Studies are linking the degenerative brain disease with the drop in oestrogen caused by menopause.The menopause directly affects many of us,yet there's a lot we still don't understand about it. Why it impacts on mood,memory and concentration.But surprisingly,these cognitive effects may hold the key not only to safely treating this change itself,but also to tackling a disease that presents similar symptoms-Alzheimer's.
Changes in the brain that occur during menopause so closely resemble those seen in Alzheimer's that some researchers suggest it may signal the start of the disease."We are trying to find out what happens at the particular time that put brains at risk", says Roberta Brinton,a neuroscientist studying Alzheimer's at the University of Southern California who has turned her attention to the menopause.
That knowledge might lead to new ways to help women deal with the unpleasant symptoms of the menopause.Even better,it is possible that therapies to artificially boost hormone levels could protect the brain from these changes altogether-potentially staving off the ravages of dementia later in life.
The menopause essentially signals the end of a woman's ability to have children.As the number of eggs inside the ovaries dwindles,the amount of oestrogen they produce plummets,too.It is the lack of oestrogen and possibly some of the other hormone released by the ovaries-that is thought to trigger the common symptoms of menopause.These can include hot flushes,fatigue,weight gain,lack of sex drive,and vaginal dryness.
But cognitive effects such as mood swing,insomnia,anxiety and forgetfulness are still often overlooked.This is partly because they may be seen as going hand in hand with ageing."Another potential reason is that the cultural expectation is that women just endure,even if they may be experiencing uncomfortable or disturbing symptoms," says Brinton.
The brain has plenty of oestrogen receptors,so there is nothing new in the idea that a dive in levels of the hormone can have an effect. But until relatively recently,any impacts on the brain were thought to be associated with reproduction-things like attraction and sex behaviours.Then an explosion of research over the past decade revealed that a drop in oestrogen can have profound effects on memory,mood and even brain health in both men and women.
These findings raised a red flag with Brinton,who has been trying to understand why women are more susceptible to Alzheimer's disease. "I realised it might be the hormonal transition in perimenopause and menopause that appears to be the kick-starter for Alzheimer's in some women," she says.This idea also fit with findings from Brinton and others that oestrogen has a protective function on the brain.One form of oestrogen called,oestradiol,for example,ramps up activity in the brain cells' mitochondria-essentially,their energy factories.The extra energy boost helps cells recover from damage associated with the normal wear-and-tear of ageing.
"You can imagine that if there is this drop in oestrogen,the brain becomes more sensitive to damage,and that could lead to the death of neurons," says neuroscientist Amandine Grimm at the University of queensLand in Australia,who studies the ageing brain.And a fall in oestrogen levels doesn't just cause the brain to produce less energy,it also seems to change the type of energy it uses.
For most of our lives,the brain's fuel of choice is glucose."The brain is the most glucose-dependent organ in the body," says Brinton. At least,it is until menopause hits.Brinton has found that,as mice go through their equivalent of menopause,the amount of glucose metabolised by their brains drops dramatically,by about 25 per cent.
Hungry Brain: When body tissues are faced with a shortage of glucose,they enter a "starvation response,"and turn to fats as a backup source of energy.Something similar seems to happen in the brain.Over time,it appears that the brain resorts to a readily available source of fats-myelin,the fatty white sheaths that coat the majority of brain cells and ensure that brain signals travel quickly."We have found that the brain will catabolise the white matter for fuel," says Brinton.In short,the brain starts to eat itself.
Most of Brinton's research has been in mice,but in work yet to be published,she and her colleagues have tentative results suggesting that something similar happens in the brains of some women going through the menopause."We see that there is a decline in glucose metabolism,a change in white matter volume and grey matter volume,and an increase in beta amyloid production relative to men," she says.
Although most women with Alzheimer's are diagnosed in their 70s,the disease starts to develop 15 to 20 years before symptoms start to show-which is when the menopause occurs.So one should check every year or in between a six months gap, to take proper treatment to overcome Menopause linked Alzheimer's.