Acquired Extroversion Associated With Bitemporal Variant of Frontotemporal Dementia

Frontotemporal dementia (FTD) is characterized by alterations in personality. The nature of the personality changes depend on the localization of the pathology. The authors present three patients with acquired extroversion who met criteria for FTD. All three patients exhibited predominant bilateral temporal involvement as determined with functional neuroimaging. Possible mechanisms for acquired extroversion in bitemporal FTD include bilateral amygdalar damage with decreased interpersonal fear or sense of threat, orbitofrontal-ventromedial damage with social disinhibition, and relative sparing of dorsolateral frontal and anterior cingulate regions with preserved interpersonal agency. FTD can be a vehicle for unraveling the basis of personality characteristics such as the introversion/extroversion dimension.