HYPOKINESIA IN PARKINSONS-DISEASE - INFLUENCE OF AGE, DISEASE SEVERITY, AND DISEASE DURATION

The aim of this cross-sectional study was to compare the role of aging in measures reflecting diurnal activity and immobility in 60 parkinso nian patients with predominant features of hypokinesia and rigidity an d 100 healthy subjects aged 50 to 98 years. In the patients, we also s tudied the relation between disease duration and subjective and object ive measures of disease severity. Motor activity was recorded during 5 successive days at home with a wrist-worn activity monitor. For each subject, two mean measures reflecting the diurnal activity level and t he relative proportion of activity and immobility were calculated. Diu rnal measures of activity revealed in both groups a prominent absolute reduction of activity and an increase of the time spent without movem ent (''immobility'') with advancing age. Parkinsonian patients showed significantly lower values for both motor-activity measures than did t he healthy subjects. The rate of the age-related decline of both diurn al activity measures in both groups, however, is comparable. Disease d uration showed no relation with subjective and objective measures refl ecting disease severity. This study shows that if care is taken to con trol for disease severity, the rate of the age-related decline of meas ures reflecting diurnal activity and immobility is similar in both gro ups. The lack of relation between disease duration and subjective and objective measures of disease severity suggests that the rate of progr ession of Parkinson's disease can be reliably studied only by means of longitudinal studies.