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Variations in regional SPECT hypoperfusion and clinical features in frontotemporal dementia

Objective: To characterize the presenting clinical features for frontotemporal dementia (FTD) and contrast them with the degree of frontal and temporal hypoperfusion on SPECT imaging. Methods: The authors evaluated 74 patients who eventually met Consensus Criteria for the FTD form of frontotemporal lobar degeneration (excluding primary progressive aphasia and semantic dementia) on 2-year follow-up. On first presentation, these patients had undergone both an FTD Inventory for 12 features based on core and supportive Consensus Criteria and SPECT imaging. The initial clinical diagnostic features were contrasted with variations in regional SPECT hypoperfusion. Results: The patients with FTD had more hypoperfusion in the right frontal lobe than in other regions; the subgroup of 25 patients who met Consensus Criteria from the first presentation had the most right frontal hypoperfusion. Frontal lobe involvement was associated with significant apathy, whereas temporal lobe involvement was associated with hypomania-like behavior. Right frontal lobe hypoperfusion further predicted loss of insight, environmental dependency, and stereotyped behaviors. Other associations included left frontal hypoperfusion with a decline in personal hygiene and left temporal hypoperfusion with compulsions and mental rigidity. Conclusions: On first presentation, frontotemporal dementia (FTD) is disproportionately a right frontal disease evident on behavioral measures and on SPECT. Nonetheless, patients with FTD can initially present with further regional differences in clinical diagnostic features, such as apathy with bifrontal hypoperfusion and hypomania-like behaviors with anterior temporal involvement.