictive or not; B: probably predictive or not; C: possibly predictive or not; U: no recommendations). From available Class II and III studies, we identified various cognitive, visual, and motor measures that met different levels of evidence (usually Level B or C) with respect to predicting on-road and simulated driving performance. Class I studies reporting Level A recommendations for definitive predictors of driving performance in drivers with PD are needed by policy makers and clinicians to develop evidence-based guidelines.
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http://dx.doi.org/10.1212/WNL.0b013e3182749e95DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3511919PMC
November 2012

Neuropsychological assessment of driving safety risk in older adults with and without neurologic disease.

J Clin Exp Neuropsychol 2012 3;34(9):895-905. Epub 2012 Sep 3.

Division of Neuroergonomics, Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.

Decline in cognitive abilities can be an important contributor to the driving problems encountered by older adults, and neuropsychological assessment may provide a practical approach to evaluating this aspect of driving safety risk. The purpose of the present study was to evaluate several commonly used neuropsychological tests in the assessment of driving safety risk in older adults with and without neurological disease. A further goal of this study was to identify brief combinations of neuropsychological tests that sample performances in key functional domains and thus could be used to efficiently assess driving safety risk. A total of 345 legally licensed and active drivers over the age of 50, with no neurologic disease (N = 185), probable Alzheimer's disease (N = 40), Parkinson's disease (N = 91), or stroke (N = 29), completed vision testing, a battery of 10 neuropsychological tests, and an 18-mile drive on urban and rural roads in an instrumented vehicle. Performances on all neuropsychological tests were significantly correlated with driving safety errors. Confirmatory factor analysis was used to identify 3 key cognitive domains assessed by the tests (speed of processing, visuospatial abilities, and memory), and several brief batteries consisting of one test from each domain showed moderate corrected correlations with driving performance. These findings are consistent with the notion that driving places demands on multiple cognitive abilities that can be affected by aging and age-related neurological disease, and that neuropsychological assessment may provide a practical off-road window into the functional status of these cognitive systems.
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http://dx.doi.org/10.1080/13803395.2011.630654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3910382PMC
April 2013

Clinical predictors of driving status in Huntington's disease.

Mov Disord 2012 Aug 28;27(9):1146-52. Epub 2012 Jun 28.

Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.

The aim of this study was to identify the motor, cognitive, and behavioral determinants of driving status and risk factors for driving cessation in Huntington's disease (HD). Seventy-four patients with HD were evaluated for cognitive, motor, psychiatric, and functional status using a standardized battery (Unified Huntington's Disease Rating Scale [UHDRS] and supplemental neuropsychological testing) during a research clinic visit. Chart review was used to categorize patients into two driving status categories: (1) "currently driving" included those driving and driving but with clinician recommendation to restrict, and (2) "not driving" included those with clinician recommendation to cease driving and those not currently driving because of HD. Multi- and univariate logistic regression was used to identify significant clinical predictors of those driving versus not driving. Global cognitive performance and UHDRS Total Functional Capacity scores provided the best predictive model of driving cessation (Nagelkerke R(2) = 0.65; P < 0.0001). Measures of learning (P = 0.006) and psychomotor speed/attention (P = 0.003) accounted for the overall cognitive finding. In univariate analyses, numerous cognitive, motor, and daily functioning items were significantly associated with driving. Although driving status is associated with many aspects of the disease, results suggest that the strongest association is with cognitive performance. A detailed cognitive evaluation is an important component of multidisciplinary clinical assessment in patients with HD who are driving.
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http://dx.doi.org/10.1002/mds.25101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638899PMC
August 2012

Predictors of driving outcomes in advancing age.

Psychol Aging 2012 Sep 19;27(3):550-9. Epub 2011 Dec 19.

Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.

This study aimed to develop predictive models for real-life driving outcomes in older drivers. Demographics, driving history, on-road driving errors, and performance on visual, motor, and neuropsychological test scores at baseline were assessed in 100 older drivers (ages 65-89 years [72.7]). These variables were used to predict time to driving cessation, first moving violation, or crash. Using Cox proportional hazards regression models, significant individual predictors for driving cessation were greater age and poorer scores on Near Visual Acuity, Contrast Sensitivity, Useful Field of View, Judgment of Line Orientation, Trail Making Test-Part A, Benton Visual Retention Test, Grooved Pegboard, and a composite index of overall cognitive ability. Greater weekly mileage, higher education, and "serious" on-road errors predicted moving violations. Poorer scores from Trail Making Test-Part B or Trail Making Test (B-A) and serious on-road errors predicted crashes. Multivariate models using "off-road" predictors revealed (a) age and Contrast Sensitivity as best predictors for driving cessation; (b) education, weekly mileage, and Auditory Verbal Learning Task-Recall for moving violations; and (c) education, number of crashes over the past year, Auditory Verbal Learning Task-Recall, and Trail Making Test (B-A) for crashes. Diminished visual, motor, and cognitive abilities in older drivers can be easily and noninvasively monitored with standardized off-road tests, and performances on these measures predict involvement in motor vehicle crashes and driving cessation, even in the absence of a neurological disorder.
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http://dx.doi.org/10.1037/a0026359DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3360997PMC
September 2012

Body mass index in Parkinson's disease: a meta-analysis.

Parkinsonism Relat Disord 2012 Mar 18;18(3):263-7. Epub 2011 Nov 18.

Radboud University Nijmegen Medical Centre, Nijmegen Centre for Evidence Based Practice, Department of Neurology, Nijmegen, The Netherlands.

Prior work suggested that patients with Parkinson's disease (PD) have a lower Body Mass Index (BMI) than controls, but evidence is inconclusive. We therefore conducted a meta-analysis on BMI in PD. We searched MEDLINE, EMBASE, Cinahl and Scopus to identify cohort studies on BMI in PD, published before February 2011. Studies that reported mean BMI for PD patients and healthy controls were eligible. Twelve studies were included, with a total of 871 patients and 736 controls (in three studies controls consisted of subjects from other published studies). Our primary aim was to assess differences in BMI between patients and controls; this was analyzed with random effects meta-analysis. Our secondary aim was to evaluate the relation with disease severity (Hoehn and Yahr stage) and disease duration, using random effects meta-regression. PD patients had a significantly lower BMI than controls (overall effect 1.73, 95% CI 1.11-2.35, P<0.001). Pooled data of seven studies showed that patients with Hoehn and Yahr stage 3 had a lower BMI than patients with stage 2 (3.9, 95% CI 0.1-7.7, P<0.05). Disease duration was not associated with BMI. Because a low body weight is associated with negative health effects and a poorer prognosis, monitoring weight and nutritional status should be part of PD management.
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http://dx.doi.org/10.1016/j.parkreldis.2011.10.016DOI Listing
March 2012

Cognitive functioning predicts driver safety on road tests 1 and 2 years later.

J Am Geriatr Soc 2012 Jan 31;60(1):99-105. Epub 2011 Oct 31.

Division of Neuroergonomics, Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.

Objectives: To describe longitudinal changes in mean level and evaluate rank-order stability in potential predictors of driving safety (visual sensory, motor, visual attention, and cognitive functioning) and safety errors during an 18-mile on-road driving test in older adults and to evaluate the relative predictive power of earlier visual sensory, motor, visual attention, and cognitive functioning on future safety errors, controlling for earlier driving capacity.

Design: Three-year longitudinal observational study.

Setting: Large teaching hospital in the Midwest.

Participants: One hundred eleven neurologically normal older adults (60-89 at baseline).

Measurements: Safety errors based on video review of a standard 18-mile on-road driving test served as the outcome measure. A comprehensive battery of tests on the predictor side included visual sensory functioning, motor functioning, cognitive functioning, and a measure of useful field of view.

Results: Longitudinal changes in mean levels of safety errors and cognitive functioning were small from year to year. Relative rank-order stability between consecutive assessments was moderate in overall safety errors and moderate to strong in visual attention and cognitive functioning. Although prospective bivariate correlations between safety errors and predictors ranged from fair to moderate, only functioning in the cognitive domain predicted future driver performance 1 and 2 years later in multivariate analyses.

Conclusion: Normative aging-related declines in driver performance as assessed using on-road tests emerge slowly. Even in the presence of conservative controls, such as previous driving ability, age, and visual sensory and motor functioning, cognitive functioning predicted future on-road driving performance 1 and 2 years later.
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http://dx.doi.org/10.1111/j.1532-5415.2011.03739.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258369PMC
January 2012

A recommended scale for cognitive screening in clinical trials of Parkinson's disease.

Mov Disord 2010 Nov;25(15):2501-7

Department of Neurology, University of Michigan, Ann Arbor, Michigan 48109-5316, USA.

Cognitive impairment is common in Parkinson's disease (PD). There is a critical need for a brief, standard cognitive screening measure for use in PD trials whose primary focus is not on cognition. The Parkinson Study Group (PSG) Cognitive/Psychiatric Working Group formed a Task Force to make recommendations for a cognitive scale that could screen for dementia and mild cognitive impairment in clinical trials of PD where cognition is not the primary outcome. This Task Force conducted a systematic literature search for cognitive assessments previously used in a PD population. Scales were then evaluated for their appropriateness to screen for cognitive deficits in clinical trials, including brief administration time (<15 minutes), assessment of the major cognitive domains, and potential to detect subtle cognitive impairment in PD. Five scales of global cognition met the predetermined screening criteria and were considered for review. Based on the Task Force's evaluation criteria the Montreal Cognitive Assessment (MoCA), appeared to be the most suitable measure. This Task Force recommends consideration of the MoCA as a minimum cognitive screening measure in clinical trials of PD where cognitive performance is not the primary outcome measure. The MoCA still requires further study of its diagnostic utility in PD populations but appears to be the most appropriate measure among the currently available brief cognitive assessments. Widespread adoption of a single instrument such as the MoCA in clinical trials can improve comparability between research studies on PD.
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http://dx.doi.org/10.1002/mds.23362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2978783PMC
November 2010

Neuropsychological predictors of driving errors in older adults.

J Am Geriatr Soc 2010 Jun 7;58(6):1090-6. Epub 2010 May 7.

Department of Biostatistics, University of Iowa, Iowa City, Iowa 52242, USA.

Objectives: To identify neuropsychological factors associated with driving errors in older adults.

Design: Cross-sectional observational study.

Setting: Neuropsychological assessment laboratory and an instrumented vehicle on a 35-mile route on urban and rural roads.

Participants: One hundred eleven older adult drivers (aged 65-89; mean age 72.3) and 80 middle-aged drivers (aged 40-64; mean age 57.2).

Measurements: Explanatory variables included age, neuropsychological measures (cognitive, visual, and motor), and a composite cognitive score (COGSTAT). The outcome variable was the safety error count, as classified according to video review using a standardized taxonomy.

Results: Older drivers committed an average of 35.8 +/- 12.8 safety errors per drive, compared with an average of 27.8 +/- 9.8 for middle-aged drivers (P<.001). For older drivers, there was an increase of 2.6 errors per drive observed for each 5-year age increase (P=.03). After adjustment for age, education, and sex, COGSTAT was a significant predictor of safety errors in older drivers (P=.005), with an approximately 10% increase in safety errors observed for a 10% decrease in cognitive function. Individual significant predictors of more safety errors in older drivers included poorer scores on the Complex Figure Test--Copy, the Complex Figure Test--Recall, Block Design, Near Visual Acuity, and the Grooved Pegboard task.

Conclusion: Driving errors in older adults tend to increase, even in the absence of neurological diagnoses. Age-related decline in cognitive abilities, vision, and motor skills can explain some of this increase. Changes in visuospatial and visuomotor abilities appear to be particularly associated with unsafe driving in old age.
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http://dx.doi.org/10.1111/j.1532-5415.2010.02872.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204878PMC
June 2010

Prediction of driving ability with neuropsychological tests: demographic adjustments diminish accuracy.

J Int Neuropsychol Soc 2010 Jul 5;16(4):679-86. Epub 2010 May 5.

Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.

Demographically adjusted norms generally enhance accuracy of inferences based on neuropsychological assessment. However, we hypothesized that demographic corrections diminish predictive accuracy for real-world activities with absolute cognitive demands. Driving ability was assessed with a 45-minute drive along a standardized on-road route in participants aged 65+ (24 healthy elderly, 26 probable Alzheimer's disease, 33 Parkinson's disease). Neuropsychological measures included: Trail-Making A and B, Complex Figure, Benton Visual Retention, and Block Design tests. A multiple regression model with raw neuropsychological scores was significantly predictive of driving errors (R2 = .199, p = .005); a model with demographically adjusted scores was not (R2 = .113, p = .107). Raw scores were more highly correlated with driving errors than were adjusted scores for each neuropsychological measure, and among healthy elderly and Parkinson's patients. When predicting real-world activities that depend on absolute levels of cognitive abilities regardless of demographic considerations, predictive accuracy is diminished by demographic corrections.
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http://dx.doi.org/10.1017/S1355617710000470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3152745PMC
July 2010

Detection of imminent collisions by drivers with Alzheimer's disease and Parkinson's disease: a preliminary study.

Accid Anal Prev 2010 May;42(3):852-8

Dept. of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.

The aim of this study was to assess whether patients with neurodegenerative disease, namely Alzheimer's disease (AD) and Parkinson's disease (PD), differed from age-matched, neurologically normal comparison participants in their ability to detect impending collisions. Six AD patients and 8 PD patients, together comprising the neurodegenerative disease group, and 18 comparison participants completed a collision detection simulation task where they must judge whether approaching objects would collide with them or pass by them. The neurodegenerative disease group was less sensitive in detecting collisions than the comparison group, and sensitivity worsened with increasing number of objects in the display and increasing time to contact of those objects. Poor performance on tests of cognition and visual attention were associated with poor collision detection sensitivity. The results of this study indicate that neurodegenerative disease impairs the ability to accurately detect impending collisions and that these decrements are likely the combined result of visual and cognitive disturbances related to disease status.
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http://dx.doi.org/10.1016/j.aap.2009.07.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3102017PMC
May 2010
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