The role sleep plays in normal human brain physiology is becoming more clear as the link between abnormal sleep and dementia gets stronger. Here is yet another epidemiological study linking reduced sleep in middle age to a higher risk of dementia.
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Is the association between reduced sleep and dementia causal or is it due to reverse causation?
Sleep is required to consolidate memories and to allow the brain to cleanse itself, i.e. flush out all the intracellular debris that could aggregate to cause Alzheimer’s disease. Therefore, sleep deprivation by impairing memory consolidation and not allowing you to clear the brain's intracellular debris properly could lower your threshold for developing dementia in the future.
Reverse causation states that people who are destined to develop dementia have pathology that starts decades before dementia manifests, for example, amyloid deposition and neurofibrillary tangles. The pathology affects parts of the brain that cause you to have disrupted and less sleep. In other words, insomnia or disrupted sleep is part of the dementia prodrome.
Personally, I buy into the former hypothesis that poor sleep interferes with the normal functioning of the brain that puts one at increased risk of dementia in the future. This, would, therefore, make poor sleep a modifiable risk factor in our fight to reduce the burden of dementia on society. This is why I think we need a public health campaign to improve the sleep patterns across society and to encourage self-monitoring and screening for sleep disorders so that we can diagnose and manage sleep disorders early with the ultimate goal of preventing dementia.
Are you ready to make an effort and improve your sleep duration and quality? You will be surprised by how much this will affect your quality of life.
Séverine Sabia et al. Association of sleep duration in middle and old age with incidence of dementia. Nat Commun. 2021 Apr 20;12(1):2289. doi: 10.1038/s41467-021-22354-2.
Sleep dysregulation is a feature of dementia but it remains unclear whether sleep duration prior to old age is associated with dementia incidence. Using data from 7959 participants of the Whitehall II study, we examined the association between sleep duration and incidence of dementia (521 diagnosed cases) using a 25-year follow-up. Here we report higher dementia risk associated with a sleep duration of six hours or less at age 50 and 60, compared with a normal (7 h) sleep duration, although this was imprecisely estimated for sleep duration at age 70 (hazard ratios (HR) 1.22 (95% confidence interval 1.01-1.48), 1.37 (1.10-1.72), and 1.24 (0.98-1.57), respectively). Persistent short sleep duration at age 50, 60, and 70 compared to persistent normal sleep duration was also associated with a 30% increased dementia risk independently of sociodemographic, behavioural, cardiometabolic, and mental health factors. These findings suggest that short sleep duration in midlife is associated with an increased risk of late-onset dementia.
Conflicts of Interest
MS Research
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Medium
Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not reflect the position of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust.
Sleep is required to consolidate memories and to allow the brain to cleanse itself, i.e. flush out all the intracellular debris that could aggregate to cause Alzheimer’s disease. Therefore, sleep deprivation by impairing memory consolidation and not allowing you to clear the brain's intracellular debris properly could lower your threshold for developing dementia in the future.
Reverse causation states that people who are destined to develop dementia have pathology that starts decades before dementia manifests, for example, amyloid deposition and neurofibrillary tangles. The pathology affects parts of the brain that cause you to have disrupted and less sleep. In other words, insomnia or disrupted sleep is part of the dementia prodrome.
Personally, I buy into the former hypothesis that poor sleep interferes with the normal functioning of the brain that puts one at increased risk of dementia in the future. This, would, therefore, make poor sleep a modifiable risk factor in our fight to reduce the burden of dementia on society. This is why I think we need a public health campaign to improve the sleep patterns across society and to encourage self-monitoring and screening for sleep disorders so that we can diagnose and manage sleep disorders early with the ultimate goal of preventing dementia.
Are you ready to make an effort and improve your sleep duration and quality? You will be surprised by how much this will affect your quality of life.
Séverine Sabia et al. Association of sleep duration in middle and old age with incidence of dementia. Nat Commun. 2021 Apr 20;12(1):2289. doi: 10.1038/s41467-021-22354-2.
Sleep dysregulation is a feature of dementia but it remains unclear whether sleep duration prior to old age is associated with dementia incidence. Using data from 7959 participants of the Whitehall II study, we examined the association between sleep duration and incidence of dementia (521 diagnosed cases) using a 25-year follow-up. Here we report higher dementia risk associated with a sleep duration of six hours or less at age 50 and 60, compared with a normal (7 h) sleep duration, although this was imprecisely estimated for sleep duration at age 70 (hazard ratios (HR) 1.22 (95% confidence interval 1.01-1.48), 1.37 (1.10-1.72), and 1.24 (0.98-1.57), respectively). Persistent short sleep duration at age 50, 60, and 70 compared to persistent normal sleep duration was also associated with a 30% increased dementia risk independently of sociodemographic, behavioural, cardiometabolic, and mental health factors. These findings suggest that short sleep duration in midlife is associated with an increased risk of late-onset dementia.
Conflicts of Interest
MS Research
Medium
Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not reflect the position of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust.
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