How Common is Cognitive Decline in Parkinson’s?

A new study finds that cognitive impairment is a frequent and rapidly progressing symptom of Parkinson’s disease (PD). About half of the participants who had PD for an average of five years and had normal cognition at the beginning of the study developed mild cognitive impairment (MCI) within six years – about 11 years after PD diagnosis. Those few who developed MCI progressed to dementia within five more years. The results appear in the September 11 online edition of Neurology.