Women on hormone replacement therapy may face an increased risk of developing Alzheimer’s disease, according to the findings of a new study.
Researchers from Finland indicate that while the overall risk was low, hormone replacement therapy increased women’s risk of Alzheimer’s, especially when they used combination drugs.
In a study published earlier this month in the medical journal BMJ, researchers evaluated data from Finland between 1999 and 2013, including more than 85,000 postmenopausal women who were diagnosed with Alzheimer’s disease. These findings were compared to 85,000 women without Alzheimer’s.
Women who had Alzheimer’s disease were more likely to have been on hormone replacement therapy. The risk was more prominent among women who had been on hormone replacement therapy for more than 10 years.
When hormone replacement therapy, especially estrogen-progestogen therapy, was started by women younger than 60 years old, the risk increased eight percent to 17%. However, women who started the therapy after 60 also had an increased risk of the disease.
Researchers noted the risk was higher for women using estrogen-progestogen therapy compared to estradiol only therapy. Using vaginal estradiol therapy only did not increase the risk of Alzheimer’s.
The risk was also not increased based on the type of combination estrogen-progestogen therapy. Any type, including norethisterone acetate, medroxyprogesterone acetate, and other estrogen-progestogen combinations, carried the same risk.
Nearly two-thirds of the six million people diagnosed with Alzheimer’s in the U.S. are female. Similarly, the number of women with dementia also largely outweighs the number of men with the disease. Women are disproportionately affected by neurodegenerative diseases and researchers think hormones may be one of the risk factors.
Other studies have also pointed to an increased risk of Alzheimer’s from hormone replacement therapy. Results of the Women’s Health Initiative Study linked hormone replacement therapy to increased risk of not only dementia, but also heart disease, stroke, and breast cancer.
The study did not indicate a cause and effect relationship between hormone replacement therapy and Alzheimer’s. Instead, it indicated a link between the two which warrants further study.
Nevertheless, researchers emphasized, the absolute increased risk of Alzheimer’s is small. However, it is important for the data to be shared and provided as information to current and future users of hormone therapy so they can make informed decisions weighing both the benefits and the risks.