Dementia affects at least 55 million people worldwide and the number is increasing by about 10 million every year. In part, this is because we are living longer, but dementia is not an inevitable part of aging. So, are there ways to decrease our risk of developing dementia? Much research is currently focusing on the potential role of sleep.
According to the World Health Organization (WHO), “dementia is currently the seventh leading cause of death among all diseases and one of the major causes of disability and dependency among older people globally.” The WHO states that around 55 million people have dementia, and by 2050 the number is likely to be almost 140 million. Between 60% and 70% of people with dementia have Alzheimer’s disease. Dementia is primarily a disease of old age, although young-onset dementia — where symptoms begin before the age of 65 — accounts for about 9% of cases. However, dementia is not an inevitable consequence of aging. There is a genetic component to dementia — if you have a close relative with dementia, this might increase your risk. However, several studies have shown that even those with a hereditary risk can reduce it by adopting a healthy diet, exercising regularly, and avoiding smoking and too much alcohol.
Sleep apnea affects almost 1 billion people worldwide, the most common form being obstructive sleep apnea (OSA). The condition interrupts breathing during sleep and often wakes a person up. Recent studies have also suggested links between sleep apnea and dementia. This hypoxia is thought to cause brain changes. One study found that the temporal lobes — which are vital for memory — were reduced in thickness in those with sleep apnea, a change that is also seen in people with dementia. Another study found that the hippocampus was reduced in volume in people with sleep apnea — hippocampal atrophy is a feature of Alzheimer’s disease. This study also showed that two toxins — tau and beta-amyloid, which are thought to be responsible for many of the symptoms of dementia — build up in the brains of people with sleep apnea, probably because of a lack of oxygen in the blood. The same study suggested that improving sleep might be a way of alleviating dementia symptoms, but is it possible that treating sleep disorders might help prevent dementia? A 2019 review of studies into sleep disorders and cognitive decline tried to answer this question. It found that sleep disorders, including sleep apnea, insomnia, inadequate or overlong sleep, and sleep disturbance were linked to cognitive decline and dementia. There was also a link between sleep disorders and beta-amyloid and tau deposition. The review concluded that sleep management might be a promising target for dementia prevention.
However, no study has yet proved a causative link — or which way the relationship acted. Did sleep problems predispose to dementia, or were sleep problems a sign of the early stages of dementia?
References: https://www.medicalnewstoday.com/articles/dementia-and-sleep-what-do-we-know-about-this-link
