By 2050, About 135 million people There can be people living with dementia world wide. The most typical explanation for dementia is Alzheimer's disease. Women usually tend to develop Alzheimer's disease than men, at the same time as women live longer.
Symptoms of Alzheimer's disease normally appear after the age of 65. However, changes within the brain begin many years before symptoms begin. For women, this normally coincides with their transition into menopause.
Menopause ends in a decrease within the body's production of two hormones produced by the ovaries: estrogen and progesterone. These hormonal changes are related to a big selection of symptoms, including hot flushes, night sweats, difficulty sleeping, decreased libido, mood swings and brain fog.
Menopausal hormonal therapy (also called hormone substitute therapy or HRT), including estrogen alone or estrogen combined with progesterone, has been really helpful for many years to assist with menopausal symptoms.
But how does menopausal hormone therapy affect the danger of dementia? And why do some studies say therapy increases risk, while others say it decreases it?
Hormones and the brain
A big body of preclinical (animal-based) research shows that estrogen helps protect the brain. It reduces any damage to nerve cells and supports overall brain health.
Receptors that reply to estrogen are positioned in areas of the brain related to reproductive functions. But also they are inside. Regions of the brain Important for learning, memory and higher-level cognitive skills resembling planning, organization and decision-making.
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Loss of estrogen's “neuroprotective” effects after menopause contributes to a better incidence of Alzheimer's disease in women than in men.
Clinical studies They have also shown that girls who’ve undergone medical or surgical menopause before the age of natural menopause have a better lifetime risk of dementia and cognitive impairment.
This risk It starts to decrease In women who take estrogen therapy after their surgery.
This led researchers to hypothesize that adding estrogen back in—through menopausal hormone therapy—might protect and maintain women's cognitive health.
However, research findings haven’t been consistent.
Can menopausal hormone therapy affect dementia risk?
Concern concerning the risk of dementia and menopausal hormone therapy stems partially from the unexpected results of a landmark study conducted greater than 20 years ago.
gave The results showed Use of hormone therapy after menopause was related to an increased risk of dementia in women age 65 and older.
However, these studies have some vital limitations:
1) Most women were older than 65 years and greater than ten years postmenopausal.
2) The use of estrogen and progestogen type (an artificial type of progesterone) can have less profit on mental health.
Recently published Systematic reviews and meta-analyses The scientific data linking hormone therapy to the danger of Alzheimer's disease includes the outcomes of 51 different reports published through 2023.
The results showed that if hormone therapy was began in midlife, or generally inside ten years of the last menstrual period, the danger of Alzheimer's later in life was lower than in women who didn’t use hormone therapy. do
The largest reduction in risk was related to estrogen-only hormone therapy.
In contrast, when considering using hormone therapy later in life, or greater than ten years after menopause, estrogen-only therapy had neutral effects on Alzheimer's disease risk.
However, estrogen-progestogen therapy was related to an increased risk.
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only A clinical trial This meta-analysis has since been published. This study examined the long-term effects of using menopausal hormone therapy starting in early menopause.
The average age of the ladies was 52.8 years and 1.5 years postmenopausal once they entered the trial. They were randomly assigned to estrogen (with or without progestogen) or placebo for 4 years.
The researchers followed 275 women for ten years. They found no cognitive effects (no harm or no profit) based on whether the ladies received 48 months of hormone therapy or placebo.
What affects your risk?
The effects of menopausal hormone therapy on dementia risk look like influenced by several aspects. These include when someone starts taking it, how long they take it, the form of hormones used, and the person's genetic and health background.
1. When Therapy Begins: The Critical Window Hypothesis
An vital consider determining the effect of menopausal hormone therapy on cognitive function and risk of dementia appears to be when therapy begins relative to menopause. This is named the “critical window hypothesis”.
According to this hypothesis, estrogen may help protect neurons within the brain provided that it begins early within the menopausal transition, especially inside a number of years of menopause, when the brain remains to be more aware of hormones. could also be
2. Type of menopausal hormone therapy and the role of progesterone
Types of hormones involved in hormone therapy Widely different of their molecular structure in addition to their physiological functions.
Different varieties of estrogen (resembling estradiol or conjugated estrogens) and the inclusion of progestogens (required for girls who haven’t had a hysterectomy) can have different effects on mental health and dementia risk.
Some studies suggest that adding a progestogen to estrogen therapy may counteract a number of the cognitive advantages of estrogen alone, possibly by blocking estrogen receptors within the brain.
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3. Role of vasomotor symptoms
Vasomotor symptoms, resembling hot flushes and night sweats, are signs of menopause. More vasomotor symptoms are experienced Linked to weak memory As well as one Increase in biological markers Linked to risk of dementia.
Therefore, one potential pathway by which menopausal hormone therapy may moderate the danger of Alzheimer's disease is thru their effects on reducing vasomotor symptoms.
4. An individual's genetic and health background
The best genetic risk for early-onset Alzheimer's disease is carrying a number of copies of a particular version of the APOE gene, called APOE e4.
There is one The emerging hypothesis That women who’ve this genetic risk for Alzheimer's disease may show the best profit from using hormone therapy.
What does this mean for you?
The medical and scientific community remains to be debating whether menopausal hormone therapy may play a job in the danger of Alzheimer's disease.
Overall, the choice to make use of hormone therapy must be individualized, making an allowance for your age and timing of menopause, health status, and specific menopausal symptoms.
We need more research before we will make firm decisions concerning the role of hormone therapy and the danger of dementia, but based on current evidence, hormone therapy could also be helpful if began early within the menopausal transition, especially For women with a genetic risk of Alzheimer's disease.