NC State study finds dogs with dementia suffer from more sleep disruption

Woofus, a participant in the sleep study, gets electrodes placed. (Image: John Joyner, NC State)

Researchers at North Carolina State University performed electroencephalography (EEGs) on elderly dogs to determine whether brain-wave readings during sleep correlated with signs of cognitive decline. According to a university release,¹ the results showed that dogs with a more advanced form of dementia typically suffered more frequently with sleep disruptions and also sleep less overall compared to dogs with normal cognitive function.

The study² tested 28 elderly dogs—17 female and 11 male. Prior to the sleep study, the dogs had received complete physicals, undergone cognitive testing, and their owners completed the Canine Dementia Scale (CADES) questionnaire, in order to determine the severity of their cognitive decline. The researchers used non-invasive techniques to gather their data in which the dogs were not sedated, and the electrodes were affixed to the skull with sticky gel. The researchers conducted 2 sleep sessions—1 to acclimate them to the surroundings and electrode placement, and the second to record brain activity during a 2-hour sleep period. The EEG measured 4 stages of sleep: wakefulness, drowsiness, REM (rapid eye movement) and NREM (non-REM).¹

“Past sleep studies in dogs often involved surgically implanted electrodes,” said Alejandra Mondino, DVM, MSc, PhD, postdoctoral researcher at NC State and lead author of the study, in the release. “Non-invasive studies are relatively new. We are one of a handful of groups doing this work.”

Mondino continued, “In NREM, the brain clears toxins, including the beta-amyloid proteins that are involved in diseases like Alzheimer’s. REM sleep is when dreams happen, and this stage is very important for memory consolidation…These dogs have dementia and sleep disruption is part of that. In addition to the shorter time spent sleeping, when we look at the EEG, we saw their brain activity during sleep was more akin to wakefulness. In other words, when they do manage to sleep, their brains aren’t really sleeping.”¹

The researchers correlated the percentage of time spent in each sleep state with the dogs’ scores on cognitive testing and the CADES questionnaire. The higher the dog’s dementia score, the less time they spent in NREM and REM sleep. The researchers hope that the work can lead to early diagnosis and intervention for elderly dogs with signs of cognitive decline.

References

1. New study looks at role of sleep disruption in dogs with dementia. News release. North Carolina State University. Published April 28, 2023. Accessed May 3, 2023. https://news.ncsu.edu/2023/04/new-study-looks-at-role-of-sleep-disruption-in-dogs-with-dementia/#:~:text=They%20found%20that%20dogs%20with,17%20females%20and%2011%20males.
2. Mondino A, Catanzariti M, Martin Mateos D, Khan M, Ludwig C, Kis A, Gruen M, Olby N. Sleep and cognition in aging dogs. A polysomnographic study. Front Vet Sci. 2023. doi: 10.3389/fvets.2023.1151266