Premorbid exercise engagement and motor reserve in Parkinson's disease.

BACKGROUND Life-long experiences of cognitive activity could enhance cognitive reserve, which may lead individuals to show less cognitive deficits in Alzheimer's disease, despite similar pathological changes. We performed this study to test whether premorbid physical activity may enhance motor reserve in Parkinson's disease (PD) (i.e., less motor deficits despite similar degrees of dopamine depletion). METHODS We assessed engagement in premorbid leisure-time exercise among 102 drug naive PD patients who had been initially diagnosed at our hospital by dopamine transporter scanning. Patients were classified into tertile groups based on the frequency, duration, and intensity of the exercises in which they participated. RESULTS Among patients with mild to moderate reductions in striatal dopaminergic activity (above the median dopaminergic activity), the exercise group of the highest tertile showed significantly lower motor scores (i.e., fewer motor deficits, 15.53 ± 6.25), despite similar degrees of dopamine reduction, compared to the combined group of the middle and the lowest tertiles (21.57 ± 8.34, p = 0.01). Nonetheless, the highest tertile group showed a more rapid decline in motor function related to reductions in striatal dopaminergic activity than the other two groups (p = 0.002 with the middle tertile group and p = 0.001 with the lowest tertile group). CONCLUSIONS These results suggest that engagement in premorbid exercise acts as a proxy for an active reserve in the motor domain (i.e., motor reserve) in patients with PD.