Chronic insomnia disorder, which affects approximately 10 percent of adults, has a direct negative impact on the cognitive function of people 45 and over, according to a new study.
Chronic insomnia, one of the most common sleep disorders, is characterized by trouble falling asleep or staying asleep at least three nights a week for over three months with an impact on daytime functioning, such as mood, attention and daytime concentration.
“A number of studies have shown links between insomnia and cognitive problems,” said Dr. Thanh Dang-Vu, an associate professor at Concordia University and the university’s research chair in sleep, neuroimaging and cognitive health and a clinical associate professor in the Department of Neuroscience at Université de Montréal.
“However, many of these studies were conducted on a limited number of individuals suffering from insomnia, and the results are not always consistent from study to study.”
“Other studies do not distinguish between chronic insomnia disorder and the simple presence of symptoms,” he continued. “Chronic insomnia is often associated with other health issues, such as anxiety or chronic pain, that can also affect cognitive function, which makes it difficult to determine the direct contribution of insomnia to these cognitive problems.”
According to Dang-Vu, the purpose of the study was to determine the precise link between chronic insomnia and cognitive function, while also accounting for the possible effect of other health issues.
The analysis examined data from 28,485 participants aged 45 from Canada. Each participant belonged to one of three groups:
- people with chronic insomnia disorder;
- people with symptoms of insomnia who did not complain of any impact on their daytime functioning, and;
- people with normal sleep quality.
They all filled out questionnaires and underwent physical exams and a battery of neuropsychological tests to evaluate different cognitive functions and the quality of their sleep, the researcher explained.
“The individuals in the chronic insomnia group performed significantly worse on the tests compared to those from the other two groups,” he reported. “The main type of memory affected was declarative memory — the memory of items and events. This was the case even after accounting for other factors, be they clinical, demographic or lifestyle characteristics, which may influence cognitive performance.”
Further research will aim to better characterize this relationship between poor sleep and cognitive problems, he noted.
“Does chronic insomnia predispose people to cognitive decline? Can these cognitive deficits be reversed with sleep disorder treatment? There are many important questions that remain to be explored and that will have a major impact on the prevention and treatment of age-related cognitive disorders,” he concluded.
Source: Concordia University