Parkinson’s disease (PD) is characterized by motor and non-motor symptoms including cognitive, autonomic, sleep, and sensory disturbances. Cognitive impairment may occur in up to 80% of PD patients, and dementia in approximately 30%. The purpose of this study is to evaluate the frequency of cognitive impairment and the characteristics of cognitive deficits and to know the possibility of early detection of cognitive deficits in outpatient clinics with the questionnaire for patients and caregivers.

A total of 129 consecutive patients with idiopathic Parkinson’s disease were visited movement clinic from March 2006 to August 2006. Eighty-five patients performed cognitive test and questionnaires. All patients had motor symptoms with Hoehn and Yahr stage 0.5 to 3 (mean: 1.98±0.617), and evaluated with cognition by K-MMSE (Korean version of Mini-mental status examination), 7-MS (7-minutes screen test), and demographic features.

The frequency of cognitive impairment in PD patients was 44.7% (38/85), among them thirty (78.9%) patients complained memory disturbance. The characteristics of cognitive test were retrieval defect in memory, visuospatial dysfunction and categorical word fluency. With questionnaire, the complaint of memory decline and difficulties in activity of daily living (ADL) w ere important points of cognitive deficit in PD patients. However questionnaire did not showed significant correlation between complain of memory decline and cognitive deficit, only regular check with cognitive function test revealed the patient’s early cognitive impairment.

The cognitive impairment was frequent in PD patients. The characteristics of cognitive testing w ere retrieval defect in memory function and frontal executive dysfunction.