A lifestyle with too little sleep is likely to lead to dementia, neuroscientists at Columbia University write in Dementia and Geriatric Cognitive Disorders Extra. The researchers discovered that of all over 65s who have a chronic lack of sleep, almost half are likely to develop dementia within a few years.
The researchers studied 1041 over 65s who did not have dementia. Just before the study started the researchers asked the participants whether they were getting enough sleep and whether they felt rested during the day. After that the researchers followed the participants for three years.
At the end of the three years, 78 participants [7.2 percent] had been diagnosed as having dementia. The participants with sleep problems in particular developed dementia. The chance of participants in this group developing dementia was 1.2 times higher than those who had no sleep problems.
You could argue that a 20 percent higher chance is nothing to get excited about. But the chance of developing dementia was much higher among the participants with serious sleep problems, as you can see in the figure below. Of the participants who said that none of the time did they get enough sleep, almost forty percent developed dementia.
The correlation between sleepiness during the daytime and dementia was even stronger than the correlation between too little sleep and dementia. About half of the participants who said they were sleepy “all the time” during the day developed dementia during the course of the study.
“Our study suggests that sleep inadequacy and increased daytime sleepiness are risk factors for dementia, […] in the elderly population, independent of demographics, clinical factors, and depression”, the researchers wrote. “Our findings may have significant public health implications and expand upon previous findings.”
“However, further investigation is needed in order to replicate these findings and further examine the possible biological mechanisms underlying the observed associations. Investigation of such mechanisms could allow future interventional studies to provide us with more convincing evidence for the importance of good sleep quality in relation to the risk of dementia.”
Daytime Sleepiness and Sleep Inadequacy as Risk Factors for Dementia.
To examine the association between self-reported sleep problems and incidence of dementia in community-dwelling elderly people.
1,041 nondemented participants over 65 years old were examined longitudinally. Sleep problems were estimated using the RAND Medical Outcomes Study Sleep Scale examining sleep disturbance, snoring, sleep short of breath or with a headache, sleep adequacy, and sleep somnolence. Cox regression analysis was used to examine the association between sleep problems and risk for incident dementia. Age, gender, education, ethnicity, APOE-?4, stroke, heart disease, hypertension, diabetes, and depression were included as covariates.
Over 3 years of follow-up, 966 (92.8%) participants remained nondemented, while 78 (7.2%) developed dementia. In unadjusted models, sleep inadequacy (‘Get the amount of sleep you need’) at the initial visit was associated with increased risk of incident dementia (HR = 1.20; 95% CI 1.02-1.42; p = 0.027). Adjusting for all the covariates, increased risk of incident dementia was still associated with sleep inadequacy (HR = 1.20; 95% CI 1.01-1.42; p = 0.040), as well as with increased daytime sleepiness (‘Have trouble staying awake during the day’) (HR = 1.24; 95% CI 1.00-1.54; p = 0.047).
Our results suggest that sleep inadequacy and increased daytime sleepiness are risk factors for dementia in older adults, independent of demographic and clinical factors.
PMID: 26273244 PMCID: PMC4521063 DOI: 10.1159/000431311 [PubMed]