Very early semantic dementia with progressive temporal lobe atrophy: an 8-year longitudinal study.

BACKGROUND Semantic dementia is a syndrome within the spectrum of frontotemporal lobar degenerations characterized by fluent progressive aphasia (particularly anomia) and loss of word meaning. OBJECTIVE To report a unique case of very early semantic dementia with a slowly progressive course, allowing insights into the early natural history of this disorder. DESIGN Case report. SETTING A tertiary care center. PATIENT A 62-year-old woman who presented with "memory loss" complaints. MAIN OUTCOME MEASURES Clinical course, neuropsychological data, and magnetic resonance imaging results. RESULTS The patient was first evaluated when the results of standard neuropsychological measures were normal but subtle left anterior temporal lobe atrophy was present. During the follow-up period of 8 years, she developed profound anomia and loss of word meaning associated with progressive left anterior temporal lobe atrophy, consistent with semantic dementia. In more recent years, anterograde memory impairment and mild prosopagnosia evolved in association with left hippocampal atrophy and subtle atrophy in the homologous gyri of the right anterior temporal lobe. She remains functionally independent despite her current deficits. CONCLUSIONS Early identification of patients who will develop semantic dementia is difficult and might be missed with standard clinical, neuropsychological, and structural neuroimaging evaluations. Recognition of this relatively rare syndrome is important for early diagnosis and prognostication and particularly for therapeutic interventions in the future.