Associations between changes in somatic and psychiatric symptoms and disability alterations in recent-era U.S. veterans.

Cross-sectional work suggests that deployment-related posttraumatic sequelae are associated with increased disability in U.S. veterans deployed following the September 11, 2001 (9/11), terrorist attacks. However, few studies have examined the psychiatric and somatic variables associated with changes in functional disability over time. A total of 237 post-9/11 veterans completed comprehensive assessments of psychiatric and cognitive functioning, as well as a disability questionnaire, at baseline and 2-year follow-up. At baseline, higher levels of PTSD, depressive, and pain-related symptoms were associated with baseline global functional disability, semipartial r2 = .036-.044. Changes in symptoms of PTSD, depression, pain, and sleep, but not anxiety or alcohol use, were independently associated with changes in functional disability, semipartial r2 = .017-.068. Baseline symptoms of these conditions were unrelated to changes in disability, and cognitive performance was unrelated to disability at any assessment point. Together, this suggests that changes in psychiatric and somatic symptoms are tightly linked with changes in functional disability and should be frequently monitored, and even subclinical symptoms may be a target of intervention.

Connectome-based functional connectivity markers of suicide attempt.

BACKGROUND: Functional brain markers of suicidality can help identify at-risk individuals and uncover underlying neurocognitive mechanism(s). Although some converging evidence has implicated dysfunction in several brain networks, suicide-related neuroimaging markers are inconsistent across studies, due to heterogeneity of neuroimaging approaches, clinical populations, and experimental methods. METHODS: The current study aimed to address these limitations by examining resting-fMRI connectivity in a sample of post-9/11 veterans with a past suicide attempt (SA; n = 16) compared to a psychiatric control group (PC; n = 124) with no SA history but comparable past and present symptomatology, as well as a trauma control group (TC; n = 66) of trauma-exposed healthy controls. We used both a novel graph-analytic and seed-based approach to characterize SA-related connectivity differences across brain networks. RESULTS: First, the graph-analytic approach identified the right amygdala and a region in the cognitive control network (right middle temporal gyrus; MTG) as regional SA-related hubs of dysfunction (HoD), or regions that exhibited a high number of SA-related connections. Aberrant SA-related connectivity between these hubs spanned multiple networks, including the cognitive control, default mode and visual networks. Second, the seed-based connectivity analysis that identifies SA-related differences in the strength of neural connections across the whole brain further implicated the right amygdala. LIMITATIONS: Small sample size and potential underreporting of SA. CONCLUSIONS: These two analytic approaches preliminarily suggest that the right amygdala and right MTG may be specific neural markers of SA that can be differentiated from neural markers of psychopathology more broadly.

The Impact of Common Psychiatric and Behavioral Comorbidities on Functional Disability Across Time and Individuals in Post-9/11 Veterans.

Returning veterans often face multiple concurrent psychiatric and behavioral conditions that negatively impact reintegration into civilian life and are associated with functional disability. Understanding how conditions interact to negatively impact functioning is an important step toward developing holistic treatment approaches optimized for this population. This study utilized a cross-sectional and prospective longitudinal cohort design, applying regression algorithms to understand the relative contribution of common clinical issues to functional disability in U.S. veterans who served after the September 11, 2001 (9/11), terror attacks. Community-dwelling post-9/11 veterans (N = 397) completed detailed assessments, including common clinical condition diagnoses, combat experience, and demographics, which were used to predict functional disability (World Health Organization Disability Assessment Schedule); 205 participants were reassessed approximately 1-2 years after enrollment. Regression analyses showed a strong association between the predictor variables and functional disability, f 2 = 1.488. Validation analyses showed a high prediction ability of functional disability to independent samples, r = .719, and across time in the same individuals, r = .780. The strongest predictors included current posttraumatic stress disorder, depressive disorder, sleep disturbance, and pain diagnoses. These results demonstrate the importance of considering multiple common co-occurring conditions when assessing functional disability in post-9/11 veterans and suggest that certain syndromes contribute the most unique information to predicting functional disability with high confidence. As most U.S. veterans utilize private healthcare systems, these results have clinical utility for both Veterans Affairs and civilian healthcare practitioners in assessing and monitoring functional disability in post-9/11 veterans over time.

The Deployment Trauma Phenotype and Employment Status in Veterans of the Wars in Iraq and Afghanistan.

OBJECTIVES: To determine the prevalence of comorbid mild traumatic brain injury (mTBI), posttraumatic stress disorder (PTSD), and depression, termed the deployment trauma phenotype (DTP), and its constituent diagnoses' impact on unemployment status in a national cohort of veterans. SETTING: Retrospective analysis of the comprehensive TBI evaluation, a Veterans Affairs-wide protocol for assessing TBI, employment status, and psychiatric impressions. PARTICIPANTS: The final data set consisted of 48 821 veterans. MAIN OUTCOMES AND MEASURES: Frequency of mTBI, PTSD, and depression in isolation and combinations and their association with unemployment status. RESULTS: Age- and education-adjusted risk ratios (RRs) showed that the mTBI-only group was the least likely to be unemployed, RR = 0.65 (0.59-0.71). By contrast, the greatest likelihood of unemployment was associated with membership in the DTP group, RR = 1.45 (1.36-1.56), and the comorbid PTSD and depression group, RR = 1.39 (1.27-1.52). Furthermore, the DTP was nearly 3 times more prevalent (16.4%) in this sample compared with comorbid PTSD and depression (5.7%), indicating that the DTP conveys risk for unemployment to a significantly greater number of individuals. CONCLUSIONS AND RELEVANCE: The comorbid and interactive conditions of PTSD, depression, and mTBI, rather than mTBI in isolation, were linked to significant risk for unemployment in this veteran cohort. These findings suggest that multifaceted assessments and interventions to improve postdeployment reintegration are needed.

Associations Among Posttraumatic Stress Disorder Symptoms, Substance Use, and Affective Attentional Processing in OEF/OIF/OND Veterans.

The majority of research examining affective attentional bias in posttraumatic stress disorder (PTSD) has not examined the influence of co-occurring psychiatric disorders. This study examined the individual and interactive effects of PTSD symptoms and substance use disorders (SUDs) on affective attentional processing among 323 veterans deployed to Iraq or Afghanistan. Participants were divided into those with SUD (SUD+, n = 46) and those without (SUD-, n = 277). Substance use disorder was determined using the Structured Clinical Interview for DSM-IV. Posttraumatic stress disorder was measured using the Clinician Administered PTSD Scale. A computerized go/no-go task (Robbins et al., 1994, Robbins et al.,1998) assessed affective attentional processing. Relative to those without SUD, those with SUD showed a significant association between PTSD symptoms and increased omission and commission accuracy rates and decreased d prime. No effects of valence were found. Findings suggest the need to consider co-occurring SUD when investigating the effects of PTSD on attentional control.

Early life trauma is associated with altered white matter integrity and affective control.

Early life trauma (ELT) has been shown to impair affective control and attention well into adulthood. Neuroimaging studies have further shown that ELT was associated with decreased white matter integrity in the prefrontal areas in children and adults. However, no study to date has looked at the relationship between white matter integrity and affective control in individuals with and without a history of ELT. To examine this, we tested 240 Veterans with (ELT N = 80) and without (NoELT N = 160) a history of childhood sexual abuse, physical abuse or family violence. Affective control was measured with the Affective Go/No-Go (AGN) and attention was indexed with the Test of Variable Attention (TOVA). White matter integrity was measured using fractional anisotropy (FA). Results showed greater number of errors on the AGN in ELT compared to NoELT. There was no difference on the TOVA. While there were no mean differences in FA, there was an interaction between FA and reaction time to positive stimuli on the AGN where the ELT group showed a positive relationship between FA and reaction time in right frontal and prefrontal areas, whereas the NoELT group showed a negative or no association between FA and reaction time. This suggests that ELT may be associated with a distinct brain-behavior relationship that could be related to other determinants of FA than those present in healthy adults.

Feasibility of use of probabilistic reversal learning and serial reaction time tasks in clinical trials of Parkinson's disease.

INTRODUCTION: The aim of this study was to investigate the feasibility of using two computer-administered neuropsychological tasks in a clinical trial involving participants with Parkinson's disease without dementia. The tasks, probabilistic reversal learning (PRL) and serial reaction time (SRT), target dorsolateral prefrontal cortex (SRT) and ventral striatal-orbitofrontal (PRL) functioning respectively. METHODS: Participants were 53 adults with idiopathic Parkinson's disease who completed both the SRT and PRL tasks at baseline in a clinical trial. Repeated measures were examined only for the placebo group (n = 20). RESULTS: No participants were removed from analyses due to inability to complete the tasks, and most had fewer than 10% of trials culled due to slow reaction times. Response accuracy on PRL was 81.98% and 66.65% for the two stages of the task respectively. Disease duration was associated with SRT relearning. Disease duration and stage were associated with initial learning on PRL, and there was a trend towards disease stage predicting greater errors on PRL. Among participants in the placebo group, practice effects were seen on PRL (Phase 1 errors) and SRT (relearning). CONCLUSIONS: These results provide initial evidence for the clinical feasibility of computerized PRL and SRT tasks in clinical trials in Parkinson's disease.

Neurobiological indicators of disinhibition in posttraumatic stress disorder.

Deficits in impulse control are increasingly recognized in association with posttraumatic stress disorder (PTSD). To our further understanding of the neurobiology of PTSD-related disinhibition, we examined alterations in brain morphology and network connectivity associated with response inhibition failures and PTSD severity. The sample consisted of 189 trauma-exposed Operation Enduring Freedom/Operation Iraqi Freedom veterans (89% male, ages 19-62) presenting with a range of current PTSD severity. Disinhibition was measured using commission errors on a Go/No-Go (GNG) task with emotional stimuli, and PTSD was assessed using a measure of current symptom severity. Whole-brain vertex-wise analyses of cortical thickness revealed two clusters associated with PTSD-related disinhibition (Monte Carlo cluster corrected P < 0.05). The first cluster included portions of right inferior and middle frontal gyri and frontal pole. The second cluster spanned portions of left medial orbital frontal, rostral anterior cingulate, and superior frontal gyrus. In both clusters, commission errors were associated with reduced cortical thickness at higher (but not lower) levels of PTSD symptoms. Resting-state functional magnetic resonance imaging analyses revealed alterations in the functional connectivity of the right frontal cluster. Together, study findings suggest that reductions in cortical thickness in regions involved in flexible decision-making, emotion regulation, and response inhibition contribute to impulse control deficits in PTSD. Furthermore, aberrant coupling between frontal regions and networks involved in selective attention, memory/learning, and response preparation suggest disruptions in functional connectivity may also play a role.

Deployment-related psychiatric and behavioral conditions and their association with functional disability in OEF/OIF/OND veterans.

Understanding the factors that influence veterans' functional outcome after deployment is critical to provide appropriately targeted care. Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) have been related to disability, but other psychiatric and behavioral conditions are not as well examined. We investigated the impact of deployment-related psychiatric and behavioral conditions on disability among 255 OEF/OIF/OND service members and veterans. Structured clinical interviews assessed TBI and the psychiatric conditions of depression, PTSD, anxiety, and substance use. Self-report questionnaires assessed disability and the behavioral conditions of sleep disturbance and pain. Over 90% of participants had a psychiatric and/or behavioral condition, with approximately half presenting with ≥ 3 conditions. Exploratory factor analysis revealed 4 clinically relevant psychiatric and behavioral factors which accounted for 76.9% of the variance: (a) depression, PTSD, and military mTBI (deployment trauma factor); (b) pain and sleep (somatic factor); (c) anxiety disorders, other than PTSD (anxiety factor); and (d) substance abuse or dependence (substance use factor). Individuals with the conditions comprising the deployment trauma factor were more likely to be substantially disabled than individuals with depression and PTSD, but no military mTBI, OR = 3.52; 95% CI [1.09, 11.37]. Depression, PTSD, and a history of military mTBI may comprise an especially harmful combination associated with high risk for substantial disability.

Correspondence of the Boston Assessment of Traumatic Brain Injury-Lifetime (BAT-L) clinical interview and the VA TBI screen.

OBJECTIVE: Mild traumatic brain injury is the signature injury of Operation Enduring Freedom (OEF), Operation Iraqi Freedom (OIF), and Operation New Dawn (OND), yet its identification and diagnosis is controversial and fraught with challenges. SETTING: In 2007, the Department of Veterans Affairs (VA) implemented a policy requiring traumatic brain injury (TBI) screening on all individuals returning from deployment in the OEF/OIF/OND theaters of operation that lead to the rapid and widespread use of the VA TBI screen. The Boston Assessment of TBI-Lifetime (BAT-L) is the first validated, postcombat semistructured clinical interview to characterize head injuries and diagnose TBIs throughout the life span, including prior to, during, and post-military service. PARTICIPANTS: Community-dwelling convenience sample of 179 OEF/OIF/OND veterans. MAIN MEASURES: BAT-L, VA TBI screen. RESULTS: Based on BAT-L diagnosis of military TBI, the VA TBI screen demonstrated similar sensitivity (0.85) and specificity (0.82) when administered by research staff. When BAT-L diagnosis was compared with historical clinician-administered VA TBI screen in a subset of participants, sensitivity was reduced. CONCLUSIONS: The specificity of the research-administered VA TBI screen was more than adequate. The sensitivity of the VA TBI screen, although relatively high, suggests that it does not oversample or "catch all" possible military TBIs. Traumatic brain injuries identified by the BAT-L, but not identified by the VA TBI screen, were predominantly noncombat military injuries. There is potential concern regarding the validity and reliability of the clinician administered VA TBI screen, as we found poor correspondence between it and the BAT-L, as well as low interrater reliability between the clinician-administered and research-administered screen.

Reduced cortical thickness in veterans exposed to early life trauma.

Studies have shown that early life trauma may influence neural development and increase the risk of developing psychological disorders in adulthood. We used magnetic resonance imaging to examine the impact of early life trauma on the relationship between current posttraumatic stress disorder (PTSD) symptoms and cortical thickness/subcortical volumes in a sample of deployed personnel from Operation Enduring Freedom/Operation Iraqi Freedom. A group of 108 service members enrolled in the Translational Research Center for Traumatic Brain Injury and Stress Disorders (TRACTS) were divided into those with interpersonal early life trauma (EL-Trauma+) and Control (without interpersonal early life trauma) groups based on the Traumatic Life Events Questionnaire. PTSD symptoms were assessed using the Clinician-Administered PTSD Scale. Cortical thickness and subcortical volumes were analyzed using the FreeSurfer image analysis package. Thickness of the paracentral and posterior cingulate regions was positively associated with PTSD severity in the EL-Trauma+ group and negatively in the Control group. In the EL-Trauma+ group, both the right amygdala and the left hippocampus were positively associated with PTSD severity. This study illustrates a possible influence of early life trauma on the vulnerability of specific brain regions to stress. Changes in neural morphometry may provide information about the emergence and maintenance of symptoms in individuals with PTSD.

Poor performance validity predicts clinical characteristics and cognitive test performance of OEF/OIF/OND Veterans in a research setting.

This study examined the performance of 198 Veteran research participants deployed during Operation Enduring Freedom, Operation Iraqi Freedom, and/or Operation New Dawn (OEF/OIF/OND) on four measures of performance validity: the Medical Symptom Validity Test (MSVT), California Verbal Learning Test: Forced Choice Recognition (FCR), Reliable Digit Span (RDS), and TOVA Symptom Exaggeration Index (SEI). Failure on these performance validity tests (PVTs) ranged from 4% to 9%. The overall base rate of poor performance validity, as measured by failure of the MSVT in conjunction with an embedded PVT (FCR, RDS, SEI), was 5.6%. Regression analyses revealed that poor performance validity predicted cognitive test performance and self-reported psychological symptom severity. Furthermore, a greater prevalence of traumatic brain injury (TBI), Post-Traumatic Stress Disorder (PTSD), co-morbid TBI/PTSD, and other Axis I diagnoses, was observed among participants with poor effort. Although poor performance validity is relatively uncommon in a research setting, these findings demonstrate that clinicians should be cautious when interpreting psychological symptoms and neuropsychological test performance of Veteran participants who fail effort measures.

The Boston Assessment of Traumatic Brain Injury-Lifetime (BAT-L) semistructured interview: evidence of research utility and validity.

OBJECTIVE: Report the prevalence of lifetime and military-related traumatic brain injuries (TBIs) in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) veterans and validate the Boston Assessment of TBI-Lifetime (BAT-L). SETTING: The BAT-L is the first validated, postcombat, semistructured clinical interview to characterize head injuries and diagnose TBIs throughout the life span. PARTICIPANTS: Community-dwelling convenience sample of 131 OEF/OIF veterans. DESIGN: TBI criteria (alteration of mental status, posttraumatic amnesia, and loss of consciousness) were evaluated for all possible TBIs, including a novel evaluation of blast exposure. MAIN MEASURES: BAT-L, Ohio State University TBI Identification Method (OSU-TBI-ID). RESULTS: About 67% of veterans incurred a TBI in their lifetime. Almost 35% of veterans experienced at least 1 military-related TBI; all were mild in severity, 40% of them were due to blast, 50% were due to some other (ie, blunt) mechanism, and 10% were due to both types of injuries. Predeployment TBIs were frequent (45% of veterans). There was strong correspondence between the BAT-L and the OSU-TBI-ID (Cohen κ = 0.89; Kendall τ-b = 0.95). Interrater reliability of the BAT-L was strong (κs >0.80). CONCLUSIONS: The BAT-L is a valid instrument with which to assess TBI across a service member's lifetime and captures the varied and complex nature of brain injuries across OEF/OIF veterans' life span.

Driving simulator performance of veterans from the Iraq and Afghanistan wars.

Driving simulator performance was examined in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) Veterans to objectively evaluate driving abilities among this cohort who self-report poorer driving safety postdeployment. OIF/OEF Veterans (n = 25) and age- and education-matched civilian controls (n = 25) participated in a 30 min driving simulator assessment that measured the frequency of minor, moderate, and severe driving errors. Frequency of errors in specific content domains (speed regulation, positioning, and signaling) was also calculated. All participants answered questions about number of lifetime traffic "warnings," moving violation tickets, and accidents. Veterans completed the Posttraumatic Stress Disorder (PTSD) Checklist-Military Version. On the driving simulator assessment, Veterans committed more minor, moderate, severe, and speeding errors and reported poorer lifetime driving records than the civilian control group. Exploratory analyses revealed an association between increasing errors on the driving simulator with increasing symptoms of PTSD, although statistically this correlation did not reach significance. These findings suggest that Veterans perform more poorly on an objective evaluation of driving safety and that the presence of PTSD could be associated with worse performance on this standardized driving simulator assessment.

PTSD modifies performance on a task of affective executive control among deployed OEF/OIF veterans with mild traumatic brain injury.

Individuals with post-traumatic stress disorder (PTSD) show a cognitive bias for threatening information, reflecting dysregulated executive control for affective stimuli. This study examined whether comorbid mild Traumatic Brain Injury (mTBI) with PTSD exacerbates this bias. A computer-administered Affective Go/No-Go task measured reaction times (RTs) and errors of omission and commission to words with a non-combat-related positive or negative valence in 72 deployed United States service members from the wars in Iraq and Afghanistan. Incidents of military-related mTBI were measured with the Boston Assessment of Traumatic Brain Injury-Lifetime. PTSD symptoms were measured with the Clinician-Administered PTSD Scale. Participants were divided into those with (mTBI+, n = 34) and without a history of military-related mTBI (mTBI-, n = 38). Valence of the target stimuli differentially impacted errors of commission and decision bias (criterion) in the mTBI+ and mTBI- groups. Specifically, within the mTBI+ group, increasing severity of PTSD symptoms was associated with an increasingly liberal response pattern (defined as more commission errors to negative distractors and greater hit rate for positive stimuli) in the positive compared to the negative blocks. This association was not observed in the mTBI- group. This study underscores the importance of considering the impact of a military-related mTBI and PTSD severity upon affective executive control.

Clinical and demographic factors associated with employment status in US military veterans returning from Iraq and Afghanistan.

OBJECTIVE: To determine the association between clinical and demographic factors with employment status in post-deployment US military veterans returning from Iraq and Afghanistan. PARTICIPANTS: 169 OIF/OEF veterans seen at a post-deployment clinic between December of 2009 and May of 2010. METHODS: Data was collected retrospectively on employment status, age, marital status, gender, pre-deployment education, ratings of sleep disturbance, pain, and depression, and mild traumatic brain injury (mTBI) or PTSD diagnosis. RESULTS: Unemployment was highly prevalent in this sample (45%). Of the demographic and clinical factors examined, only a self-report of global depression severity was significantly associated with a higher prevalence of unemployment in multivariate analysis (odds ratio [OR] 0.21, 95% confidence interval [CI] 0.10-0.47). Age greater than 40 demonstrated a positive association with employment status that was of borderline statistical significance ([OR] 2.8, 95% confidence interval [CI] 1.0-8.1). Prior diagnoses of mTBI or PTSD, and current sleep or pain symptoms, were not associated with employment status. CONCLUSIONS: Individuals with more severe self-reported depression had a higher prevalence of unemployment. Future prospective studies are needed to better understand which factors determine employment status in returning veterans.

Web-based assessment of visual and visuospatial symptoms in Parkinson's disease.

Visual and visuospatial dysfunction is prevalent in Parkinson's disease (PD). To promote assessment of these often overlooked symptoms, we adapted the PD Vision Questionnaire for Internet administration. The questionnaire evaluates visual and visuospatial symptoms, impairments in activities of daily living (ADLs), and motor symptoms. PD participants of mild to moderate motor severity (n = 24) and healthy control participants (HC, n = 23) completed the questionnaire in paper and web-based formats. Reliability was assessed by comparing responses across formats. Construct validity was evaluated by reference to performance on measures of vision, visuospatial cognition, ADLs, and motor symptoms. The web-based format showed excellent reliability with respect to the paper format for both groups (all P's < 0.001; HC completing the visual and visuospatial section only). Demonstrating the construct validity of the web-based questionnaire, self-rated ADL and visual and visuospatial functioning were significantly associated with performance on objective measures of these abilities (all P's < 0.01). The findings indicate that web-based administration may be a reliable and valid method of assessing visual and visuospatial and ADL functioning in PD.

Prevalence and characteristics of driving difficulties in Operation Iraqi Freedom/Operation Enduring Freedom combat returnees.

We studied the prevalence and characteristics of self-reported driving difficulties and examined their association with traumatic brain injury (TBI) and/or posttraumatic stress disorder (PTSD) in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) veterans who were seen at a Department of Veterans Affairs outpatient polytrauma clinic. In this study, we used a brief driving questionnaire and chart reviews to assess the prevalence and characteristics of driving difficulties in the following four groups of patients: TBI only, PTSD only, TBI + PTSD, and Neither (neither TBI nor PTSD). Compared with before deployment, 93% of OIF/OEF veterans seen in the polytrauma clinic reported more difficulties with driving in at least one domain, with the most common areas of difficulty being (1) problems with anger or impatience (82%), (2) general driving difficulties (65%), and (3) experiences with near misses (57%). Patients with PTSD (with or without TBI) reported the most significant driving impairments, whereas respondents with a history of only TBI endorsed driving difficulties similar to veterans without either diagnosis. Qualitative analysis of veterans' comments also revealed similar patterns. Self-reported driving problems were common among OIF/OEF returnees. Respondents who had a diagnosis of PTSD (with or without TBI) reported the most severe driving difficulties since returning from deployment. The association between PTSD and driving problems warrants further investigation.

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

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.