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Is THIS the reason women are twice as likely to develop dementia as men? Menopause takes the brakes off ‘dangerous protein,’ scientists show for the first time
- About two-thirds of the 5 million Alzheimer’s patients in the United States are women.
- Scientists used to think this was because they lived longer than men.
- But now a new study suggests that the difference could be related to menopause.
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Scientists may be one step closer to finding out why women are so much more likely than men to develop dementia.
They discovered that changes that occur during 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 in men.
Estrogen acts as a natural anti-inflammatory and is believed to play a role in C3 suppression. While sex hormone levels in men rise as they age, estrogen plummets in women during menopause.
There is increasing evidence on the role of menopause in the development of Alzheimer’s disease.
Scientists may be one step closer to finding out why women are so much more likely than men to develop dementia, and it could be linked to menopause (file image)
About two-thirds of the 5.8 million dementia patients in the United States are women, statistics suggest. The division is the same in the UK.
Alzheimer’s is a life-changing disease in which people lose the ability to remember events, walk, and even feed themselves in later stages.
There are currently no drugs that can reverse its effects, although a drug nearing approval has been shown to slow the condition in trials.
In the latest study, published today in Progress of sciencethe experts looked at 40 brains of men and women.
They were evenly split by gender, and half were people who had died from Alzheimer’s disease.
The tests revealed 1,449 different types of proteins in the brain that form as people age, several of which have already been linked to Alzheimer’s disease, including C3.
Scientists at the Scripps Research Center in San Diego, California, suggested that menopause may be behind the increased risk of Alzheimer’s in women. A key part of the body’s immune system, complement proteins, can bind with nitric oxide to form “storms” of edited proteins. This is normally prevented by estrogen, the scientists suggested. But in women, levels of this hormone drop after menopause, putting them at greater risk. The study found that levels of edited complement C3 were six times higher in female brains with Alzheimer’s compared to men affected by the disease. These higher levels cause inflammation and can also cause immune cells to start breaking down synapses in neurons, disrupting communication between them, a hallmark of Alzheimer’s disease.
Complement proteins, such as C3, trigger inflammation in cells to help fight infection.
However, they can react with nitric oxides, forming a type of ‘modified’ supplement that can cause a ‘storm’ in the body, increasing the risk of Alzheimer’s.
Normally, the modified proteins are removed by the sex hormone estrogen.
But in women, a drop in levels after menopause removes this protection, the scientists suggest.
Previous studies have shown that, in addition to causing inflammation, modified proteins in the brain can activate immune cells in the organ, called microglia.
These attack and destroy synapses in neurons, stopping communication between cells. In Alzheimer’s, patients have significant loss of synapses.
Previous research on human brain cells in the laboratory has also revealed that reduced estrogen levels lead to increased levels of the modified C3 protein.
Dr. Stuart Lipton, an expert in molecular medicine 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.”
She added: “Why women are more likely to get Alzheimer’s disease has long been a mystery, but I believe our results represent an important piece of the puzzle that mechanistically explains women’s increased vulnerability as they age.” .