Gender-related dissociations of categorical fluency in normal subjects and in subjects with Alzheimer's disease.

Semantic fluency tasks, with the categories of birds and furniture as stimuli, were administered to normal subjects and patients with Alzheimer's disease (AD). Normal subjects showed a gender-related double dissociation consistent with the literature data because men were more fluent with the birds category and women with the furniture category. Also, patients with AD showed a Gender x Category interaction, but the double dissociation between birds and furniture was not present because of a prevalent impairment of the living category birds that was irrespective of gender. This pattern of impairment in patients with AD was independent from the disease stage. The authors conclude that (a) gender-related categorical effects cannot be considered as inborn, sex-related cognitive differences but as familiarity effects and (b) both lesion-related and familiarity-related factors must be taken into account to explain category-specific effects of patients with brain damage and patients with AD.