Early stage of behavioral variant frontotemporal dementia: clinical and neuroimaging correlates

The early stages of behavioral variant frontotemporal dementia (bvFTD) are still not completely characterized. In a consecutive series of patients with probable bvFTD diagnosis confirmed by follow-up, we retrospectively evaluated the features at onset. Patients were reclassified according to presenting features and current diagnostic criteria into probable and possible bvFTD. The term "pre-bvFTD" was adopted for patients with cognitive and/or behavioral impairment not fulfilling bvFTD criteria and no deficits in activities of daily living. One hundred ninety-four subjects were included; at first visit, 70% (n = 136) patients were already classified as probable bvFTD. Of the remaining 30% (n = 58), 60% fulfilled criteria for possible bvFTD, while 40% did not, and were classified as pre-FTD. The neuropsychological pattern in possible bvFTD and pre-bvFTD was similar, although possible bvFTD showed more behavioral abnormalities. Pre-bvFTD subjects had frontotemporal gray matter atrophy, although less extensive than possible bvFTD. Conclusively, most bvFTD patients fulfill current diagnostic criteria at first admission, whereas a relatively small group is characterized by mild behavioral and/or cognitive abnormalities in spite of frontotemporal gray matter atrophy. Our preliminary findings will require a validation in prospective studies involving larger samples of patients.