Cats with dementia have brain changes strikingly similar to humans

Cats that develop dementia may play an important role in helping scientists better understand Alzheimer’s disease in humans.

According to new research from the University of Edinburgh, the brains of these cats show many of the same changes seen in people living with Alzheimer’s.

One of the most significant similarities is the build-up of harmful proteins, such as amyloid-beta, inside the brain. These proteins can collect around and within synapses – the tiny structures that carry signals between nerve cells – and interfere with their function.

Over time, this damage disrupts communication between brain cells, which can lead to problems with memory, thinking, and behavior, just as it does in human patients.

How dementia appears in cats

Older cats that develop cognitive dysfunction often begin to show noticeable changes in their behaviour. One common sign is that they start meowing more frequently, and this increase in vocalisation is often most pronounced at night.

They may also appear disoriented or confused, sometimes seeming unsure of familiar surroundings.

Many cats alter the way they interact with their owners, either becoming unusually needy or, in some cases, more withdrawn. Some may even forget long-established litter box habits, leading to accidents around the home.

Their normal sleep-wake patterns can also become disrupted, with restlessness at night and increased sleeping during the day. These behavioral changes strongly resemble the symptoms observed in people with Alzheimer’s disease.

Cognitive decline in cats

To investigate what might be happening in the brain, researchers examined samples from three groups of cats – young animals, older animals without dementia, and older animals diagnosed with dementia.

When they compared these brains, the experts found that the older and dementia-affected cats both had deposits of amyloid-beta within their synapses.

Synapses are the critical junctions that allow nerve cells to pass electrical and chemical messages to one another, enabling normal thought, memory, and learning.

When amyloid-beta builds up in these areas, it can interfere with signal transmission. This kind of disruption can quickly impair memory and thinking abilities, contributing to the cognitive decline seen in both cats and humans.

What happens inside the brain

The study revealed more than just protein build-up. In areas with amyloid-beta, the brain’s support cells – microglia and astrocytes – became more active. These cells help maintain the brain, but in this case, they were swallowing synapses.

This process, called synaptic pruning, is normal when the brain is still developing. Later in life, too much pruning can cause lasting memory loss.

Microglia were especially aggressive near amyloid-beta plaques. They often took in synapses already containing the protein.

Astrocytes did this too, though less often. In cats with dementia, the amount of amyloid-beta was closely linked to how many synapses were being removed. That link wasn’t as clear in healthy older cats.

Why this matters for people

Most Alzheimer’s research uses rodents, but rodents don’t naturally get dementia. Cats do. That makes them a more realistic model for testing new treatments and understanding the disease’s progression in real life.

“Dementia is a devastating disease – whether it affects humans, cats, or dogs. Our findings highlight the striking similarities between feline dementia and Alzheimer’s disease in people,” noted Dr. Robert McGeachan from the University of Edinburgh’s Royal (Dick) School of Veterinary Studies.

“This opens the door to exploring whether promising new treatments for human Alzheimer’s disease could also help our aging pets.”

“Because cats naturally develop these brain changes, they may also offer a more accurate model of the disease than traditional laboratory animals, ultimately benefiting both species and their caregivers.”

Benefits of cat dementia research

Professor Danièlle Gunn-Moore, Personal Chair of Feline Medicine at the Royal (Dick) School of Veterinary Studies, noted that feline dementia is very distressing for the cat and for its person.

“It is by undertaking studies like this that we will understand how best to treat them. This will be wonderful for the cats, their owners, people with Alzheimer’s and their loved ones,” said Gunn-Moore. “Feline dementia is the perfect natural model for Alzheimer’s, everyone benefits.”

The study strengthens the idea that the same harmful processes in humans can appear in cats – and that both species could benefit from the same future treatments.

The research is published in the European Journal of Neuroscience.

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