PD risk lowest in physically active men

Men who exercise vigorously have a lower risk of Parkinson disease (PD), according to a large prospective study. However, the study found no significant association between exercise and the risk of PD in women. The study population (48,574 men and 77,254 women) originated from two study cohorts: the Health Professionals Follow-up Study (HPFS) cohort, which was established in 1986, and included men aged 40-75 years; and the Nurses' Health Study (NHS) cohort which was established in 1976, and included women aged 30-55 years. Each participant answered a baseline questionnaire on disease history, dietary habits, and lifestyle practices. Biennial questionnaires were then used to collect data on lifestyle practices and record major medical events. The authors followed participants from baseline to the date of first PD symptoms, the date of stroke diagnosis or death, or the end of the follow-up (January 2000 for men and May 1998 for women).During follow-up, 253 men and 135 women were identified as new incident cases of PD. The authors found that, in men, overall physical activity was inversely associated with PD risk, and men who were the most physically active had a 30% lower PD risk than those who were least active. Further analyses showed that greater vigorous activity, but not moderate activity, was related to a lower risk of PD. Physical activity was not significantly associated with PD risk in women, although strenuous activity in early adulthood (18-22 years) was non-significantly associated with a lower PD risk.In the men and women who went on to develop PD, the authors observed a decline in physical activity greater than that attributable to ageing. Discussing this finding, they remark, "The preclinical decline of physical activity reflects the insidious nature of the disease and the unrecognized physiopathologic changes that may limit the patients' capability to tolerate vigorous exercises." They suggest that enhanced fatigue in PD patients may be associated with mitochondrial dysfunction or may reflect progressive loss of dopaminergic neurons in the CNS.The authors conclude that the link between physical exercise and PD risk in men suggests either that higher levels of exercise protect against PD or that men predisposed to PD tend to avoid strenuous physical activity in early adulthood. Reference...