[REM sleep behavior disorder (RBD) in dementia with lewy bodies (DLB)--a study using short sleep-disorder questionnaire for DLB (SDQ-DLB)].

OBJECTIVE: To assess the validity of the short sleep-disorder questionnaire for dementia with Lewy bodies (SDQ-DLB). SDQ-DLB is a newly developed structured interview containing 10 items for assessing REM sleep behavior disorder (RBD) in DLB. SUBJECTS: The subjects were 23 patients with a clinical diagnosis of Alzheimer's disease (AD), 21 patients with possible DLB, and 7 patients with probable DLB. METHODS: SDQ-DLB was administered to reliable informants representing each patient. The frequency of positive endorsement for each item was compared between the 3 patient groups. RESULTS: The following 3 items of the questionnaire significantly differentiated between the patient groups: item 1 (Has the patient ever acted or talked in his/her nocturnal sleep while he/she seems to be half asleeps?), item 5 (Has the patient ever sat or got up on the bed (or the futon mattress) in his/her nocturnal sleep?) and item 6 (Has the patient ever gone out of the bed (or the futon mattress) to ambulate or to act violently in his/her nocturnal sleep while he/she seems to be half asleep?). The 7-point composite score of items 1 to 7 with 2 to 3 cut-off points showed 71% sensitivity in the patients with probable DLB, 51%sensitivity in the patients with possible DLB, and 91% specificity in the AD patients. CONCLUSION: The composite score of the 7 items of SDQ-DLB could distinguish AD from DLB with sufficient sensitivity and specificity. SDQ-DLB may be useful to evaluate RBD in DLB.