A multi-institutional study, led by researchers at the University of Miami Miller School of Medicine, found that visual impairment was associated with both insomnia and cognitive loss in Hispanic groups. The study, titled “The Effect of Self-Reported Visual Impairment and Sleep on Cognitive Decline: Results of the Hispanic Community Health Study/Study of Latinos,” was recently published in the Journal of Alzheimer’s Disease.
“We know that sleep disorders can lead to cognitive decline,” said Alberto Ramos, M.D., professor of clinical neurology and sleep medicine and senior author on the paper. “We also know that visual disturbances, independent of sleep problems, are associated with cognitive decline. We need to develop a more nuanced understanding of how these different factors are related.”
This multidisciplinary investigation included researchers from the University of Miami’s Bascom Palmer Eye Institute, as well as epidemiologists, neurologists and cognitive neuroscientists. The team investigated 665 participants in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a multi-center population investigation. Participants received an initial screening, during which they self-assessed their visual function and sleep and completed cognitive tests. They were reassessed seven years later.
“We saw that people who had more, or worsening, visual disturbances had worse insomnia,” said Dr. Ramos. “People who had more pronounced visual disturbances had worse cognitive problems as well, including declines in verbal fluency. This might be an early marker for cognitive problems in this population.”
Light and Circadian Rhythm Disruption
Visual impairment tends to cause sleep issues because light has a powerful impact on the body’s circadian rhythms, the 24-hour sleep/wake cycles that affect virtually every cell in the body. These systemic effects could have a profound impact on health.
Dr. Ramos and colleagues are particularly focused on how these disturbances might affect blood pressure. Normally, pressure is higher during the day and lower at night. However, sleep/circadian rhythm dysfunctions might alter this cycle, increasing nighttime blood pressure.
“We are concerned that blood pressure will remain high throughout the night and that might drive cardiovascular, cardiometabolic and vascular brain issues,” said Dr. Ramos. “We know that vascular brain problems can lead to cognitive decline.”
The authors hope this work will lead to better prevention efforts. At this moment, there are no therapies that can reverse Alzheimer’s and other forms of dementia. However, by better controlling risk factors, people may be able to delay or even avoid these conditions.
“We project that many more people will suffer from dementia by 2050,” said Dr. Ramos. “We want to better understand the factors that put people at risk and the steps they can take when they are middle aged or even younger to change their trajectories. People should think of sleep as a pillar of health, the same as nutrition and exercise.”