Introduction: Nonmotor symptoms, including depression, anxiety, apathy, and cognitive dysfunction, are common in Parkinson’s disease (PD). Although a link between mood symptoms and cognitive impairment in PD has been theorized vis-à-vis striatal dopamine depletion, studies have been inconsistent regarding the relationship between mood symptoms and cognitive function. Inconsistencies may reflect the cross-sectional nature of previous studies. The current study examined the bidirectional longitudinal relationship between mood and cognition. Method: Data were obtained from 310 individuals newly diagnosed with PD, who were followed up to 4 years (baseline, 1st, 2nd, 3rd, and 4th annual follow-ups). Apathy, anxiety, depressive symptoms, motor severity, and neurocognitive functioning were assessed at each annual assessment. The longitudinal relationship between apathy, anxiety, depressive symptoms, and cognition was analyzed with multilevel models. Results: Over the 4-year period, more severe depressive symptoms were related to worse performance on tasks of processing speed, verbal learning, and verbal delayed recall. Additionally, there was a significant Depression × Time interaction, suggesting that individuals with more severe depressive symptoms experience more rapid declines in global cognitive functioning and verbal learning. Apathy and anxiety were not significantly related to performance in any cognitive test. Lagged models revealed that changes in depression precede declines in working memory, verbal learning, delayed verbal recall, and global cognition. Conclusion: Findings suggest depressive symptoms may be a harbinger for future cognitive decline among individuals with PD.

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Objectives: Meta-tasking (MT) is an aspect of executive functioning (EF) that involves the ability to branch (i.e., to apply “if-then” rules) and to effectively interleave sub-goals of one task with sub-goals of another task. As such, MT is crucial for successful planning, coordination, and execution of multiple complex tasks in daily life. Traditional tests of EF fail to adequately measure MT. This study examined whether Condition 4 of the Color-Word Interference Test (CWIT-4; the inhibition/switching condition that requires branching) predicted MT beyond Condition 3 (CWIT-3; inhibition-only condition) and beyond other subtests from the Delis–Kaplan Executive Function System (D-KEFS) that have a switching condition. Method: Ninety-eight non-Hispanic white community-dwelling older adults completed the first four subtests of the D-KEFS and an ecologically valid measure of MT. Results: Time to completion and total errors on CWIT-4 accounted for variance in MT above and beyond CWIT-3 and beyond the switching conditions of other D-KEFS subtests. Results remained virtually unchanged when controlling for demographics and general cognitive status. Conclusions: Among older adults, CWIT-4 is more strongly associated with MT than other D-KFES tasks. Future research should examine whether CWIT-4 relates to lapses in instrumental activities of daily living among older adults above and beyond other EF tests.

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Objective Intra-individual variability (IIV) has shown utility in characterizing cognitive dysfunction in conditions including traumatic brain injury and dementia, but has been less studied in stroke. This study examined IIV in physical medicine and rehabilitation patients with stroke and mixed neurologic conditions. Method Participants (N = 95) were 40% female and 83% white with average age and education of 46 (SD = 13) and 14 (SD = 2) years, respectively. Participants completed an outpatient evaluation using a flexible battery of up to 33 common neuropsychological measures. Participants were grouped by diagnosis: stroke and other cerebrovascular events (e.g., aneurysm; 58%), and mixed neurologic conditions (e.g., anoxia, dementia; 42%). Adequate performance validity was determined on the basis of embedded and freestanding validity measures. Test battery scores were converted to T scores. Cases with four or more scores below 36 T were identified as impaired. Measures of IIV were calculated including overall test battery mean (OTBM), test battery standard deviation (SD), kurtosis, skew, range, and unbiased coefficient of variation (UCV). Groups were compared on IIV measures and impairment. Results Diagnostic groups were not significantly different on IIV measures. Impairment rates were not different in stroke (78%) and mixed (68%) groups. Unimpaired cases showed significantly higher OTBM, and significantly lower SD, range, and UCV (all p’s < .01); kurtosis and skew were not significantly different. Conclusions IIV markers of cognitive dysfunction in stroke are similar to those observed in dementia and other neurologic conditions. Further study of the clinical application of IIV measures is needed.