Hormone therapy is widely used to treat menopausal symptoms reminiscent of hot flushes and night sweats. But scientists have long debated whether it affects dementia risk.
A new study Adds one other piece to the puzzle. This suggests that an Alzheimer's biomarker could help discover which women are at higher risk of dementia with specific hormone treatments.
Researchers analyzed blood samples from 2,766 women recruited into the clinical trial from 1996 to 1999. They then followed the participants until 2021 to look at whether plasma p-tau217 levels at first of the study were related to individuals with dementia, and whether the association relied on treatment.
Plasma p-tau217 is a biomarker. For Alzheimer's disease, a measurable biological indicator of the condition. High levels within the blood are linked to brain changes related to Alzheimer's.
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The study compared women who received one or two placebos. Types of hormone therapy. A mixture hormone therapy that accommodates estrogen and progesterone is often prescribed for girls who still have ovaries. The other was estrogen-only therapy, which is often given after a hysterectomy.
Women with higher levels of Alzheimer's biomarkers have a significantly higher risk of developing dementia. In the study's principal evaluation, higher baseline p-tau217 levels were related to a virtually threefold increased risk.
However, the connection differed depending on the style of hormone therapy used. Among women assigned to combined hormone therapy, higher levels of the biomarker were related to a virtually fourfold risk of dementia. This pattern was not seen in women using only estrogen therapy.
The association was strongest in certain groups, including women over age 70, white women and other people with the APOE4 genotype, a genetic variant. Increases a person's risk the event of Alzheimer's disease.
Scientists believe. Differences between treatments could also be related to how hormones interact with Alzheimer's biology. Estrogen may help protect brain cells and affect how the brain processes the amyloid and tau proteins that accumulate in Alzheimer's disease. Progesterone can reverse these effects in these ways. Not fully understood yet.
Colleagues and me First It found that carriers of this genetic risk factor who used hormone therapy also had worse dementia-related biomarkers than those that didn't use hormones or had no genetic risk.
First evidence
The data for the brand new evaluation got here from Women's Health Initiative study, a big program of clinical trials examining the long-term health effects of hormone therapy.
One component of this program, the Women's Health Initiative Memory Study, examined whether hormone therapy affects the danger of dementia. gave A 2003 study Combined hormone therapy was found to just about double the danger of dementia in women age 65 and older. A trial of intensive hormone therapy followed. Stopped first More than planned because the general risks, including breast cancer, stroke and blood clots, outweigh the advantages.
These findings apply to women who began hormone therapy after age 65. At the time, hormone therapy was often prescribed. Long term to prevent conditions reminiscent of osteoporosis. Today it normally starts earlier, around menopause, which is around age 50.
After these results were published, Many women stop taking hormone therapy.including near menopause.
Later research suggested a more nuanced picture. Follow-up analyzes of ladies who began hormone therapy between the ages of fifty and 54 found no evidence that treatment affected cognitive function when assessed six to seven years after the trial ended.
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Similar results have been reported. reported in other clinical trials. of relatively healthy women who began hormone therapy near menopause; These studies show that combined hormone therapy for as much as ten years appears to be generally secure but doesn't provide measurable cognitive advantages.
When hormone therapy is began later in life, the image looks different.
Different outcomes in older women
Among women who began hormone therapy after age 65 within the Women's Health Initiative Studies, overall cognitive performance declined when tested around age 70.
Further evidence emerged from 2010 Analysis From the identical group of ladies. Eight years after joining the study, MRI scans showed a trend toward smaller volumes within the hippocampus and frontal lobes in older women using combined hormone therapy.
Shrinkage in the hippocampus is often seen in Alzheimer's disease and should indicate that combined hormone therapy may worsen existing cognitive impairment in some older women.
New discoveries.
The latest evaluation adds further evidence and is consistent with my colleagues' and my meta-analyses of national registry data showing an increased risk of Alzheimer's in older women using combination hormone therapy but not estrogen alone. A small increase was also seen in postmenopausal women when treatment continued for greater than five years.
Menopausal symptoms themselves can also play a job. Severe hot flushes and night sweats have been linked to an increased risk. Dementia When they're in later life. Women with these symptoms are also more more likely to be on hormone therapy, making it difficult to separate the consequences of symptoms from treatment.
Symptom severity can be related to other risk aspects for dementia, including: Smoking and obesitythe poor to sleepand Stress and alcohol use.
What does this mean for girls?
Importantly, this study doesn't show that hormone therapy itself causes dementia. Instead, it suggests that biological risk markers may help discover women who could also be more vulnerable when treatment begins later in life.
Overall, the connection between hormone therapy and dementia risk will depend on when treatment is began, whether someone already has risk aspects, and the way long the therapy is used.
Starting combined hormone therapy later in life, especially after age 65, may increase the danger of cognitive decline in some women. But studies haven't generally found the identical risks when treatment is began around menopause and used for a shorter time frame.
Taking hormone therapy for five years or less when starting around menopause is just not related to cognitive decline or Alzheimer's disease. Clinical trials Or at most National Registry Study.
Because most girls use hormone therapy for a limited time to administer menopausal symptoms, the danger of dementia is unlikely to extend when it begins during menopause.