Researchers from the University of California have suggested an association between disrupted sleep and changes in cognitive function in midlife adults.
Alzheimer’s disease (AD) is a degenerative brain disorder that impacts memory, thinking abilities and essential cognitive functions. In the UK, the disease affects approximately 850,000 people.
“Previous studies suggest that how long we sleep each night can affect dementia risk,” said Dr Susan Mitchell, head of policy, Alzheimer’s Research UK.
She added: “Less is known about disrupted sleeping patterns, so this study gives us interesting insight into how this may be affecting cognitive function.”
Researchers examined the association between sleep duration and quality in 526 participants in their mid-30s to late 40s, as well as midlife cognition, which was assessed 11 years later among black and white adults.
Between 2003 and 2005, and over a decade after, participants had their sleeping patterns tracked using a device worn on the wrist and completed both thinking and memory tests, including a digit symbol substitution test to match symbols to numbers and a stroop test, which tests a person’s selective attention capacity, skills and processing speed.
Additionally, they also used a rey auditory verbal learning test, a Montreal cognitive assessment and letter fluency, and category fluency test to evaluate midlife cognition.
Researchers found that participants who had a higher level of disrupted sleep were twice as likely to perform worse in memory and thinking tests compared to those who had the least disrupted sleep.
However, researchers are yet to learn whether disrupted sleeping patterns are causing the decline in cognition or whether the decline in cognition is causing the disruptions in sleep.
Mitchell said: “Future studies looking at sleep disturbances in midlife and whether they are linked to dementia risk in later life are needed to get a clearer picture of cause and effect.
“Deeper insight into sleep and dementia could also be gained by studies looking at how levels of key AD proteins, such as amyloid or tau, are affected by sleep changes.”
