Using hormone replacement therapy (HRT) to ease the effects of menopause increases the risk of dementia, but the link may not depend on the treatment, a new study finds.
The national Danish study, published in the BMJ, appears to contradict some earlier research showing that hormone replacement therapy Cognitive decline can be prevented if treatment is started at the onset of menopause.
But the situation is complicated by scientists’ inability to distinguish the original cause of hormone replacement therapy (which treats changes in sleep, mood, memory and thinking) from the early symptoms of dementia.
So, in some of the women in the study who were treated with hormone replacement therapy, the symptoms that prompted treatment may actually reflect earlier neurological changes that would have led to a dementia diagnosis anyway.
Dr Sarah-Naomi James of the MRC Lifelong Health and Aging Unit at University College London, who was not involved in the Danish study, said the reasons for HRT prescribing were similar to early symptoms of dementia.
“This new research alone should not change practice,” Dr James said in a statement.
For the study, researchers followed more than 60,000 Danish women, 5,589 of whom had dementia.
Of the nearly 18,000 people who received HRT with a combination of estrogen and progestin, half started treatment before age 53 and half stopped treatment within four years. About 90 percent use oral medications.
Compared with women who never used HRT, women who used HRT had a 24 percent higher risk of eventually being diagnosed with dementia.
This risk increased with duration of treatment, reaching 74% for those who had received HRT for more than 12 years.
About 15% of women aged 45 to 64 in England are currently receiving HRT, according to the Department of Health.
The link between HRT and dementia
Hormone replacement therapy (HRT) was widely used until 2003, when a large randomized trial found that it was associated with a two-fold increased risk of dementia in women over 65.
But subsequent studies found no increase in HRT initiated between the ages of 50 and 55 or shortly after menopause.
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But in the new study, the link between HRT use and dementia remained regardless of when treatment was started.
“The observed association is likely artifactual and should not be used to infer a causal relationship between hormone therapy and dementia risk,” the study authors said, nor should it be used to help physicians and patients make decisions about the use of hormone replacement therapy .
Study leader Dr Amani Meaidi, of the Danish Cancer Society Research Center in Copenhagen, said that while the study could not prove that HRT caused dementia, a causal relationship was “biologically plausible” and further research was needed.
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Benefits of Hormone Replacement Therapy
Meanwhile, because of the well-known side effects of hormone replacement therapy, including an increased risk of cancer and blood clots, Danish experts recommend that women with menopausal symptoms first try lifestyle interventions such as exercising, minimizing alcohol and caffeine intake, avoiding Smoking and maintaining a healthy weight, Dr. Meady said.
If lifestyle changes aren’t helping, and there’s no medical reason to avoid hormone replacement therapy, doctors recommend that doctors prescribe hormone therapy for the shortest duration and lowest dose possible, she said.
The menopause charity says body-aligned hormone replacement therapy has been shown to help reduce women’s long-term risk of osteoporosis, heart disease and even colon cancer.
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Other studies in the US found that “women who took the same transdermal estrogen and progesterone they used in their bodies were 73% less likely to develop dementia and other degenerative brain diseases”.
The charity called it an “amazing and heartening figure” because two-thirds of people with Alzheimer’s are women.