Cats with dementia reveal new clues about Alzheimer’s disease in humans

As cats grow older, some begin to show strange new behaviors. They may start meowing more often, seem confused, or struggle to sleep through the night. While these symptoms might be easy to dismiss as normal aging, they could point to something more serious: feline dementia.

A new study from the University of Edinburgh has found that cats with dementia show brain changes similar to those seen in people with Alzheimer’s disease. For the first time, researchers have clearly linked the toxic buildup of amyloid-beta — a protein long associated with Alzheimer’s — to aging cats’ brains. This discovery opens new doors for understanding not just feline cognitive decline, but also how Alzheimer’s affects humans.

To dig deeper into this mystery, scientists at the university’s Royal (Dick) School of Veterinary Studies studied the brains of 25 cats of various ages. Some of these cats had shown signs of dementia before they died. By using advanced microscopy, the team was able to zoom in on the brain’s tiniest structures.

What they found was striking. The brains of older cats and those with dementia were filled with amyloid-beta plaques. These toxic clumps were especially concentrated in synapses — the small spaces between brain cells where information flows. In both cats and people, healthy synapses are essential for memory and learning. When amyloid-beta starts to build up, these connections break down, and thinking becomes slower and more difficult.

“Dementia is a devastating disease — whether it affects humans, cats, or dogs,” said Dr. Robert McGeachan, the lead researcher. “Our findings highlight the striking similarities between feline dementia and Alzheimer’s disease in people. This opens the door to exploring whether promising new treatments for human Alzheimer’s disease could also help our aging pets.”

But that wasn’t all the researchers discovered. They also found that two kinds of brain support cells — astrocytes and microglia — were involved in something called synaptic pruning. This process is normal and even helpful during brain development, where extra synapses are cleared away to make room for more efficient brain function.

In older cats, though, this pruning appeared to go too far. The astrocytes and microglia had started to “eat” healthy synapses affected by amyloid-beta. While this reaction might be the brain’s way of trying to clean up the mess, it could also be making the problem worse by speeding up memory loss.

In humans with Alzheimer’s, the same overactive pruning by microglia has been linked to cognitive decline. By finding the same process in cats, researchers now have a natural model that may help them better understand how this harmful cycle begins and spreads.

For many years, scientists studying Alzheimer’s disease have relied on rodents — mostly mice — that were genetically altered to develop the condition. But these animals don’t naturally experience dementia, and the changes in their brains don’t fully match those found in humans. That’s made it harder to develop drugs that truly work in people.

Cats, however, are different. Like humans, they naturally develop amyloid-beta buildup and show real-life symptoms of memory loss and confusion. By studying the brains of cats who age and decline naturally, researchers may have found a more accurate and useful model for Alzheimer’s disease.

“Because cats naturally develop these brain changes, they may also offer a more accurate model of the disease than traditional laboratory animals,” Dr. McGeachan said. “Ultimately, this could benefit both species and their caregivers.”

The team hopes their findings will improve both veterinary care for older cats and research into Alzheimer’s treatments for humans. Pet owners could benefit, too, by recognizing the early signs of cognitive decline and seeking help sooner.

This work was supported by Wellcome and the UK Dementia Research Institute, and was conducted in collaboration with researchers from the University of California and Scottish Brain Sciences. The findings were published in the European Journal of Neuroscience.

The researchers now plan to study larger groups of cats and explore whether these brain changes can be tracked while the animals are still alive. They also want to investigate how lifestyle factors — such as diet, activity, and social interaction — affect the risk of feline dementia. These same questions are being asked in human Alzheimer’s studies, and cats may offer clues that apply to both species.

The study’s focus on the role of synapse loss, microglial pruning, and amyloid-beta build-up reflects the direction of many current Alzheimer’s investigations. With the failure of many drugs that targeted only amyloid-beta, scientists are now trying to understand the bigger picture — including inflammation, immune responses, and how the brain’s natural clean-up systems might go wrong.

Though a cure remains far off, the better we understand how dementia begins and spreads, the closer we get to slowing it down. And thanks to a few curious cats, we may now be a little closer.

Note: The article above provided above by The Brighter Side of News.

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