Sleep quality and cognitive decline in a community of older adults in Daqing City, China.

OBJECTIVES: To examine the association between self-reported sleep quality and cognitive decline one year later. PATIENTS/METHODS: A longitudinal study of 1010 cognitively intact adults, aged 65-80 years at baseline, from two urban communities in China was performed. Sleep quality at baseline was measured using the Pittsburgh Sleep Quality Index (PSQI). Cognitive function was determined by using the Chinese version of Mini-Mental State Examination (CMMSE) at the baseline and one year later. Substantial CMMSE decline was defined as the CMMSE score decreases by three or more points during the follow-up. Potential confounders, such as age, sex, education, baseline CMMSE score, depression, physical activity level, drinking status, smoking status, body mass index, snoring frequency, history of hypertension, diabetes, and coronary heart disease were measured via questionnaires or physical examination. RESULTS: After adjusting for potential confounders, individuals with poor sleep quality (PSQI > 7), relative to whose with good sleep quality, had 0.32 (95% CI: -0.62, -0.02; p = 0.04) CMMSE-points more decline and tended to have a higher likelihood of developing substantial CMMSE decline (OR = 1.46; 95% CI: 0.97, 2.18; p = 0.06). Among seven subscales of the PSQI, poor sleep efficiency was associated with greater CMMSE decline (beta = -0.16, 95% CI: -0.29, -0.03; p = 0.01) and higher risk of substantial CMMSE decline (OR = 1.24, 95% CI: 1.05, 1.46; p = 0.01). Short sleep duration (sleeping ≤5 h/night) was also significantly associated with more CMMSE decline and a higher likelihood of developing substantial CMMSE decline (p <0.05 for both). CONCLUSIONS: Self-reported poor sleep quality may be an indicator of early cognitive decline for elderly people and should be paid particular attention by clinicians.

Association between Sleep Duration, Insomnia Symptoms and Bone Mineral Density in Older Boston Puerto Rican Adults.

OBJECTIVE: To examine the association between sleep patterns (sleep duration and insomnia symptoms) and total and regional bone mineral density (BMD) among older Boston Puerto Rican adults. MATERIALS/METHODS: We conducted a cross-sectional study including 750 Puerto Rican adults, aged 47-79 y living in Massachusetts. BMD at 3 hip sites and the lumbar spine were measured using dual-energy X-ray absorptiometry. Sleep duration (≤5 h, 6 h, 7 h, 8 h, or ≥9 h/d) and insomnia symptoms (difficulty initiating sleep, difficulty maintaining sleep, early-morning awaking, and non-restorative sleep) were assessed by a questionnaire. Multivariable regression was used to examine sex-specific associations between sleep duration, insomnia symptoms and BMD adjusting for standard confounders and covariates. RESULTS: Men who slept ≥9h/d had significantly lower femoral neck BMD, relative to those reporting 8 h/d sleep, after adjusting for age, education level, smoking, physical activity, depressive symptomatology, comorbidity and serum vitamin D concentration. This association was attenuated and lost significance after further adjustment for urinary cortisol and serum inflammation biomarkers. In contrast, the association between sleep duration and BMD was not significant in women. Further, we did not find any significant associations between insomnia symptoms and BMD in men or women. CONCLUSIONS: Our study does not support the hypothesis that shorter sleep duration and insomnia symptoms are associated with lower BMD levels in older adults. However, our results should be interpreted with caution. Future studies with larger sample size, objective assessment of sleep pattern, and prospective design are needed before a conclusion regarding sleep and BMD can be reached.