Clinical, neuroimage, and neuropsychological profiles of semantic dementia

Abstract

Objective To explore the clinical, neuroimage, and neuropsychological profiles of semantic dementia (SD). Methods Detailed medical history were collected on 18 SD patients. Brain MRI scans were administered. Neuropsychological evaluation taping semantic memory (things naming), overall cognitive function (Mini-mental State Examination, MMSE), visuoconstructive skill (Clock Drawing Test, CDT), daily functional ability (Activities of Daily Living, ADL), neuropsychiatric symptoms (Neuropsychiatric Inventory, NPI), and disease severity (Frontotemporal Lobar Degeneration Modified Clinical Dementia Rating Scale, FTLD-CDR) were performed on all patients. Results The mean age at onset was （60.6±8.5） years, with 5 cases over 65. All patients developed progressive word-finding difficulty and anomic speech. Ten patients complained significant memory impairment and 14 experienced behavioral disturbance. Five patients were previously diagnosed as Alzheimer’s disease (AD) and 1 as schizophrenia. All patients developed marked semantic memory impairment both for living things and nonliving things. The mean score on MMSE was 10.94 ± 8.86, with 16 cases performed incorrectly on naming. Mean score on CDT copy was 4.61±0.85, with 14 cases scored normally. Mean score on ADL was 29.72±8.75. Cases with a 5-year course showed a significant overall decline. Fourteen cases presented behavior symptoms and scored 8.00±7.22 on NPI. All patients scored worst on language domain among all the domains evaluated in FTLD-CDR. Atrophy, typically involving the left anterior temporal was shown on MRI scans. However, predominantly right temporal atrophy was observed in one patient. Atrophy confined to the temporal lobe in patients with early stage and extended to the contralateral temporal, frontal lobe, and parietal lobe as disease progression. Conclusions Current study suggested that SD tend to develop in presenile age. However, about 1/3 cases develop the disease after 65 years. Deficit in language is the earliest and most prominent symptom. Behavior change is prevalent as well. Patients are commonly misdiagnosed as AD or lack a definite diagnosis. Visuoconstructive skill and other abilities are relatively preserved in the early stage. With progression into the 5th years, overall decline comes inevitably. Brain scans can reflect the disease characteristics and progression. Of note, there exists individual with right dominant atrophy. Key words: Dementia; Magnetic resonance imaging; Neuropsychological tests