Your Cat’s Brain Could Hold Secrets to Alzheimer’s

Advances in veterinary medicine have extended the lifespan of our fluffy companions. But this comes with a downside: More than one in four cats over the age of 11 develops at least one sign of dementia, such as confusion, forgetting their training, trouble with sleep, and disorientation. Other animals, including dogs and dolphins, also develop dementia, but it isn’t clear whether the disease process is similar to the human disease.

Robert McGeachan, a researcher at the University of Edinburgh’s Royal (Dick) School of Veterinary Studies, was curious whether the same proteins implicated in driving Alzheimer’s in humans might cause similar symptoms in cats. Previous studies found beta-amyloid and tau proteins, hallmarks of Alzheimer’s, in the autopsied brains of older cats but didn’t compare them to cats with dementia.

His new study, published in the European Journal of Neuroscience, found that the autopsied brains of cats with dementia had more beta-amyloid and inflammation in their brains than healthy older and younger cats. “We see beta-amyloid directly accumulating within synapses, the connections between cells,” McGeachan told Being Patient. 

Damage to these connections is a signature of the disease and an indicator of impending cognitive decline in humans. “If we can protect the synapses,” McGeachan said, “we can protect against cognitive decline.” 

Could figuring out treatments for pets lead to new drugs for humans?

 Is cat dementia the same as Alzheimer’s in humans?

The researchers compared the autopsied brains of seven young healthy cats, 10 healthy older cats, and eight cats with dementia. Under a microscope, McGeachan and his colleagues looked at the levels of beta-amyloid proteins and analyzed the brain’s immune cells microglia and astrocytes.

Just as in humans, beta-amyloid proteins in cats build up with age. The researchers spotted microglia and astrocytes gobbling up these proteins in both the older cats and those with dementia. But here’s the key difference: Cats with dementia had more plaques, and thus more inflammation and destruction of synapses, factors that could explain the symptoms.

One limitation, McGeachan said, was that they didn’t look at tau. In humans, this protein accumulates in the brains of people with Alzheimer’s and correlates with cognitive decline and disease progression. 

Could a treatment for cats translate to humans?

Most Alzheimer’s drugs that show promise in rodents fail in human clinical trials. In part, that might be because these animals don’t naturally develop dementia and require genetic modification to develop the symptoms and protein traits of the disease. Cats might be a better model since they naturally develop a similar form of dementia as humans. 

“The drugs that are effective in treating cat dementia might be more likely to translate,” McGeachan said. That potentially could lead to new treatments for both people and pets.

Drugs that work in pets sometimes do get tested and approved in humans. The most famous example is the anti-parasite drug ivermectin. PAC-1, an anti-cancer drug for dogs now entering early-stage human trials. There’s even a company developing Alzheimer’s treatments for humans based on a successful trial in dogs with dementia.

In the meantime, McGeachan said it’s important to recognize the signs of dementia in feline companions. Pet owners generally view such changes as a normal part of animal aging, similar to humans. Now there’s growing evidence pointing to a disease process, opening the door for new trials to slow or even halt the disease in its tracks.