Cognitive impairments are among the non-motor symptoms in patients with Parkinson’s disease (PD). Understanding the cognitive impairments in patients with PD may be critical for developing effective rehabilitation interventions. The purpose of this study is to assess cognitive function in patients with PD using the Wechsler Adult Intelligence Scale-third edition (WAIS-III) and the Wechsler Memory Scale-revised (WMS-R), and investigate how cognitive impairments relate to progression of disease in patients with PD according to the Hoehn and Yahr (HY) stages.
Seventy-eight patients with PD participated in the present study. Our study consisted of patients in the following HY groups: I (no disability, n=11), II (mild, n=34), III (moderate, n=26), and IV-V (severe, n=7). Cognitive function was assessed using the WAIS-III and the WMS-R.
The verbal memory was significantly higher in group I (106.4±12.0) than in the other groups (II: 90.5 ±14.0, III: 89.9±16.9, IV-V: 89.6 ±11.4). Visual memory and delayed recall were similar to the results seen with verbal memory, however, the differences between groups were not statistically significant. The full-scale IQ was not significantly different (I: 107.3±8.1, II: 96.9±18.2, III: 96.7±14.8, IV-V: 91.7±9.5).
These results suggest that a comprehensive assessment focused on memory impairments is important for applying the appropriate interventions in patients with early-stage PD.