Physical inactivity links depressive symptoms and cognitive functioning among individuals with Parkinson’s disease.

Abstract

Objective: Parkinson’s disease (PD) is a neurodegenerative disorder caused by disruption of dopamine-producing cells. PD is associated with motor symptoms and nonmotor symptoms including depression and cognitive impairment. Past research suggests an association between depression and cognitive impairment in PD. Physical activity may have a therapeutic effect on both depression and cognitive impairment. The present study investigates if physical activity mediates the association between depressive symptoms and cognition in a longitudinal sample of individuals with PD. Method: Participants include individuals newly diagnosed with PD (N = 487) enrolled in the Parkinson’s Progression Marker Initiative (PPMI). Participants completed an array of neuropsychological tests over the course of 5 years, as well as questionnaires of depression and physical activity. Between-person and within-person effects of depression and cognition mediated through physical activity were analyzed using structural equation modeling. Results: A significant direct effect demonstrated depression was associated with worse global cognitive functioning. Furthermore, there was a significant indirect within-person effect, indicating that physical activity fully mediated the association between depression and cognition. Individuals who became more depressed over time became less physically active and subsequently experienced cognitive decline over the 5-year period. Conclusions: Findings have implications for prognostic detection and/or the role of physical activity interventions to buffer effects of depression on cognitive impairment among individuals diagnosed with PD. Physical interventions may potentially be implemented among depressed persons to preserve cognitive functioning. Worsened depression early during PD may be a risk factor for inactivity and cognitive diminishment.

A Systematic Review of the Association between Sedentary Behavior and Non-Motor Symptoms of Parkinson’s Disease

“…Of these, 243 were considered irrelevant, and 37 studies underwent full-text screening. Finally, 7 studies(13)(24)(25)(26)(27)(28)(29) were found eligible for systematic review and included in the data extraction and narrative synthesis. The selection process is summarized in a PRISMA flowchart (Figure 1).…”

“…Out of the seven studies, six investigated the impact of sedentary behavior on cognition (13)(27)(26)(24)(25)(28). Three of these studies focused exclusively on cognition(28)(27)(25), while the other three assessed depression and other factors in addition to cognition(13)(26)(24). All the studies were observational studies encompassing different study designs.…”

“…Two studies assessed depression in addition to the cognitive impairment in individuals with PD(26)(24). One study reported that depression led to sedentary behavior, which in turn, led to cognitive decline over time(26).…”

“…Two studies assessed depression in addition to the cognitive impairment in individuals with PD(26)(24). One study reported that depression led to sedentary behavior, which in turn, led to cognitive decline over time(26). This suggests that lack of physical activity might play a role in depression and its eventual impact on cognitive decline(26).…”

“…These findings make it difficult to establish causation. Moreover, it has been reported that mood and thought disorders such as apathy and anxiety may increase the risk of physical inactivity (26). Additionally, factors such as female gender, older age, and a decline in overall physical capacity are important determinants of sedentary behavior (31).…”