THE TEMPORAL VARIANT OF FRONTOTEMPORAL DEMENTIA

Frontotemporal dementia is a dementia syndrome with diverse clinical c haracteristics. Based upon clinical parameters and single photon emiss ion computed tomography, we identified 47 frontotemporal dementia subj ects. In 10 of these 47 the primary site of brain dysfunction was ante rior temporal and orbital-frontal with other frontal regions relativel y spared In this temporal lobe variant (TLV) of frontotemporal dementi a, five of the subjects had more severe left-sided, and five had more right-sided, hypoperfusion. The clinical, neuropsychological and neuro psychiatric features of predominanly left-sided (LTLV) and right-sided (RTLV) TLV subjects are discussed and contrasted with more frontal pr esentations of frontotemporal dementia. In LTLV, aphasia was usually t he first and most severe clinical abnormality. RTLV patients presented with behavioural disorders characterized by irritability, impulsivene ss, bizarre alterations in dress, limited and fixed ideas, decreased f acial expression and increased visual alertness, These findings sugges t that: (i) frontotemporal dementia is clinically heterogeneous with b itemporal and inferior frontal lobe dysfunction contributing to the cl inical presentation; (ii) behavioural disturbance and aphasia are the most prominent features of predominantly temporal subtypes of frontote mporal dementia; (iii) the right and left anterior temporal regions ma y mediate different behavioural functions. The results of this study s uggests that TLV offers a valuable source of information concerning th e behavioural disorders seen with combined anterior temporal and infer ior frontal lobe dysfunction.