Differences in sleep disturbance according to mild cognitive impairment subtypes in the community

초록

Background: In normal aging and dementia, prevalence of sleep disorder is increased and both sleep continuity and architecture is altered. Almost study reported that sleep disturbance is most common neuropsychiatric symptom of mild cognitive impairment (MCI). However the nature of sleep in mild cognitive impairment is still unknown. Objective: We aimed to investigate the sleep disturbance of the community-dwelling elderly and compare them according to MCI subtypes, dementia and normal control. Methods: For the screening dementia, face-to-face household survey was conducted in five different regions of Korea from June 2008 to August 2008. There were 3,074 subjects, aged more than 65, and the response rate was 57.6 % (Number of respondents was 1770 people). Cognitive function was evaluated using the Korean version of the CERAD Neuropsychological Assessment Battery among elderly who had 1.5 standard deviation below the age-, sex- and year of education- specific mean of MMSE. Activities of daily living were evaluated using the Blessed Dementia Scale in the CERAD Clinical Assessment Battery (Korean version). The diagnosis of MCI was made using Petersen Criteria. Depression was excluded by using short form GDS because depression could affect of sleep quality and cognitive function. Cut off value of GDS was eight. The quality of sleep was measured by using eight items-questionnaires that included time in bed, total sleep time, difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, and nonrestorative sleep. The diagnosis of restless leg syndrome (RLS) was made using RLS questionnaire. Results: 1295 subjects were analyzed: 1120 were classified as normal aging group, 147 as MCI, and 28 as dementia. Among MCI group, 99 were classified as amnestic MCI and 48 were non-amnestic MCI. The mean age of MCI patients was older than normal group and younger than dementia patients (p<0.05). The dementia patients were less educated than normal group and MC