Impaired cognitive performance and hippocampal atrophy in Parkinson disease

Dementia is common in Parkinson disease (PD). Since magnetic resonance imaging has been used, hippocampal atrophy has been shown in PD patients with or without dementia. In this study we sought the correlation of cognitive decline with bilateral hippocampal volume in PD patients.

Thirty-three patients with diagnosis of idiopathic PD and 16 healthy subjects were included in this study. PD patients were divided into two groups as normal cognitive function and mild cognitive impairment (MCI). The Mini-Mental State Examination and detailed cognitive assessment tests were performed for all patients for cognitive analyses. Depression was excluded by the Geriatric Depression Scale.

The mean onset age of disease was 55 years for PD patients without dementia and 59 for PD patients with MCI. According to the Hoehn-Yahr scales, 24% of patients had grade 1, 58% had grade 2, and 18% had grade 3 disease. Right and left hippocampal volumes decreased along with cognitive test scores in PD patients. Increased right hippocampal volume was correlated with forward number test in the MCI-PD group.

These findings suggest that memory deficit is associated with hippocampal atrophy in PD patients.