How cats with dementia could help crack the Alzheimer’s puzzle

Scientists discovered a build-up of the toxic protein amyloid-beta in the brains of cats with the condition - one of the defining features of Alzheimer's disease.

The findings offer a clearer picture of how amyloid-beta may lead to age-related brain dysfunction and memory loss in cats, experts say.

Many older cats develop dementia, leading to behavioral changes such as increased vocalization - or meowing - confusion and disrupted sleep - symptoms similar to those seen in people with Alzheimer's disease.

Scientists at the University of Edinburgh examined the brains of 25 cats of different ages after they had passed away, including those with signs of dementia.

Powerful microscopy images revealed a build-up of amyloid-beta within the synapses - connections between brain cells - of older cats and cats with dementia.

Synapses allow the flow of messages between brain cells and are vital to healthy brain function. Their loss strongly predicts reduced memory and thinking abilities in humans with Alzheimer's disease.

The research team also found evidence that astrocytes and microglia - types of support cells in the brain - engulfed or 'ate' the affected synapses. This process, called synaptic pruning, is important during brain development but can contribute to synapse loss in dementia.

Experts say the findings will not only help to understand and manage dementia in cats but, given their similarities, could also contribute to the development of future treatments for people with Alzheimer's disease.

Scientists studying Alzheimer's disease in the past have relied heavily on genetically modified rodent models. Rodents do not naturally develop dementia, and studying cats with dementia has the potential to advance knowledge and help develop treatments for both cats and people, experts say.

The study, funded by Wellcome and the UK Dementia Research Institute, is published in the journal European Journal of Neuroscience. The research team included scientists from the Universities of Edinburgh and California, UK Dementia Research Institute and Scottish Brain Sciences.

Dr Robert McGeachan, study lead from the University of Edinburgh's Royal (Dick) School of Veterinary Studies, said: "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. 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."

Professor Danièlle Gunn-Moore, Personal Chair of Feline Medicine at the Royal (Dick) School of Veterinary Studies, said: "Feline dementia is so 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. Feline dementia is the perfect natural model for Alzheimer's, everyone benefits."