Initial Symptoms in Frontotemporal Dementia and Semantic Dementia Compared with Alzheimer’s Disease

Background: Despite many reports about cognitive decline and behavioral changes in patients with frontotemporal lobar degeneration (FTLD), there have been very few systematic studies of initial symptoms of frontotemporal dementia (FTD) and semantic dementia (SD). Objective: It was the aim of this study to investigate FTD and SD and to establish whether they are characterized by different initial symptoms. Methods: Three groups of patients were studied: FTD (n = 36), SD (n = 17) and age-matched Alzheimer’s disease (AD) patients (n = 52). Information on initial symptoms was obtained from caregivers. Symptoms were classified into 22 distinct categories from the following domains, based on previous studies of symptoms of FTLD: (1) change in social behavior, affection, and daily activities, (2) cognitive decline, (3) language impairments, and (4) other abnormal symptoms. Results: Change in social behavior, affection, and daily activities was significantly more common in patients with FTD; on the other hand, language impairments were significantly more common in patients with SD as initial symptoms. Apathy and stereotypic behaviors were the most common initial symptoms among patients with FTD, while anomia, paraphasia, and impairment in word comprehension were the most common initial symptoms among patients with SD. Memory disturbance was the most common initial symptom among patients with AD. Conclusions: Behavioral and psychiatric symptoms are predominant initial symptoms in FTD, while language symptoms are predominant initial symptoms in SD. In addition to the assessment of current symptoms, the assessment of initial symptoms is useful for differential diagnosis in patients with FTD, SD and AD.