In a recent study published in Frontiers in Veterinary Science, scientists have discovered that dogs with canine cognitive dysfunction syndrome (CCDS) – the canine equivalent of dementia in humans – experience similar disruptions in sleep rhythms and reductions in delta brain waves as human Alzheimer’s patients.
This groundbreaking research sheds light on the possible similarities in the development and progression of dementia in both humans and dogs, and could potentially pave the way for further studies on the subject.
Alzheimer’s disease is well-known for causing disruptions in sleep rhythms in its earliest stages. Affected individuals often experience daytime sleepiness, agitation or confusion around dusk, staying awake longer, and frequently waking up at night. This is believed to stem from damage to the sleep-regulating areas of the brain.
Alzheimer’s patients typically spend less time in both REM and non-REM sleep, with the most significant reduction occurring in slow-wave sleep (SWS), a stage of non-dreaming deep sleep characterized by slow “delta” brain waves (0.1 to 3.5 Hz). This is the stage during which day-time memories are consolidated.
The study was led by Dr. Natasha Olby, a professor of Veterinary Neurology and Neurosurgery at North Carolina State University. The researchers found that dogs with CCDS experienced a similar reduction in sleep time and delta brain waves. This implies that these dogs sleep less and less deeply, echoing the sleep disruptions observed in Alzheimer’s patients.
“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,” said Dr. Olby.
The study involved 28 senior mixed- and full-breed dogs, both male and female, aged between 10.4 and 16.2 years, which corresponds to between 81% and 106% of their average lifespan, depending on size.
The owners of these dogs were asked to complete a questionnaire about their canine companions, rating the severity of CCDS symptoms like disorientation, poor social interactions, and house soiling.
Additionally, the researchers conducted examinations of the dogs for potential orthopedic, neurological, biochemical, and physiological co-morbidities.
Based on the findings, 28.5% of the dogs were classified as normal, while the remaining participants were classified with varying degrees of CCDS: 28.5% with mild, 14.3% with moderate, and 28.5% with severe CCDS.
The research team then conducted a series of cognitive tests on the dogs to assess their attention, working memory, and executive control. One such test, the ‘detour task’, required a dog to retrieve a treat from a horizontal transparent cylinder by accessing it from either end.
The task was made more challenging by blocking off the dog’s preferred side, forcing them to demonstrate cognitive flexibility to detour to the other end of the cylinder.
Dr. Alejandra Mondino, a postdoctoral fellow in Dr. Natasha Olby’s research group at North Carolina State University, and her colleagues performed polysomnography studies on dogs to investigate the relationship between canine cognitive dysfunction syndrome (CCDS) and sleep patterns.
The study’s findings suggest that dogs with CCDS exhibit changes in sleep-wakefulness cycles that resemble those observed in people with Alzheimer’s disease.
The polysomnography studies were conducted in a quiet room with dim light and white noise, simulating a sleep clinic environment. The dogs were allowed to spontaneously take an afternoon nap while electrodes measured their brain waves, electrical activity of the muscles and heart, and eye movements.
The measurements lasted up to two hours but were stopped if the dogs became anxious, attempted to leave the room, or removed the electrodes. Out of the dogs studied, 93% entered drowsiness, 86% entered non-REM (NREM) sleep, and 54% entered REM sleep.
The results of the study demonstrated that dogs with higher dementia scores and those who performed poorly on the detour task took longer to fall asleep and spent less time sleeping, and this held true for both NREM and REM sleep.
Furthermore, dogs with poorer memory scores exhibited changes, such as fewer slow oscillations in their electroencephalograms during REM sleep, suggesting that they slept less deeply during this phase.
“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,” explained Dr. 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.”
Interestingly, dogs with poorer memory displayed more pronounced fast beta waves, between 15.75 and 19 Hz. Strong beta waves are typical of wakefulness in healthy people and dogs, and are not considered normal during sleep, which once again indicates that dogs with CCDS sleep less deeply.
Additionally, dogs that performed poorly in the ‘sustained gaze’ task, which measures attention span, demonstrated tighter coupling in delta waves between the two brain hemispheres, a result also found in people with dementia.
While the study’s findings show similarities between CCDS and Alzheimer’s, the authors caution that it is still unknown if these changes occur during dogs’ nighttime sleep rather than their afternoon naps.
“Our next step will be to follow dogs over time during their adult and senior years to determine if there are any early markers in their sleep-wakefulness patterns, or in the electrical activity of their brain during sleep, that could predict the future development of cognitive dysfunction,” said Dr. Olby.
This innovative study highlights the potential for further research into the similarities between the development of dementia in dogs and humans. By understanding the connection between CCDS and Alzheimer’s disease, researchers may uncover valuable insights into the development, progression, and potential treatment options for both conditions.
Dementia in dogs, also known as Canine Cognitive Dysfunction Syndrome (CCDS), is a neurodegenerative condition that affects a dog’s cognitive abilities, behavior, and memory. It is often compared to Alzheimer’s disease in humans, as both conditions share similar symptoms and underlying causes.
CCDS is more prevalent in senior dogs, with studies suggesting that over 50% of dogs aged 11 years and older may show signs of cognitive decline.
Dogs with dementia may appear confused or lost, even in familiar environments. They may wander aimlessly, become stuck in corners or behind furniture, or have difficulty navigating around obstacles.
Affected dogs may forget previously learned commands, routines, or house training, leading to accidents indoors. They may also fail to recognize familiar people, pets, or objects.
Dogs with dementia may experience disrupted sleep-wake cycles, resulting in increased daytime sleepiness, restlessness at night, and changes in overall sleep quality.
Dogs with CCDS might show reduced interest in socializing with people or other pets, display irritability or aggression, or exhibit increased clinginess or separation anxiety.
Dementia can cause dogs to lose interest in play, exercise, or exploring their environment, leading to an overall decrease in activity levels.
The exact cause of CCDS is not well understood, but it is believed to involve the accumulation of protein deposits in the brain, called beta-amyloid plaques, which interfere with normal brain function.
Additionally, factors such as oxidative stress, inflammation, and reduced blood flow to the brain may contribute to the development and progression of the condition.
There is no cure for dementia in dogs, but treatment options are available to manage the symptoms and improve the quality of life for affected dogs.
Certain drugs, such as selegiline (Anipryl), have been shown to alleviate some symptoms of CCDS by increasing the levels of dopamine in the brain, which is involved in cognitive function and mood regulation.
Supplements containing antioxidants, omega-3 fatty acids, and other nutrients, such as phosphatidylserine and B vitamins, may help support cognitive function and overall brain health.
Providing mental and physical stimulation through interactive toys, puzzles, or games can help maintain cognitive function and slow the progression of CCDS.
Maintaining a predictable daily routine, including regular feeding times, walks, and play sessions, can help minimize stress and confusion for dogs with dementia.
Regular check-ups with a veterinarian are essential for monitoring the progression of CCDS and adjusting treatment plans as needed.
It is important to consult with a veterinarian if you suspect your dog is showing signs of dementia, as some symptoms can also be indicative of other medical conditions that require different treatments.
Early intervention and management can help improve your dog’s quality of life and potentially slow the progression of cognitive decline.