Everyone’s internal clocks are governed by “circadian rhythms,” a gene-based master clock that synchronizes the various body processes, including sleep and wake cycles, cognition and metabolism. It’s no secret that circadian rhythms change as people age, but new research suggests that one biological clock doesn’t start ticking until older age.
The study, published online in the Proceedings of the National Academy of Science, built on previous research showing a connection between circadian rhythms and aging. Researchers at the University of Pittsburgh School of Medicine (UPMC) and the Centre for Addiction and Mental Health (SAMH) studied 146 donated brain samples and discovered more than 200 genes involved in regulating the timing of the prefrontal cortex alone, the area of the brain responsible for cognition, including memory and learning.
"Studies have reported that older adults tend to perform complex cognitive tasks better in the morning and get worse through the day," said Colleen McClung, PhD, associate professor of psychiatry at UPMC, said in a release. "We know also that the circadian rhythm changes with aging, leading to awakening earlier in the morning, fewer hours of sleep and less robust body temperature rhythms."
Although most of the time-keeper genes waned with age, researchers discovered a set of genes that actually increases its rhythmic ability in brains of people older than 60.
The discovery could help science better understand sleep problems and cognitive shifts linked to circadian rhythms and may even help researchers develop a treatment for “sundowning,” a condition where older people grown anxious and agitated in the late afternoon.
"Since depression is associated with accelerated molecular aging, and with disruptions in daily routines, these results also may shed light on molecular changes occurring in adults with depression," said Etienne Sibille, PhD, chair in clinical neuroscience at SAMH, in a Medical News Today article.