Cats with dementia share signs of human Alzheimer’s

Cats with dementia have brain changes similar to those seen in people with Alzheimer’s disease, offering a valuable model for studying the condition in humans, research shows.  

Scientists at the Royal (Dick) School of Veterinary Studies have discovered that brains of cats with the condition have a build-up of the toxic protein amyloid-beta – one of the defining features of Alzheimer’s disease in humans. 

Their 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 behavioural changes such as increased vocalisation, confusion and disrupted sleep – signs similar to those seen in people with Alzheimer’s disease. 

Scientists conducted post-mortem examinations of the brains of 25 cats of different ages, including those which had shown signs of dementia. 

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

The loss of synapses, which allow the flow of messages between brain cells and are vital to healthy brain function, 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 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 help not only 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 have until now 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. 

The study, funded by the Wellcome Trust and 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.