ABSTRACT
PURPOSE To determine the impact of aging versus combined aging and disease on cognition in older adults with and without Parkinson’s disease (PD) who were volunteers for exercise based rehabilitation research.
METHODS We used a multiple linear regression approach to analyze cognitive outcome measures of rehabilitation volunteers with and without PD.
RESULTS Significant associations were identified between increased age and decreased performance on 8 of the 14 outcomes analyzed after controlling for false discovery rate. Of those 8 outcomes, multivariate regression analyses demonstrated an effect of disease on performance in only 4/8. In all cases, PD was associated with superior, rather than decreased performance after controlling for age. Results were unaffected by sex and education. Post-hoc comparison with available age norms demonstrated that differences between PD and Non-PD volunteers could be primarily attributed to the Non-PD group substantially underperforming versus age norms.
CONCLUSIONS In rehabilitative exercise studies using volunteers, many cognitive domains decline with increasing age, consistent with previous neuropsychological studies without a rehabilitation component. However, older “neurotypical” volunteers may potentially underperform PD volunteers after controlling for age. This may be an important design consideration for rehabilitation studies with cognitive outcomes.
IMPLICATIONS FOR REHABILITATION
An increasing number of rehabilitation studies incorporate cognitive outcomes.
Whether the overall cognitive profile of rehabilitation volunteers differs from that of neurotypical aging remains to be established.
Rehabilitation volunteers with Parkinson’s disease may outperform putatively neurotypical volunteers after controlling for covariates.
Cognitive impairments associated with PD in neuropsychological studies may not generalize to exercise rehabilitation volunteers.
