By Cara Murez
HealthDay Reporter
MONDAY, May 1, 2023 (HealthDay News) — Like people, man’s best friend can develop dementia with age.
And these older dogs sleep less soundly when they develop the condition, just as people with Alzheimer’s disease do, according to research that included problem-solving tasks and brain wave measurements.
“Our study is the first to assess the association between cognitive decline and sleep using polysomnography, the same technique used in human sleep studies, in elderly dogs,” said study lead author Dr. Natasha Olby, professor of veterinary neurology. and neurosurgery at North Carolina State University.
The first symptoms of Alzheimer’s disease in people usually involve interruptions in sleep rhythms. This may be due to damage to areas of the brain that regulate sleep.
Alzheimer’s patients show the greatest reduction in slow wave sleep (SWS), which is a stage of dreamless sleep with slow “delta” brain waves. Daytime memories are consolidated during this phase.
These patients also spend less time in both REM (rapid eye movement) sleep, in which most dreams occur, and non-REM (NREM) sleep.
The scientists in this study found the same reduction in sleep time and delta brain waves in dogs with canine cognitive dysfunction syndrome (CCDS), or the canine equivalent of dementia.
In the study, published April 28 in the journal frontiers in veterinary science, The researchers evaluated 28 mixed and purebred senior male and female dogs ranging in age from 10.4 to 16.2 years. This is around 81% to 106% of their average lifespan, depending on size.
Dog owners answered questions about their pets, including rating the severity of CCDS symptoms such as disorientation, poor social interactions, and soiling in the house.
The researchers also looked for orthopedic, neurological, biochemical, and physiological conditions in the dogs.
Eight dogs were classified as normal. Eight others had mild CCDS. Four more had moderate CCDS and eight had severe disease.
The researchers tested the dogs’ attention, working memory and executive control with a variety of tasks.
In the “diversion task”, a dog needed to retrieve its treat from a horizontal transparent cylinder by accessing it from either end. The researchers then made the task more challenging by blocking out the dog’s preferred side. They would need to show the cognitive flexibility to veer to the other extreme.
In a canine “sleep clinic,” dogs were allowed to nap spontaneously in a quiet, dark space with white noise while researchers conducted polysomnography studies.
The electrodes measured their brain waves, the electrical activity of the muscles and heart, and the dogs’ eye movements for up to two hours. About 93% of the dogs fell asleep, 86% entered NREM sleep, and 54% entered REM sleep.
Dogs with higher dementia scores, and dogs that did worse on the diverting task, took longer to fall asleep and spent less time sleeping, according to the researchers.
Those with lower memory scores had fewer slow oscillations on their EEGs during REM sleep. This suggested a less deep sleep.
“In people, slow brain oscillations are characteristic of SWS [short-wave sleep] and linked to the activity of the so-called glymphatic system, a transport system that removes protein waste products from the cerebrospinal fluid,” Olby explained in a journal news release. “The reduction in slow oscillations in people with Alzheimer’s, and the associated reduction in the elimination of these toxins, has been linked to worse memory consolidation during deep sleep.”
Dogs with poorer memory had more pronounced rapid beta waves. These waves are typical of wakefulness in healthy people and dogs. This finding also indicated that dogs with CCDS sleep less soundly.
Dogs that also did worse on a task measuring attention span also had tighter coupling in delta waves between the two brain hemispheres, which is also seen in people with dementia.
The researchers cautioned that it is not yet known whether the nap changes would also be seen in the dogs’ nocturnal sleep.
“Our next step will be to follow the dogs over time throughout their adulthood and later life to determine if there are early markers in their sleep-wake patterns, or in the electrical activity of their brain during sleep, that could predict the future development of cognitive dysfunction,” Olby said.
More information
Texas A&M University has more on cognitive decline in aging dogs.
FOUNTAIN: Frontiers in veterinary sciencepress release, April 28, 2023
—————————————————-
Source link