Executive dysfunction and everyday functioning deficits in Parkinson's Disease
Authors:   , Brennan Laura , Schultheis Maria Teresa 
Published: September 2022

Cognitive impairment is increasingly recognized as a characteristic of Parkinson's disease (PD). Executive dysfunction is recognized as a significant facet of cognitive impairment in PD across studies, while research in other cognitive domains, such as such as attention, memory, and visuo-spatial functioning, have had mixed results. Cognitive decline in PD patients may lead to impairments in everyday functioning, or the ability to perform activities of daily living, and decreased quality of life. Although the relationship between motor impairments and global cognitive impairment on everyday functioning in PD has been explored, the impact of domain-specific deficits is not well understood. The neuropathology of PD, including deficits in the basal ganglia and associated cortical feedback loops, has been suggested to play a role in executive dysfunction. These brain structures have been implicated in executive dysfunction and everyday functioning in normal aging samples as well. Using a retrospective database, this study consisted of two specific aims; 1) to examine neuropsychological correlates of everyday functioning in PD, and 2) to examine the clinical utility of two commonly used measured of global cognitive status in relation to everyday functioning. It was hypothesized that initiation/perseveration and working memory, sub-domains of executive functioning, would demonstrate the strongest relationship to everyday functioning in PD compared to other cognitive domains. It was hypothesized that two commonly used measures of global cognition would be significantly correlated with measures of everyday functioning. The data used in this study was collected as part of an ongoing longitudinal cohort study, conducted through Parkinson's Disease and Movement Disorders Center (PDMDC), an outpatient neurology clinic in Philadelphia, Pennsylvania. Demographics were coded, and the measures analyzed in the present study included: 1) neuropsychological measures of global cognition (Mini-Mental State Examination, MMSE; Dementia Rating Scale-2, DRS-2), attention (DRS-2 Attention subscale), memory (Hopkins Verbal Learning Test - Revised, HVLT-R, delayed recall; DRS-2 Memory subscale), visuo-spatial/visuo-perceptual functioning (Judgment of Line Orientation, JOLO; DRS-2 Construction subscale), and subdomains of executive functioning (phonemic verbal fluency; clock draw copy; DRS-2 Initiation/Perseveration subscale); 2) everyday functional status via care-giver report (Alzheimer's Disease Cooperative Study -Activities of Daily Living Inventory, ADCS-ADL); and 3) PD motor disability (Hoehn & Yahr). In a sample of 181 participants with confirmed PD, partial correlation analyses indicated that measures of global cognition (MMSE, r=0.25, p<.01; DRS-2, r=0.27, p<.01), measures of visuo-spatial/visuo-perceptual abilities (JOLO, r=0.20, p<.05; DRS-2 Construction r=0.20, p<.05), and sub-domains of executive functioning including initiation/perseveration (DRS-2 Initiation/Perseveration, r=0.16, p<.05), and working memory/tasking monitoring (phonemic verbal fluency, r=0.18, p<.05), are related to everyday functioning in PD. Attention and memory were not significantly related to everyday functioning. A multiple regression analysis of three tests of executive functioning, including measures of working memory/task monitoring (verbal fluency), planning/execution (clockdraw copy), and initiation/perseveration (DRS-2 Initiation/Perseveration subscale), revealed the model to have significant predictive value in everyday functioning in PD (R = .52, F (3, 152) = 18.88, p < .001). Several neuropsychological assessment tools that require 20 minutes or less to administer demonstrated significant relationships with everyday functioning in PD, including measures of sub-domains of executive functioning (initiation/perseveration, working memory), visuo-spatial/visuo-perceptual functioning, and two commonly used clinical measures of global cognition. High correlations demonstrated between the MMSE, DRS-2 and everyday functioning supports continued use in the clinic. Future research should further explore the clinical utility of these measures, in an effort to inform everyday functioning status and integrative treatment approaches for PD patients, and provide a foundation for the development of PD-specific assessment measures of both global cognition and everyday functioning.