Fluency Performance Patterns in Alzheimer's Disease and Parkinson's Disease

This study compared 38 patients with Alzheimer's disease, 20 patients with Parkinson's disease, and 51 normal controls on nonverbal, semantic, and phonological fluency tasks. Semantic and nonverbal fluencies declined significantly with age. The AD group was impaired on all fluency measures, with the greatest impairments on nonverbal and semantic fluency. The PD group was impaired on nonverbal and semantic fluencies. Differences observed in semantic fluency between the AD and PD groups could not be accounted for by dementia severity. Motor disability did not account for the PD nonverbal fluency deficit. This study provides evidence for a semantic-based impairment in AD and suggests that PD fluency deficits are primarily cognitive rather than motor in nature.