Progression of gait disorder and rigidity and risk of death in older persons

Background: Bradykinesia, gait disturbance, rigidity, and tremor are common motor signs in old age. All of these signs are associated with increased morbidity and mortality, but the extent to which they are progressive is unknown. Methods: Study participants were 787 older Catholic clergy members without clinically diagnosed PD, related conditions, or dementia at baseline. They were evaluated annually for up to 7 years, with >95% follow-up participation by survivors. Evaluations included administration of a modified version of the motor portion of the Unified PD Rating Scale (UPDRS), from which previously established measures of the global UPDRS and four specific motor signs were derived. Scores represent the percent of the total possible UPDRS score obtained. Results: At baseline, the global UPDRS score ranged from 0 to 36.3 (mean+/-SD, 7.3+/-6.4). It increased by an average of 0.69 unit per year during follow-up, with more rapid progression in older persons, but there was wide variability with no progression in 21% of subjects and annual increases of up to 8.23 units in the remaining 79%. Of 129 persons who died, 106 had follow-up UPDRS data. In a proportional hazards model, risk of death was associated with both the level of the global UPDRS score at baseline and the annual rate of progression (both p<0.001). Overall, risk of death in subjects who had some worsening of the global UPDRS score was 2.93 times the rate among those without progression (95% CI, 1.32-6.50). Gait disorder/postural reflex impairment and rigidity worsened, but bradykinesia and tremor did not. Risk of death was associated with worsening of gait/posture but not with the other signs. Conclusion: Gait disorder and rigidity, as assessed with the modified UPDRS, are usually progressive in old age. Both the severity of the gait disorder and its rate of progression are strongly associated with risk of death.