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INTRODUCTION: Cognitive dysfunction is common in Parkinson's disease (PD) and associated with reduced functional abilities and increased dependence. To date, however, little is known about the relationship between performance of instrumental activities of daily living (IADLs) and cognitive stages in PD, and there are conflicting reports as to whether declines in specific cognitive domains predict IADL impairment. METHODS: Participants with PD were drawn from the Pacific Udall Center and included in the study if both participant and study partner IADL ratings and cognitive tests were completed (n = 192). Logistic regression analyses were performed to determine whether participant and/or study partner rating predicted mild cognitive impairment or dementia. Correlations are reported for the relationship between participant/study partner IADL reports as well as for specific cognitive tests. RESULTS: Although both participant and study partner ratings of IADL performance were associated with a diagnosis of PD with dementia, only participant self-rating of functional ability was significantly associated with a diagnosis of PD with mild cognitive impairment. Functional ability correlated most strongly with measures of processing speed, auditory working memory, and immediate verbal recall for both the participant and study partner ratings. CONCLUSION: For participants with PD in the early stages of cognitive decline, self-rating may be more sensitive to the impact of cognitive changes on IADL function than ratings made by a knowledgeable study partner. Changes in executive function, processing speed, and learning may indicate a higher likelihood of IADL impairment. Careful assessment of cognition and IADL performance is recommended to permit individualized interventions prior to significant disability.
RESUMEN
Introduction: Cognitive impairment is a common symptom of Parkinson's disease (PD) associated with reduced quality of life and a more severe disease state. Previous research has shown an association between visuospatial dysfunction and worse disease course; however, it is not clear whether this is separable from executive dysfunction and/or dementia. This study sought to determine whether distinct cognitive factors could be measured in a large PD cohort, and if those factors were differentially associated with other PD-related features, specifically to provide insight into visuospatial dysfunction. Methods: Non-demented participants with PD from the Pacific Udall Center were enrolled (n = 197). Co-participants (n = 104) completed questionnaires when available. Principal components factor analysis (PCFA) was utilized to group the neuropsychological test scores into independent factors by considering those with big factor loading (≥.40). Linear and logistic regression analyses were performed to examine the relationship between the cognitive factors identified in the PCFA and other clinical features of PD. Results: Six factors were extracted from the PCFA: 1) executive/processing speed, 2) visual learning & memory/visuospatial, 3) auditory working memory, 4) contextual verbal memory, 5) semantic learning & memory, and 6) visuospatial. Motor severity (p = 0.001), mood (p < 0.001), and performance on activities of daily living scores (informant: p < 0.001, patient: p = 0.009) were primarily associated with frontal and executive factors. General sleep disturbance (p < 0.006) and hallucinations (p = 0.002) were primarily associated with visuospatial functioning and visual learning/memory. Conclusions: Motor symptoms, mood, and performance on activities of daily living were primarily associated with frontal/executive factors. Sleep disturbance and hallucinations were associated with visuospatial functioning and visual learning/memory only, over and above executive functioning and regardless of cognitive disease severity. These findings support that visuospatial function in PD may indicate a more severe disease course, and that symptom management should be guided accordingly.