A new study has found that humans and cats develop dementia in similar ways, offering what scientists say are new opportunities to research conditions like Alzheimer’s disease.
The study by a team of U.K. neurological and veterinary researchers examined the brains of 25 cats donated to science after their deaths, including eight that previously showed signs of cognitive dysfunction syndrome (CDS), also known as feline dementia.
Brain scans of older and CDS-affected cats showed the build-up of amyloid-beta, a misfolded protein commonly associated with Alzheimer’s. Researchers say the protein can cause damage to the synapses that carry information through the brain.
Once overloaded with excess protein, synapses become inflamed and even destroyed in an immune response called “synaptic pruning,” which ultimately worsens dementia.
Amyloid-beta build-up in the feline brain samples “mirror(ed)” conditions seen in Alzheimer’s patients, the study found, suggesting that parallel research into treatments could benefit both species.
“If we can successfully develop treatments for treating cat dementia, these might also be more successful at treating human dementia, and also, the opposite’s true,” said lead researcher Robert McGeachan in a Thursday interview.
Dementia in cats
Feline and human dementia show similar symptoms, including memory loss and cognitive decline. Pet owners may notice their cats are more anxious, vocal and visibly confused as they age, with unusual sleep or social patterns and increasing difficulty keeping clean.
One study estimated that more than one in four cats over the age of 11 showed signs of feline CDS, a proportion that rose to one in two after age 15.
Though age-related decline in cats is widely known, the discovery that CDS shares similarities with human dementia could prove helpful in shedding light on Alzheimer’s — which McGeachan notes is notoriously difficult to study and treat.
“We’ve been studying it for decades, we spent billions and billions of dollars in research, and ... compared to other disorders, the progress has been fairly slow and fairly poor,” he told CTVNews.ca.
“One argument that’s always discussed is that actually, the models we’re using aren’t very good. They don’t accurately, kind of, replicate the disease process in humans.”
Previous animal research has focused on mice, which do not develop Alzheimer’s-like symptoms on their own, unless they are first genetically modified. This means that much of the progress made hasn’t easily translated to human medicine.
“We’re very good at treating Alzheimer’s disease in mice … but (treatments have) failed in clinical trials, when they’ve been started to be used in humans,” McGeachan said.
Cats, meanwhile, experience cognitive decline naturally, and what’s more, domestic pets encounter much of the same environmental factors as their owners, making the research that much more transferable.
McGeachan notes that amyloid beta build-up can occur in other animals like dogs, cattle, sheep, monkeys and even dolphins, but the link with possible dementia symptoms hasn’t been confirmed in all species, just yet.
Future research, he says, could explore parallels in other species or involve more longitudinal study of cats living with CDS as they age.
“Feline dementia is so distressing for the cat and for its person,” said study co-author Danièlle Gunn-Moore, in a release.
“It is by undertaking studies like this that we will understand how best to treat them.”
