Insights into Biological Clock Assists Alzheimer’s Prevention

According to new Alzheimer’s research from UVA Health, increased light sensitivity may contribute to “sundowning”—the worsening of the disease’s symptoms late in the day—and cause sleep disruptions, which are thought to contribute to the disease’s progression. The researchers’ findings were reported in Frontiers in Aging Neuroscience. According to the researchers, the new insights into the abnormalities of the biological clock seen in Alzheimer’s could have significant implications for the development of medicines as well as symptom management. Caregivers sometimes battle with Alzheimer’s patients’ unpredictable sleep patterns caused by disturbed “circadian rhythms,” as the body’s natural daily cycle is defined. According to the latest research, light therapy could be a useful way to help manage this.

Understanding the effects of Alzheimer’s disease on the biological clock may potentially have implications for disease prevention. Poor adult sleep quality is a risk factor for Alzheimer’s disease because our brains naturally cleanse themselves of amyloid beta proteins that are hypothesized to develop detrimental tangles in Alzheimer’s.

“Circadian disruptions have been recognized in Alzheimer’s disease for a long time, but we’ve never had a very good understanding of what causes them,” said researcher Thaddeus Weigel, a graduate student working with Dr. Heather Ferris of the University of Virginia School of Medicine’s Division of Endocrinology and Metabolism. “This research points to changes in light sensitivity as a new, interesting possible explanation for some of those circadian symptoms.”

Alzheimer’s disease is the most common type of dementia, affecting 50 million people worldwide. Its defining feature is gradual memory loss, to the point where patients can forget their own loved ones, but it can also cause restlessness, anger, bad judgment, and incessant searching. These sensations frequently aggravate in the evening and at night.

Ferris and her colleagues used an Alzheimer’s mouse model to better understand what happens to the biological clock in the disease. They essentially gave the mice “jet lag” by varying their light exposure, then observed how it altered their behavior. Alzheimer’s mice behaved substantially differently from normal mice.

The Alzheimer’s mice, the researchers discovered, adapted to a six-hour time change substantially faster than the control mice. The experts believe this is due to a greater sensitivity to variations in light. While our biological clocks generally take signals from light, this shift takes time since the body requires time to adjust. This shift, however, occurred excessively quickly in Alzheimer’s mice.

The researchers initially suspected that this was due to inflammation in the brain, or “neuroinflammation.” So they investigated immune cells known as microglia, which have emerged as interesting targets in efforts to build improved Alzheimer’s treatments.

While targeting microglia may be advantageous for other reasons in Alzheimer’s treatment, the scientists eventually ruled out the notion, determining that microglia had no effect on how rapidly mice acclimated.

UVA researchers also ruled out “mutant tau,” an aberrant protein that produces tangles in the Alzheimer’s brain. The presence of these tangles had no effect on the mice’s adaptation.

The researchers’ findings do show that the retina plays a key part in the increased light sensitivity in Alzheimer’s disease, providing them with a viable route to investigate as they strive to create novel strategies to treat, manage, and prevent the disease.

“These data suggest that controlling the kind of light and the timing of the light could be key to reducing circadian disruptions in Alzheimer’s disease,” Ferris said. “We hope that this research will help us to develop light therapies that people can use to reduce the progression of Alzheimer’s disease.”

Source Link