Parkinson’s disease patients who develop anxiety early in their disease are at risk for reduced physical activity, which promotes further anxiety and cognitive decline, data from nearly 500 individuals show.

Anxiety occurs in 20%-60% of Parkinson’s disease (PD) patients but often goes undiagnosed, wrote Jacob D. Jones, PhD, of California State University, San Bernardino, and colleagues.

“Anxiety can attenuate motivation to engage in physical activity leading to more anxiety and other negative cognitive outcomes,” although physical activity has been shown to improve cognitive function in PD patients, they said. However, physical activity as a mediator between anxiety and cognitive function in PD has not been well studied, they noted.

In a study published in Mental Health and Physical Activity the researchers identified 487 adults with newly diagnosed PD within the past 2 years who were enrolled in the Parkinson’s Progression Markers Initiative. Participants were followed for up to 5 years and completed neuropsychological tests, tests of motor severity, and self-reports on anxiety and physical activity.

Anxiety was assessed using the State-Trait Anxiety Inventory-Trait (STAI-T) subscale. Physical activity was assessed using the Physical Activity Scale for the Elderly (PASE). Motor severity was assessed using the Unified Parkinson’s Disease Rating Scale-Part III (UPDRS). The average age of the participants was 61 years, 65% were men, and 96% were White.

Using a direct-effect model, the researchers found that individuals whose anxiety increased during the study period also showed signs of cognitive decline. A significant between-person effect showed that individuals who were generally more anxious also scored lower on cognitive tests over the 5-year study period.

In a mediation model computed with structural equation modeling, physical activity mediated the link between anxiety and cognition, most notably household activity.

“There was a significant within-person association between anxiety and household activities, meaning that individuals who became more anxious over the 5-year study also became less active in the home,” reported Jones and colleagues.

However, no significant indirect effect was noted regarding the between-person findings of the impact of physical activity on anxiety and cognitive decline. Although more severe anxiety was associated with less activity, cognitive performance was not associated with either type of physical activity.

The presence of a within-person effect “suggests that reductions in physical activity, specifically within the first 5 years of disease onset, may be detrimental to mental health,” the researchers emphasized. Given that the study population was newly diagnosed with PD “it is likely the within-person terms are more sensitive to changes in anxiety, physical activity, and cognition that are more directly the result of the PD process, as opposed to lifestyle/preexisting traits,” they said.

The study findings were limited by several factors, including the use of self-reports to measure physical activity, and the lack of granular information about the details of physical activity, the researchers noted. Another limitation was the inclusion of only newly diagnosed PD patients, which might limit generalizability.

“Future research is warranted to understand if other modes, intensities, or complexities of physical activity impact individuals with PD in a different manner in relation to cognition,” they said.

Jones and colleagues had no disclosures. The PPMI is supported by the Michael J. Fox Foundation for Parkinson’s Research and funding partners, including numerous pharmaceutical companies.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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