New Study Examining Role of Sleep Disorders in Dogs with Dementia

Dogs with dementia suffer from the same sleep problems as humans with dementia. In a new study, researchers at North Carolina State University performed electroencephalography (EEG) on older dogs to determine whether EEG readings during sleep correlated with signs of cognitive decline. They found that dogs with more advanced dementia had more sleep disturbances and slept less overall than dogs with normal cognition.

This study was part of an ongoing Canine Aging and Cognition clinical trial at North Carolina State University and included 28 older dogs (17 females and 11 males). Prior to the sleep study, dogs underwent a complete physical examination, underwent cognitive testing, and owners completed the Canine Dementia Scale (CADES) questionnaire to determine the severity of cognitive decline.

Researchers used non-invasive techniques to collect the data. The dogs were not sedated and the electrodes were attached to the skull with an adhesive gel. The dog performed his two sleep sessions in the lab. The first was to acclimatize the dog to the environment and placement of the electrodes, and the second was to record brain activity during her two-hour sleep period.

“Previous dog sleep studies have often surgically implanted electrodes,” said Alejandra Mondino, a postdoctoral researcher at North Carolina State University and lead author of the study. “Noninvasive research is relatively new. We are one of her few groups doing this work.”

EEG measured four stages of sleep: wakefulness, sleepiness, non-REM, and REM. Non-REM or non-REM is the deep sleep state that precedes REM (representing rapid eye movements and associated with dreaming).

“In NREM, the brain clears toxins, including the beta-amyloid protein, which is implicated in diseases such as Alzheimer’s disease,” Mondino says. “REM sleep is when we dream, and this stage is very important for memory consolidation.”

The researchers correlated the percentage of time spent in each sleep state with scores on the dogs’ cognitive tests and the CADES questionnaire. The higher the dog’s dementia score, the less time it spends in non-REM and REM sleep.

“These dogs have dementia and sleep disturbance is part of it,” says Mondino. “In addition to the short amount of time spent in sleep, looking at the EEG, we found that brain activity during sleep is similar to wakefulness.

“In other words, even though they can sleep, their brains aren’t really asleep.”

This work is an important part of establishing a baseline for identifying cognitive decline in dogs. The researchers hope this study will lead to early diagnosis and intervention in older dogs showing signs of cognitive decline.

“EEG signatures have been found to be useful indicators of cognitive impairment in dogs,” said Kady M. Gjessing, Ph.D., and Rahna M. Davidson, Distinguished Chairs of Gerontology, North Carolina, and corresponding authors of the study. says one Natasha Olby. “This study further establishes dogs as a model for Alzheimer’s disease. We hope that treatment trials in dogs will help guide choices in developing treatments for people.”

works appeared in Frontiers of veterinary medicine Supported by Kady M. Gjessing and Rahna M. Davidson Distinguished Chair in Gerontology, Sleep Research Society Foundation (Grant 04-SRG-21), and Company of Biologists (Grant DMMTF2205727).

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Note to editors: a summary follows.

“Sleep and cognition in aging dogs.

Soil: 10.3389/fvets.2023.1151266

author: Alejandra Mondino, Michael Khan, Claire Ludwig, Margaret Elizabeth Gruen, and Natasha J. Olby (North Carolina State University). Magaly Catanzariti, Santa Fe Coast Applied Mathematics Institute, Argentina. Diego Martin Mateos, Santa Fe Coast Applied Mathematics Institute, Argentina, Autonomous University of Entre Ríos (UADER), Entre Ríos, Argentina. Anna Kis, Research Center for Natural Science, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
Release: April 28, 2023 Frontiers of veterinary medicine

overview:
INTRODUCTION: Sleep is fundamental to cognitive homeostasis, especially in the elderly, because the clearance of amyloid-beta (key to the pathophysiology of Alzheimer’s disease) occurs during sleep. Several EEG features of sleep and wakefulness have been considered hallmarks of dementia. Owners of dogs with canine cognitive dysfunction syndrome (the canine analogue of Alzheimer’s disease) report that their dogs suffer from sleep disturbances. The aim of this study was to quantify age-related changes in the macrostructure and EEG features of the sleep-wake cycle in senior dogs and to correlate them with cognitive performance.
METHODS: Polysomnographic recordings were performed in 28 senior dogs during a 2-h afternoon nap. Percentage of time spent in wakefulness, sleepiness, non-REM sleep, REM sleep, and latencies to three sleep states were calculated. The spectral power, coherence, and Lempel-jib complexity of brain oscillations were estimated. Finally, cognitive ability was assessed by the Canine Dementia Scale questionnaire and a battery of cognitive tests. Correlations between age, cognitive ability, sleep-wake cycle macrostructure and EEG features were calculated.
RESULTS: Dogs with higher dementia scores and poorer performance on problem-solving tasks had shorter periods of NREM and REM sleep. In addition, quantitative EEG analysis showed age- or cognitive performance-related differences in dogs, some of which reflected less sleep in the more affected dogs.
Discussion: Polysomnographic recordings in dogs can detect changes in sleep-wake cycles associated with dementia. Future studies should evaluate its potential clinical use for monitoring the progression of canine cognitive dysfunction syndrome.