Women are at greater risk of developing Alzheimer’s because they are prone to higher levels of a toxic protein in the brain, groundbreaking research has suggested.
It has long been known that women are more likely to develop the memory-robbing condition.
However, this was thought to be because they live longer and age is the biggest risk factor for the disease.
Now, American scientists say women who already have a build-up of one toxic protein — amyloid — in the brain accumulated another protein — tau — at a faster rate than their male counterparts.
Significant clumps of both proteins can form plaques and tangles — and this is thought to be behind the symptoms of Alzheimer’s, the leading cause of dementia.
The team, from Harvard University in Boston, said the findings suggested women were at higher risk of the condition because of the ‘elevated risk of this tau build up’.
Experts also claimed the research could impact clinical trials for new Alzheimer’s drugs.
One drug — lecanamab — which slowed progression of the disease by as much as 27 per cent in trials, has already been found to be less effective in women.
Alzheimer’s disease is the most common cause of dementia. The disease can cause anxiety, confusion and short-term memory loss
Significant clumps of both proteins can form plaques and tangle — and this is thought to be behind Alzheimer’s symptoms. Pictured, an Alzheimer’s affected brain, with abnormal levels of amyloid protein clumping together to form plaques
In the new research, scientists assessed six studies involving 1,376 participants with Alzheimer’s, aged 72 on average.
Of these, 401 volunteers were found to have higher levels of amyloid.
Analysis of this group suggested women with higher amyloid levels accumulated tau faster than men in parts of the brain such as the inferior temporal cortex and lateral occipital regions.
These are regions of the organ involved in visual processing and memory, meaning these women were at increased risk of Alzheimer’s.
The authors suggested menopause-related hormonal changes — the accelerated production of the follicle-stimulating hormone and the dramatic loss of estrogen and progesterone — could be driving these greater levels of tau in women.
While separate research has indicated this is the case, the scientists warned that further studies were needed.
Writing in the journal JAMA Neurology, they said their findings suggest it wasn’t just a longer lifespan that left women at increased risk of the memory robbing disorder but this interaction of proteins.
‘The disproportionate rates of Alzheimer’s among women are not only driven by survival bias, but also an elevated female risk for tauopathy’, they added.
Around 900,000 Brits are currently thought to have the memory-robbing disorder. But University College London scientists estimate this will rise to 1.7million within two decades as people live longer. It marks a 40 per cent uptick on the previous forecast in 2017
‘Sex differences in the progression of tau may have clear and imminent implications for treatment enrollment’ of anti-tau drugs such as lecanemab’, they added.
Lecanemab, which patients receive through a drip in their arm every month, works by stimulating the body’s immune system to remove the build up of the harmful protein amyloid in the brains of people with early-stage Alzheimer’s.
In the UK, however, it is only available privately, for an estimated cost of £20,000 per year.
While the drug got the green light from UK medicines regulator, the Medicines and Healthcare products Regulatory Agency (MHRA) last year, the NHS spending watchdog refused to fund it claiming the improvements were not worth the price.
Alzheimer’s is the most common cause of dementia in the UK.
Recent analysis by the Alzheimer’s Society estimates the overall annual cost of the dementia to the UK is £42billion a year, with families bearing the brunt.
An ageing population means these costs – which include lost earnings of unpaid carers – are set to soar to £90billion in the next 15 years.
Around 944,000 in the UK are thought to be living with dementia, while the figure is thought to be around 7million in the US.
Memory problems, thinking and reasoning difficulties and language problems are common early symptoms of the condition, which then worsen over time.
Alzheimer’s Research UK analysis found 74,261 people died from dementia in 2022 compared with 69,178 a year earlier, making it the country’s biggest killer.
