Sleep habits of dogs and humans with dementia have striking similarities - study

Researchers have found that dogs may have the same disruptive sleep patterns as humans when suffering from an Alzheimer's or dementia diagnosis.

An early indicator of Alzheimer's disease is a disruption in sleep patterns. Many sleep-related issues, from daytime sleepiness, staying awake longer, to waking up in the middle of the night, are believed to stem from damage to sleep-regulated areas of the brain. However, these patterns are not based solely on the human brain, but can also be identified in dogs. 

A new peer-reviewed study published in Frontiers in Veterinary Science has uncovered that the same reduction in sleep time and brain waves can occur in dogs with dementia, causing them to sleep less deeply.

“Our study is the first to evaluate the association between cognitive impairment and sleep using polysomnography – the same technique as used in sleep studies in people – in aged dogs,” Dr. Natasha Olby stated. Olby is a professor of veterinary neurology and neurosurgery at North Carolina State University and a senior author of the study.

Old dogs with or without the diagnosis

Dr. Olby and her team studied more than 25 senior mixed and full-breed dogs of both genders in the 10- to 16-year-old range. Owners were asked to answer questions about their pets and rate their symptoms based on severity. Were they getting disoriented, not socializing well, or having accidents inside? Dogs were also examined for orthopedic, neurological, biochemical, and physiological co-morbidities.

Of the dogs studied, only 8 were deemed normal. The rest had, at the very least, mild cases of canine cognitive dysfunction syndrome (CCDS). For as many as were deemed normal, there were the same amount deemed to have severe cases.

After a series of cognitive tests on the canine companions, which measured attention, memory, and control, including a task that required them to take a detour to grab a snack from a side that wasn't their typical place, these pups were able to exhibit their cognitive flexibility.

Examining sleep patterns in dogs

Dogs took a mid-afternoon snooze in a "sleep clinic" in which their brain waves were measured along with muscles, heart, and eye movements. These tests typically lasted multiple hours but were stopped if a dog was anxious or wanted to leave. Most dogs (93%) entered drowsiness, 86% entered NREM sleep and 54% entered REM sleep cycles.

These results revealed that the dogs with dementia had a harder time falling asleep and spent less time asleep in any cycle. Dogs with poor memory scores also indicated that they slept less deeply during the same tests.

The results showed that dogs with higher dementia scores, and dogs who did worse on the detour task, took longer to fall asleep and spent less time sleeping, and this was true for both NREM and REM sleep.

“In people, slow brain oscillations are characteristic of SWS and linked to the activity of the so-called ‘glymphatic system, a transport system that removes protein waste products from the cerebrospinal fluid,” said Olby. “The reduction in slow oscillations in people with Alzheimer’s, and the associated reduced removal of these toxins, has been implicated in their poorer memory consolidation during deep sleep.”