Can sleeping poorly lead to dementia? See what science says

Retired engineer José Ricardo, 60, and his father Márcio Rangel Alves, 86, have always been passionate about football. As one lived in São Paulo and the other in Rio de Janeiro, the two followed the games of their favorite team, Vasco da Gama, talking on the phone during matches. But five years ago, José noticed something different about his father.

“He would call me later and ask if Vasco had played. And I thought ‘dammit, but we saw this game and we’ve already talked about it'”, he says. This and other forgetting of everyday events led him to look for a geriatrician who confirmed through tests that Márcio had Alzheimer’s, the best known and most prevalent type of dementia.

Marked by the persistent decline of cognitive functions, such as memory, language, behavior and instrumental functions, dementias are neurodegenerative disorders that have a number of risk factors. “Inheritance, low education and illiteracy, obesity, hypertension, dyslipidemia and age”, lists psychiatrist Rita Cecília Reis Ferreira, from the Senior Citizens Program at the Institute of Psychiatry at Hospital das Clínicas (IPq-HC), in São Paulo.

But in addition to these, which are already well defined by science, another has been studied more in the last ten years: sleep.

Researchers from several European institutions examined data from 7,959 participants in another study, the Whitehall II, to understand the association between sleep duration and the incidence of dementia in older people. Over the 25 years in which the members were followed up, 521 cases of the syndrome were diagnosed.

The work, published in the scientific journal Nature in 2021, showed that individuals in their 50s, 60s and 70s who sleep for 6 hours or less daily have a 30% higher risk of developing dementia than those who sleep for 7 hours. This finding is valid regardless of sociodemographic, cardiometabolic, behavioral and mental health factors.

A more recent study, published in JAMA Neurology, conducted with 4,417 people with an average age of 71 years, concluded that sleeping less than 6 hours a day in old age is associated with cognitive decline, higher body mass index, depressive symptoms and greater burden. of β-amyloid — which, together with the tau particle, are the proteins whose accumulation in the glymphatic system, in the brain, is behind the onset of Alzheimer’s.

This relationship is explained by the very process that occurs when we sleep. Rita says that it is in the deepest phase of sleep that our memories are consolidated. “During this period, the glymphatic system does a kind of ‘cleaning’ in the brain, removing free radicals and substances that are no longer relevant and that in high amounts cause problems”, she reports.

Two of these substances are the so-called β-amyloid and tau proteins. “So, these substances tend to accumulate more, leading to the onset of dementia”, he concludes.

This was the case with Marcio. His son says his father was physically active, was always reading a book and had no Alzheimer’s in the family. “But my father slept very little. In addition to working a lot, he had a respiratory problem that prevented him from sleeping properly. 40 years old”, laments José.

However, the association between sleep and dementia is still a murky area in science. Although it is already known about the general damages of the lack of daily rest at any age (worsening quality of life, compromised attention, more difficult concentration), it is not known for sure how much investing in good sleep hygiene protects against the syndrome. .

In 2020, The Lancet, one of the most reputable scientific journals in the world, published the update of a 2017 report, which brings a series of risk factors for this type of disorder and actions to adhere to on a daily basis that tend to protect the brain. It turns out that sleeping well was not among the 12 measures listed in the document.

According to neurologist Luciano Talma Ferreira, from Hospital Universitário de Brasília (HUB-UnB), a potentially effective intervention to prevent dementia is based on the control of chronic diseases, educational stimulation and lifestyle changes.

“Research is needed to assess whether directing attention to sleep disorders may represent a new treatment opportunity or even a preventive strategy in Alzheimer’s disease”, says the doctor, who is also a member of the Brazilian Society of Neurology (SBN).

An investigation published in March 2022 by the University of California, United States, is an example of this effort. The group of scientists looked at so-called “elite sleepers,” which are people of all ages who sleep less than 6.5 hours a night but do not appear to suffer the cognitive effects of this habit due to genetic mutations.

As the number of individuals tracked is not enough for robust research, the group did a preliminary analysis with mice to better understand this phenomenon. It found that animals that carried the DEC2 and NPSR1 genes suffered a slower accumulation of β-amyloid and tau particles. According to scientists, the discovery could pave the way for the development of new drugs to treat dementia.

New studies must come out of the oven to reach clearer conclusions about the relationship between sleep and this sad health problem. Until then, it is worth paying attention to your rest hours. That’s what José has been doing since his father’s diagnosis.

“The hard part of this disease is that you are alive, but your identity doesn’t exist. It’s terrible. My father worked more than 70 years at this intensity. I retired soon because I don’t want to live like him”, he concludes.