The role of cognitive reserve in cognitive aging: what we can learn from Parkinson's disease.

Parkinson's disease (PD) typically occurs in elderly people and some degree of cognitive impairment is usually present. Cognitive reserve (CR) theory was proposed to explain the discrepancy between the degree of brain pathologies and clinical manifestations. We administered a comprehensive neuropsychological battery to 35 non-demented participants affected by PD. All participants underwent also the Cognitive Reserve Index questionnaire and the Brief Intelligence Test as proxies for CR. Relationships between CR and cognitive performance were investigated by linear regression analyses, adjusting for significant confounding factors. At linear regression analyses, higher CR scores were independently associated with a better performance on Word Fluency (p ≤ 0.04) and Digit Span (backward) (p ≤ 0.02); no associations were observed between CR and other cognitive tests. Our data provide empirical support to the relation between CR and cognitive impairment in PD. In particular, this study suggests that CR may have greater effects on the cognitive areas mostly affected in PD as executive functions.