Behavior in degenerative dementias: mood disorders, psychotic symptoms and predictive value of neuropsychological deficits.

We studied mood disorders (MD) and psychotic symptoms (PS) in patients with fronto -temporal dementia (FTD) and Alzheimer's disease (AD) by means of different diagnostic instruments. These were: a subjective scale (subsets of survey psychiatric assessment schedule: SPAS), an objective scale (subsets of neuropsychiatric inventory: NPI) and a projective task (Wartegg completion task: WCT). A general tendency of NPI to over estimate the presence of symptoms compared to SPAS was observed, but distribution and severity of symptoms were quite homogeneous in the two dementia-groups, independently of the diagnostic scales. At variance with the scales, the WCT showed a more severe impairment in FTD than in AD. The regression analysis selected neuropsychological models able to predict behavioral disorders only in FTD, in particular, a planning deficit predicted PS. These data confirm the hypothesis that a damage in the frontal areas constitutes the neurobiological basis of PS in degenerative brain diseases. Furthermore, they suggest that mostly in FTD, behavioral disorders, as well as cognitive deficits, should be considered a direct expression of neural damage.