Sundowning in Alzheimer's: What might cause it and how to treat it

Evan Walker
Evan Walker TheMediTary.Com |
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Research in mice suggests that sundowning in Alzheimer’s may be caused by increased light sensitivity. Image credit: Tara Moore/Getty Images.
  • Sundowning in Alzheimer’s disease patients is a symptom that occurs in the late afternoon and evening.
  • It is characterized by increased confusion, agitation, anxiety, and mood swings.
  • The causes are little understood, and it has been assumed to be due to the effect of Alzheimer’s disease on the brain.
  • Recent research in mouse models of Alzheimer’s disease showed increased light sensitivity due to changes in the retina.

Sundowning is a debilitating symptom of Alzheimer’s disease that causes individuals to experience worsening dementia symptoms in the late afternoon and evening.

Some researchers have assumed this symptom was due to changes in the brain, and indeed, recently a study showed that circadian disruptions in the immune cells in the brains of Alzheimer’s patients could worsen the buildup of amyloid beta in the brain.

The buildup of this protein is one of the defining characteristics of Alzheimer’s disease.

Dr. Alexander Lapa, a psychiatrist from the Rehab Clinics Group told Medical News Today in an email:

“Sundowning can be distressing for both the affected individual and their caregivers. The increase in confusion and agitation can lead to increased care needs and may cause significant disruption to daily routines. In some cases, sundowning may even compromise the safety of the patient or others around them.”

He added that many physicians suggest patients with Alzheimer’s disease stick to a daily routine with consistent timings, calming activities, minimizing noise, and ensuring adequate lighting in the evening.

Despite the debilitating nature of this symptom of Alzheimer’s disease, the cause of sundowning is not known. The fact that it occurs in the mid- and later stages of Alzheimer’s disease means that it may occur alongside a number of other symptoms, such as disturbed sleep or forgetting to eat and drink, or side effects of certain drugs, all of which have been linked to sundowning.

As sleep disturbance has been strongly associated with Alzheimer’s disease in the past, a team of researchers from the University of Virginia, Charlottesville, VA, decided to investigate this link more thoroughly. Their findings recently appeared in Frontiers to Aging Neuroscience.

It had been assumed that disruption to the brain caused by the accumulation of amyloid beta protein, and tau protein, both hallmarks of Alzheimer’s disease, could also cause sleep disturbance.

“We were interested in why sleep and circadian rhythms are disrupted in Alzheimer’s disease,” lead author Dr. Heather Ferris, assistant professor of medicine at the University of Virginia, told MNT.

“We actually thought the brain would be where the problem was occurring, but after ruling out several causes in the brain we turned our attention to the retina,“ she said.

“The retina has specialized cells called intrinsically photosensitive retinal ganglion cells,“ Dr. Ferris explained. “These are light-sensitive cells, but they are not used for vision. Rather, these cells are used to tell the brain that it is daytime.“

“We found that in [Alzheimer’s disease model] mice we could trigger these cells with much less light and that there were more of these cells in the retina,” she told MNT.

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