Semantic category and initial letter word fluency in left-brain-damaged patients

Fluency deficits have been found in different neuropsychological populations, and dissociation of letter initial and category fluency has been demonstrated in right-brain-damaged and Alzheimer patients. Studies on normal controls also indicate that letter initial and category fluency are supported by different brain regions. We studied letter initial and category fluency in 79 left-brain-damaged patients, 18 non-aphasic and 61 aphasic. Our results indicate that brain-damaged patients are significantly impaired in both fluency tasks compared to normal controls, and a difference between letter initial and category fluency emerges from our data. Firstly, only letter initial fluency is more impaired in aphasic than in non-aphasic patients; secondly, many aphasics have normal category fluency and pathological letter initial fluency but the reverse is seldom true and thirdly, only category fluency scores correlate with confrontation-naming scores. It is suggested that strategies to recover words based on a semantic or a phonological prompt are different. A semantic strategy is coherent with the organizational structure of the semantic system and corresponds to the normal way in which we recover words whereas a phonological strategy is quite unusual and it is not used for actual communication.