Older dogs who sleep badly may have dementia, study says
In a veterinary lab in North Carolina, Woofus, a 15-year-old basset hound mix, is allowing researchers to attach an electroencephalogram, or EEG, electrodes to his head before padding off to a dark, cozy room for an afternoon nap.
During his snooze, the study team will analyze Woofus’ brain waves to judge the quality of his sleep. Woofus has canine cognitive dysfunction syndrome, or CCDS, the doggie disorder that’s similar to Alzheimer’s disease in people. The elderly dog’s owners say he is struggling to get enough rest at night.
“Just like humans with Alzheimer’s disease, dogs with CCDS experience sleep disruptions, such as insomnia and sleep fragmentation,” said veterinarian Dr. Natasha Olby, a professor of neurology, neurosurgery and gerontology at North Carolina State College of Veterinary Medicine in Raleigh.
Woofus isn’t the only sleep-deprived dog in this study. On other days in the clinic, Jake, a 13-year-old pointer, and Coco, a 12-year-old dachshund, among others, might be taking a siesta while researchers peer inside their brains.
“Owners of dogs with CCDS report their dogs suffer from difficulty sleeping at night, increased sleeping during the day or both, as well as pacing and vocalizations at night,” Olby said. “This can be very hard on the dog’s owners — not only are they worried for their pet, their sleep is also significantly disrupted.”
To find out whether sleep problems in dogs indicate early signs of dementia as they do in people, Olby and her team turned to a group of senior dogs enrolled in an ongoing study testing antiaging supplements. The dogs visit twice a year “and do all kinds of really fun cognitive testing,” she said. “They really enjoy it and like the handlers they work with.”
To be considered for the antiaging study, the dog must have lived more than 75% of the expected life span for their breed or mix of breeds. A dog also could not be crippled by arthritis or going blind, as the pet needed to be able to perform tasks designed to test their cognitive capabilities.
A dog might be asked, for example, to find a treat hidden under a cup or a snack inside a cylinder in which one end had been closed by a researcher. By repeating the tasks at the clinic every six months, any decline in the dog’s mental agility or performance can be tracked.
For the new study measuring a dog’s brain waves during sleep, researchers used a form of electroencephalogram called polysomnography, used in sleep clinics to diagnose sleep problems in people.
“It’s the gold standard method to look at what the brain is doing during sleep,” Olby said, adding this is the first canine study to apply the same technology used on humans.
“We glue these electrodes on with a really great conductive glue that’s water soluble. Then we just wash it off afterwards,” she said. “We don’t use anywhere near as many electrodes as you see on people in a sleep lab, because dogs have far less cortex and surface area to cover.”
Already at ease with the staff, it wasn’t too difficult to train 28 senior dogs to wear electrodes and walk around with dangling wires without complaint, she said.
To make the dogs more comfortable during their siestas, owners bring their dogs’ beds from home, which are placed in a protected room with white noise.
“Staff sit with them while they nap to make sure that they’re not trying to pull out or eat the electrodes or do anything that might hurt them,” Olby said.
When sleeping brain waves were compared with a dog’s cognitive testing, researchers found that dogs with greater dementia spent less time in deep and REM sleep, just as people do. The study was recently published in the journal Frontiers in Veterinary Science.
“Dogs that did worse on our memory tests had levels of REM sleep which were not as deep as they should be,” Olby said. “We found the same when it came to deep sleep.”
While no one knows the exact mechanism at work — either in people or in dogs — research like this study may help scientists better understand the process and find ways to treat it, Olby said.
“There’s a possibility we might be able to identify an early signature of change on the EEG that can tell us, ‘Hey, things are starting to slide.’ Because with a chronic neurodegenerative process, of course we’d love to be able to intervene sooner rather than later.”
In the meantime, there are medications for anxiety and melatonin for sleep that veterinarians can prescribe as a dog ages, Olby said. And as with people, diet and exercise appears to be a factor.
“There’s been some very nice studies showing diets that are enriched in flavonoids and antioxidants and medium-chain fatty acids could possibly slow the development of dementia in dogs,” she said. “It’s just like people — if you can eat a Mediterranean diet and do your exercise, you’re going to do better.”
Doggie dementia is a worrisome reality for many senior dogs. Research has found that by 11 or 12 years of age, 28% of dogs had mild and 10% had severe cognitive impairment. By the time the dogs reached age 15, the risk had risen to 68% for mild and 35% for severe cognitive impairment. A 2022 study found the odds of canine cognitive dysfunction increased by 52% with each year of age, Olby said.
Pet owners can look for signs that their dog’s mental functions are declining. According to Olby, vets use an acronym called DISHA-AL, which stands for disorientation, interaction changes, sleep/wake cycle alterations, house soiling; activity changes (increased or decreased); and anxiety and learning & memory.
“One of the earliest signs is you’ll start to see a little confusion just like you do with people, they suddenly start to make some mistakes and things you wouldn’t expect them to do. Very similar to us,” Olby said.
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Dogs may also lose learned behaviors, or forget their house training and begin to have unintentional accidents around the house, she added.
“A classic problem is wandering around and getting lost under the table or something — they just can’t process the information and figure out where they are. Changes in sleep cycle, increased anxiety, all of these things are classic signs of dementia,” she said.
Don’t assume that is what is wrong with your dog, however. Just like in people, other health problems such as metabolic disease, urinary tract infections or even brain tumors can mimic classic signs of dementia.
“High blood pressure can make dogs anxious, for example,” Olby said, “so a vet needs to thoroughly check the dog to rule out disease.”