Poor Sleep, Poor Brain Health: The Crucial Role for Sleep

Kahn Center for Cardiac Longevity Blog Poor Sleep, Poor Brain Health: The Crucial Role for Sleep
When I trained as a cardiologist in the 1980's, we were taught very little about the connection between sleep quality and overall health. In fact, the hours were so long and intense that I slept poorly for years due to job demans.  All of that has now changed and sleep may be the most important health habit to conquer. 
 
Despite so much of a new emphasis on sleep, there is much more to learn. The relationship between insomnia and cognitive decline is poorly understood.
 
A new study investigated associations between chronic insomnia, longitudinal cognitive outcomes, and brain health in older adults.  This study is important becauses estimates are that up to 20% of people experience insomnia.
 
Insomnia is a common sleep disorder characterized by persistent difficulty falling or staying asleep, despite having adequate time and opportunity to do so. It is defined by the following criteria: 
  • Difficulty initiating sleep (taking more than 30 minutes to fall asleep) 
     
  • Difficulty maintaining sleep (waking up frequently during the night) 
     
  • Early morning awakening (waking up too early and being unable to fall back asleep) 
     
  • Non-restorative sleep (feeling tired or unrefreshed during the day) 

STUDY METHODS

From the population-based Mayo Clinic Study of Aging, the authors identified cognitively unimpaired older adults with or without a diagnosis of chronic insomnia who underwent annual neuropsychological assessments (z-scored global cognitive scores and cognitive status) and had quantified serial imaging outcomes (amyloid-PET burden [centiloid] and white matter hyperintensities from MRI [WMH, % of intracranial volume]).
 

STUDY RESULTS

The study included 2,750 participants (mean 70 years old, 49% female) in global cognition models and 2,814 in Cox models with median follow-up of 5.6 years.
 
Insomnia was associated with a 0.011 per year faster decline in global cognitive scores and 40% increased risk of CI (hazard ratio.
Insomnia with reduced sleep was associated with baseline cognitive performance, WMH, and amyloid-PET burden.
Insomnia participants sleeping more than usual (potentially indicating remission of symptoms) had lower baseline WMH burden.

STUDY DISCUSSION

This important study found an association between insomnia, cognitive decline, and increased risk for CI.
 
At the study’s conclusion, researchers discovered that participants with chronic insomnia had a 40% higher chance of developing dementia or MCI than participants with non-chronic insomnia, which is reportedly equivalent to 3.5 additional years of aging.
 
Additionally, researchers found that study participants who slept less than usual were more likely to have an increased amount of white matter hyperintensities and amyloid plaques in their brains.

One of the authors commented that : "In our models, the impact of insomnia in the risk of MCI/dementia was higher than having two cardiometabolic conditions like hypertension and diabetes, or being 3.5 years older than your actual age, which are known risk factors. This (is) a significant finding because (it will) bring insomnia to the spotlight of potential modifiable risk factors. The size of this association is significant from a public health perspective, particularly for a disorder that is so prevalent in older adults”.
 
Insomnia with reduced sleep was associated with worse cognitive performance and poorer brain health (WMH and amyloid burden) at baseline.
 
This was not a randomized study and no therapy was tested. Therefore, it highlights the importance of avoiding insomnia for brain health but future studies will need to test various strategies to optimize sleep and brain health.
 
At the Kahn Center, we routinely perform sleep studes and refer patients for dental or CPAP therapies for obstructive sleep apnea.
We also teach natural approaches to better sleep including natural supplements like low-dose plant-based melatonin. 
 
 
Author
Dr. Joel Kahn

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