Cognitive and motor reserve in Parkinson's disease: Two sides of the same coin?

Cognitive reserve (CR) and motor reserve (MR) are constructs that can explain why some people are more resilient than others to neurodegenerative diseases such as Parkinson's disease (PD). However, it is unclear whether these reserves exert domain-specific or cross-domain influences. This study investigated the predictive role of CR and MR on cognition and motor function, as well as possible cross-domain interactions. Fifty individuals with PD underwent neuropsychological and motor assessments and completed questionnaires measuring CR (Cognitive Reserve Index questionnaire, CRIq), MR (Motor Reserve Index questionnaire, MRIq), and current physical activity (Current Physical Activity questionnaire, CPAq). Multiple regression models were computed to assess the predictive value of total reserve indices on cognition, executive functions, and clinical motor outcomes. Correlation analyses were conducted between reserve sub-indices and cognitive and clinical motor variables. Total CRIq scores predicted global cognitive functioning and executive abilities, as well as age of onset and disease duration. However, total MRIq scores did not demonstrate any predictive value. The CPAq total score predicted executive functions and disease stage. Some CRIq and MRIq sub-indices were found to correlate with both cognitive and motor measures. CR influences multiple domains in PD, supporting cognition and counteracting clinical decline. The MRIq total score did not demonstrate any predictive value, but some correlations emerged between MRIq sub-indices and cognitive and motor measures. The CPAq revealed effects that crossed domains, indicating that ongoing physical activity may confer immediate protective effects. This highlights the importance of promoting cognitive and physical stimulating lifestyles to enhance resilience in PD.