Alzheimer’s disease is the most common type of dementia. In 2020 there were over 55 million people worldwide living with dementia and by 2050 it is supposed to reach 139 million worldwide, with most of them being in developing countries.
Of dementia disorders, Alzheimer’s is supposed to be the most common type of dementia and presently about 7.6 million people in India are supposed to be affected by it.
Alzheimer’s is a progressing disease causing problems with memory, thinking and behaviour.
The fact that Alzheimer’s affects elderly women more than elderly men is a known fact. However, why is it so has been a mystery and scientists have been working towards finding the reason.
Recently a finding has been made by scientists at the Scripps Research Institute and Massachusetts Institute of Technology (MIT) in the US.
According to the study of the post-mortem results of men and women who died of Alzheimer, it was found that a chemically modified form of an inflammatory immune protein called complement C3, is found in much greater quantity in women than in men. This protein C3 is known to increase Alzheimer’s.
While studying biochemical and molecular events underlying neurodegenerative diseases it was found that C3 is formed in a process called protein S-nitrosylation.
The researchers had previously discovered this chemical reaction, which happens when a nitric oxide (NO)-related molecule binds tightly to a sulphur atom (S), on a particular amino acid building-block of proteins to form a modified “SNO-protein”.
Though tiny protein modifications are common which affect brain function but large scale modifications are considered to be a key contributor to Alzheimer’s and other neurodegenerative disorders.
Researchers tried to quantify the proteins modified in 40 post-mortem human brains. Half of the brains were from people who had died of Alzheimer’s, and half were from people who hadn’t.
In these brains, the scientists found 1,449 different proteins that had been S-nitrosylated.
Strangely it was also found that the levels of S-nitrosylated C3 (SNO-C3) were more than six-fold higher in female Alzheimer’s brains compared to male Alzheimer’s brains.
Scientists have known for more than 30 years that Alzheimer’s brains have higher levels of complement proteins and other markers of inflammation, compared to neurologically normal brains.
The complement proteins are known to trigger immune cells in the brain called microglia which destroy synapses.
The synapse-destroying mechanism is supposed to be at the heart of the Alzheimer’s disease process.
Synapse being the key for messaging in brain, its loss is closely related to cognitive decline in Alzheimer’s brains.
As far as women are concerned it was also noticed that oestrogen specifically protects women’s brains from C3 S-nitrosylation. However, as woman ages and reaches menopause there is a fall in oestrogen and she is no longer protected from a possible attack of Alzheimer’s.
The SNO-C3 increases as estrogen levels fall, due to the activation of an enzyme that makes NO in brain cells. This increase in SNO-C3 activates microglial destruction of synapses.
There is thus an increased vulnerability of women as they age.
So the chances of developing Alzheimer’s disease late in life are somewhat greater if you are a woman than a man.
Another explanation for women being more prone to Alzheimer’s as they age was because they lived longer than men and build up amyloid plaques (abnormal proteins that form in the spaces between nerve cells in the brain) thought to play a central role in Alzheimer’s disease. The amyloid plaques first develop in the areas of the brain concerned with memory and other cognitive functions.
The amyloid plaques that cause Alzheimer’s disease are supposed to be part of the brain’s immune system to fight against infections. As women have stronger immune systems than men they are likely to be more affected by the plaques.
Women are almost twice as likely as men to develop Alzheimer’s.
The increased prevalence of Alzheimer’s among women likely arises through a combination of factors, including sex chromosomes, hormones, brain structure, and gender and life experiences.
Interestingly, androgens (i.e., male sex hormones, including testosterone) are neuroprotective in late life and may help preserve brain health and function in men, leading to lower levels of disease.
Alzheimer’s is also affected by social and lifestyle factors including education, occupation, social activities, diet, and exercise.
Women can lower the risk of Alzheimer’s by focusing on the lifestyle factors under their control like eating a varied, nutritious, and low-glycaemic diet. Include foods that contain vitamins C, D, and E, omega-3 fats, and antioxidants.
Do regular exercise and maintain a healthy weight. Sleep well. Keep the mind active. Play memory games.
Take good care of health to avoid diseases which increased risk of Alzheimer’s disease like diabetes, heart disease, traumatic brain injury (concussions), depression, etc.
| Posted by Sameer Khan | 
