[Neuropsychiatric features in Dementia with Lewy bodies and Alzheimer's disease].

BACKGROUND AND PURPOSE: Dementia with Lewy bodies (DLB) is commonly accompanied by neuropsychiatric symptoms. Among them, visual hallucinations are reportedly distinguishing DLB from Alzheimer's disease (AD). However, studies that compared frequency of delusions or depression between in DLB and in AD demonstrated conflicting results. Other neuropsychiatric symptoms including aggression, anxiety, and disinhibition have been rarely explored in DLB. In the present study, in order to elucidate the distinctive neuropsychiatric features in DLB, we analyzed neuropsychiatric symptoms in patients with DLB and with AD using data-based materials.

SUBJECTS AND METHODS: Subjects were 15 DLB patients extracted from the Dementia Data Bank in the Hyogo Institute for Aging Brain and Cognitive Disorders, where clinical information of patients with dementia were prospectively assembled with planed, standardized assessments. Both patients groups did not differ in age, education, and duration of illness. The male proportion was significantly greater in the DLB group compared with the AD group (DLB: Male 8, Female 7; AD: Male 27, Female 124, p = 0.008). Patients' neuropsychiatric symptoms were assessed with the Neuropsychiatric Inventory during an interview with a caregiver familiar to the patient's everyday behavior. The Mini-Mental State Examination (MMSE) was used for assessing severity of cognitive impairment.

RESULTS: The DLB group had significantly lower MMSE scores compared with AD group (DLB: 16.2 +/- 5.6, AD: 19.3 +/- 4.4, p = 0.013). None of neuropsychiatric symptoms, however, showed a significant relationship with MMSE scores in the DLB group. Hallucination were present in eight (53.3%) of the DLB group. Visual hallucinations were present in seven patients, and both visual and auditory hallucinations in one patient. The frequency of hallucinations (p < 0.0001) and that of visual hallucinations (p < 0.0001) were significantly greater in the DLB group than in the AD group. There was no significant difference in the frequency of auditory hallucinations. Delusions were present in 11 (73.3%) of the DLB group. Misidentification delusions were present in 11 patients, and persecutory delusions were coexisted in 8 patients. The frequency of delusions and that of persecutory delusions in the DLB group did not significantly differ from the AD group. However, the frequency of misidentification delusions was significantly greater in the DLB group than in the AD group (p < 0.0001). No significant difference was noted in the frequency of other neuropsychiatric symptoms.

CONCLUSIONS: Hallucinations, especially visual hallucinations, and misidentification delusions are helpful diagnostic features of DLB in differentiating from AD.