Description:
<jats:p>Although Parkinson’s disease (PD) is a movement disorder in which tremor, rigidity and bradykinesia constitute the cardinal signs of the disease, it is increasingly recognised to be associated with a wide range of motor and non-motor features. Population-based studies demonstrate that the motor course in PD is generally slowly progressive, with average annual progression rates of ≤3%. However, there is remarkable inter-individual variation in the clinical course of PD, with advanced age and predominant postural instability and gait difficulties being major risk factors for more rapid motor and cognitive decline. Around 20–40% of patients exhibit subtle cognitive deficits at diagnosis. These usually worsen over time and progress into dementia, which approximately 80% of PD subjects develop during the course of their disease. Population-based studies indicate rather high frequencies of other non-motor symptoms in moderate to advanced stages, such as depression, fatigue, apathy, sleep disorders and autonomic dysfunction, although prevalence rates often are lower than those observed in clinic-based studies. However, as several population-based studies were cross-sectional, uncontrolled and did not use currently accepted rating scales or diagnostic criteria, the relative risk and clinical course of many disease-related features remain unclear in the general PD population. Further population-based studies are warranted in order to extend current knowledge on the clinical course in representative PD cohorts.</jats:p>