Progression in Frontotemporal Dementia: Identifying a Benign Behavioral Variant by Magnetic Resonance Imaging

Abstract

OBJECTIVE: To assess the clinical course and prognosis in patients with behavioral-variant frontotemporal dementia (FTD) lacking evidence of brain atrophy on magnetic resonance imaging (MRI). DESIGN: Patients were enrolled into this prospective cohort study over a period of 15 years; cognitive status, duration of symptoms, and behavioral indexes were recorded. Brain MRIs were rated using a standardized scale. SETTING: Regional early-onset dementia clinic. PARTICIPANTS: Thirty-one participants diagnosed clinically with behavioral-variant FTD. Intervention Rating of MRIs. MAIN OUTCOME MEASURES: Death or institutionalization after a minimum of 3 years' follow-up indicated poor prognosis, while the ability to live independently was regarded as a good prognosis for the purpose of survival (Kaplan-Meier) and discriminant function analysis. RESULTS: Patients with normal or borderline MRI findings (n = 15) showed significantly longer survival to institutionalization or death than those (n = 16) with definite frontotemporal atrophy (mean +/- SE, 9.3 +/- 1.7 years vs 3.0 +/- 0.7 years; P<.01). Using groups defined by 3-year outcome (good or bad prognosis), cerebral atrophy predicted poor outcome while age, symptom duration, cognitive performance, behavioral impairment, and overall disability at baseline did not. CONCLUSIONS: Patients with FTD with normal MRI results follow a more benign course than cases with atrophy at presentation. The substrate of the behavioral symptoms in such cases may differ from the neurodegenerative pathological features typically associated with FTD.