Cognitive and behavioral differentiation of frontal lobe degeneration of the non-Alzheimer type and Alzheimer's disease.

Neuropsychological differences between 14 patients with a clinical diagnosis of frontal lobe degeneration of non-Alzheimer type (FLD) and 15 patients with a clinical diagnosis of Alzheimer's disease (AD) were studied. The most efficient psychometric predictors of FLD were Digit Symbol, estimation tasks, word list recall, and particularly the FAS word fluency test. Behavioral predictors of FLD and AD showed a double dissociation: regression and impulsivity characterized FLD, whereas lack of motivation and slowness were typical of AD. Cognitive and behavioral differences between groups were not related to the degree of dementia, as measured by Mini Mental State Examination, indicating that differences remained during progression of the diseases.