Is THIS why women are twice as likely to get dementia as men? Menopause takes brakes off ‘danger protein’, scientists show for first time
- About two-thirds of America’s 5million Alzheimer’s patients are women
- Scientists used to think this was because they lived longer than men
- But now a new study suggests the difference could be linked to the menopause
Scientists may be one step closer to uncovering why women are so much more likely than men to get dementia.
They found that changes that happen during the menopause release the brakes on a protein that causes inflammation in the brain.
Tests on the brains of Alzheimer’s patients show that levels of this protein — known as C3 — were six times higher in the brains of women with Alzheimer’s than men.
While the levels of the anti-inflammatory estrogen rise in men as they age, the female sex hormone plunges in women during the menopause.
Evidence is mounting over the role of menopause in dementia, after another study found this year women who have gone through the process are more likely to have ‘hyperintensities’ on their brains raising the risk of the condition.
Scientists from the Scripps Research center in San Diego, California, suggested menopause could be behind women’s higher risk of Alzheimer’s. A key part of the body’s immune system, complement proteins, can bind with nitric oxide forming ‘storms’ of edited proteins. Normally, this is avoided by estrogen, the scientists suggested. But in women levels of this hormone fall after menopause, putting them at higher risk. The study found levels of edited complement C3 were six-fold higher in female brains with Alzheimer’s compared to males affected by the condition. These higher levels prompt inflammation, and can also trigger immune cells to start breaking synapses off neurons — breaking communication between them, a hallmark of Alzheimer’s disease
About two-thirds of America’s 5.8million dementia patients are women, statistics suggest. The split is the same in the UK.
Alzheimer’s is a life-changing disease where people lose the ability to remember events, walk and even feed themselves in later stages.
There is currently no treatment for the condition, and no medicines are available that can reverse its effects.
In the study, published today in Science Advances, experts looked at 40 brains in postmortems.
They were split equally by gender, and half were from people who had died from Alzheimer’s disease.
Tests revealed 1,449 proteins in the brains that had changed as people aged. Several of these have already been tied to Alzheimer’s, including C3.
Complement proteins — such as C3 — trigger inflammation in cells to help fight off an infection.
They can react with nitric oxides, however, forming a ‘modified’ type of complement that can cause a ‘storm’ in the body — raising the risk of Alzheimer’s.
Normally, the modified proteins are removed by the sex hormone estrogen.
But in females a drop in its levels after the menopause removes this protection, scientists suggests.
Previous studies have shown that as well as sparking inflammation, modified proteins in the brain can activate immune cells in the organ — called microglia.
These attack and destroy synapses on neurons, stopping communication between cells. In Alzheimer’s, patients have a significant loss of synapses.
Previous research on human brain cells in the lab has also revealed that lowering estrogen levels led to a rise in levels of the modified C3 protein.
Dr Stuart Lipton, a molecular medicine expert at Scripps Research in La Jolla, California, said: ‘Our new findings suggest that chemical modification of a component of the complement system helps drive Alzheimer’s.
‘This may explain, at least in part, why the disease predominantly affects women.’
He added: ‘Why women are more likely to get Alzheimer’s has long been a mystery, but I think our results represent an important piece of the puzzle that mechanistically explains the increased vulnerability of women as they age.’
***
Read more at DailyMail.co.uk