Sleep characteristics and risk of dementia and Alzheimer's disease: The Atherosclerosis Risk in Communities Study.

INTRODUCTION: This study tested the hypotheses that late-midlife obstructive sleep apnea (OSA) and short and long sleep duration are associated with dementia over 15 years of follow-up.

METHODS: A total of 1667 Atherosclerosis Risk in Communities Study participants underwent in-home polysomnography (1996-1998) and were followed for dementia. Dementia was defined by (1) hospitalization diagnosis codes (1996-2012) and (2) a comprehensive neurocognitive examination (2011-2013) with adjudication.

RESULTS: OSA and sleep duration were not associated with risk of incident dementia. When using adjudicated outcomes, severe OSA (≥30 vs. <5 apnea-hypopnea events/hour) was associated with higher risk of all-cause dementia (risk ratio [95% confidence interval], 2.35 [1.06-5.18]) and Alzheimer's disease dementia (1.66 [1.03-2.68]); associations were attenuated with cardiovascular risk factor adjustment. Sleeping <7 versus 8 to ≤9 hours was associated with higher risk of all-cause dementia (2.00 [1.03-3.86]).

DISCUSSION: When adjudicated outcome definitions were used, late-midlife OSA and short sleep duration were associated with all-cause and Alzheimer's disease dementia in later life.