Sleep disorders associated with higher risk of dementia, study finds

A new meta-analysis has found that individuals with sleep disorders face an increased risk of developing dementia. Specifically, those with obstructive sleep apnea had a 45% higher risk of Alzheimer’s disease, while individuals with insomnia had a 59% increased risk of vascular dementia and a 49% higher risk of Alzheimer’s disease compared to people without these sleep disorders. The research was published in GeroScience.

Sleep disorders are conditions that disrupt the quality, timing, or duration of sleep, affecting a person’s ability to function during the day. Common types include insomnia, sleep apnea, restless legs syndrome, and narcolepsy.

Insomnia involves difficulty falling or staying asleep, while sleep apnea is characterized by repeated interruptions in breathing during sleep. Restless legs syndrome causes uncomfortable sensations in the legs and a strong urge to move them, often disrupting sleep. Narcolepsy is a neurological disorder that leads to sudden episodes of sleep during the day.

Sleep disorders can be caused by stress, medical conditions, lifestyle factors, or mental health issues. Chronic sleep problems are linked to fatigue, mood disturbances, memory impairments, and a higher risk for conditions such as hypertension and depression.

Study author Zoltan Ungvari and his colleagues set out to investigate whether sleep disorders are associated with an increased risk of dementia. They were particularly interested in exploring the links between sleep disturbances and the risk of developing vascular dementia or Alzheimer’s disease—the two most common types of dementia.

Vascular dementia is a form of cognitive decline caused by reduced blood flow to the brain, often as a result of strokes or other vascular conditions. It can lead to problems with memory, thinking, and reasoning. Alzheimer’s disease is a progressive neurodegenerative disorder characterized by the accumulation of amyloid plaques and tau tangles in the brain. It leads to progressive memory loss, cognitive impairment, and behavioral changes.

To conduct their analysis, the researchers performed a meta-analysis of previously published studies. They searched for research examining the associations between various sleep disorders—such as obstructive sleep apnea, insomnia, excessive daytime sleepiness, sleep-related movement disorders, and circadian rhythm sleep disorders—and the diagnosis of dementia.

Their search yielded 12,684 records from three major scientific databases: PubMed, Cochrane Central, and Web of Science. After removing duplicates and irrelevant studies, they included 60 studies that examined the relationships between sleep disorders and all-cause dementia, Alzheimer’s disease, vascular dementia, or cognitive decline.

The results revealed that individuals with obstructive sleep apnea had a 33% higher risk of all-cause dementia compared to those without the condition. Insomnia was associated with a 36% increased risk, and other sleep disorders showed a 33% increase in risk.

When focusing on specific types of dementia, the analysis found that obstructive sleep apnea was linked to a 45% higher risk of Alzheimer’s disease. Insomnia was associated with a 59% increased risk of vascular dementia and a 49% higher risk of Alzheimer’s disease.

“This meta-analysis highlights the critical role of sleep disorders in dementia risk, emphasizing the need for early detection and management of sleep disturbances. Targeted interventions could play a pivotal role in reducing dementia risk, particularly among high-risk populations,” the study authors concluded.

The study sheds light on the links between sleep disorders and dementia. However, study authors note that many of the analyzed studies were based on self-reports, leaving room for reporting bias to affect the results.

The paper, “Sleep disorders increase the risk of dementia, Alzheimer’s disease, and cognitive decline: a meta‑analysis,” was authored by Zoltan Ungvari, Mónika Fekete, Andrea Lehoczki, Gyöngyi Munkácsy, János Tibor Fekete, Virág Zábó, György Purebl, Péter Varga, Anna Ungvari, and Balázs Győrfy.