CHANGE IN COGNITIVE FUNCTION IN IDIOPATHIC PARKINSON DISEASE

Objective: To study the effects of Parkinson disease (PD) on cognitive function by determining the frequency and amount of change in Mini-Me ntal State Examination (MMSE) performance. Design: During a 4-year per iod, 77 patients with idiopathic PD and 43 normal elders were administ ered a neuropsychological lest battery twice at 2 years apart. Results : A 4-point score difference on the MMSE was the amount that was stati stically calculated to be a significant difference at the .05 probabil ity level. Using this metric, 17 (22%) patients with PD had a change i n their MMSE performance during a 2-year period. Fifteen individuals p erformed poorer, and 2 individuals improved. Using the same metric, no normal subjects changed in their MMSE performance. The groups of pati ents with PD who had a change and did not have a change in their MMSE performance were not characterized by significant differences in their years of education, duration of illness, age at onset, age at test ti me 1, estimated premorbid intelligence, Hamilton Psychiatric Rating Sc ale for Depression score at test time 1, or Unified Parkinson's Diseas e Rating Scale score. The singular difference was the higher frequency of change that was found in subjects who were taking dopamine agonist s at the second test time. Conclusion: A change in cognitive function id patients with PD, as measured by a change of 4 points or more in th eir MMSE performance, was observed in only 22% of a sample of 77 patie nts with idiopathic PD during a 2-year period.