One in four elderly people has Alzheimer’s

 One in four elderly people has Alzheimer’s, a study suggests.

It was previously thought that around seven per cent of over-70s suffered with the condition, but data from 11,000 people found the true prevalence to be more than three times higher at 25.2 per cent.

The study, by King’s College London, is the first population-based research into how widespread signs of Alzheimer’s are in the brains of older people

It found that it was more common in the oldest people in society than previous studies suggest, but less prevalent in younger people than previously thought.

Alzheimer’s is the biggest killer in the UK and accounted for one in eight of all deaths in 2024 in England and Wales, according to official statistics.

Scientists looked for signs of alterations in the brain, known as Alzheimer’s disease neuropathological changes (ADNC), and found the overall rate of Alzheimer’s in over-70s was about one in ten.

This, they say, would make ten per cent of over-70s eligible for monoclonal antibody treatments that are capable of slowing cognitive decline.

ADNCs are chunks of protein in the brain which are made when neurons and synapses die. They are a reliable indicator of Alzheimer’s, the scientists say, but are hard to test for and not routinely performed by the NHS.

Blood sample analysis of Norwegian study participants found the signs of Alzheimer’s hallmarks increased with age.

Around eight per cent of people 65 to 69 had signs of disease, data show, rising to almost two-thirds of study participants over the age of 90.

There was no significant difference between males and females, data show, contradicting the theory that women are more affected by dementia than men. 

“Our study used a simple blood test to establish changes that contribute to cognitive impairment in those with dementia,” said study author Prof Dag Aarsland, of Old Age Psychiatry at King’s.

“In doing so, we found that around 11 per cent of participants over the age of 70 meet the eligibility criteria for monoclonal antibody treatments that can potentially slow the impact of cognitive decline in these individuals.”