Estrogen therapy increased the risk of dementia

Hormone therapy after hysterectomy using estrogen alone increases the risk of dementia. The likelihood of Alzheimer's disease was found to be the highest.

Researchers from the University of Copenhagen and the Danish Cancer Institute evaluated the effect of estrogen replacement therapy after hysterectomy on the risk of dementia. The results of the study are published in the journal JAMA Network.

They found a 1.55-fold increase in the risk of dementia among women who received estrogen-only therapy compared to participants who did not receive estrogen. This increased risk was observed only until participants reached age 55 years. The risk of developing Alzheimer's disease increased more, by a factor of almost 1.8.

The most pronounced increase in risk was associated with taking medications for more than 5 years, a higher daily dose of estrogen, and oral estradiol intake.

Data from 29,104 women who had undergone hysterectomy, aged 50-60 years, without prior dementia, ovariectomy, or contraindications to hormone replacement therapy in menopause were analyzed.

Participants were divided into subgroups according to age, duration of estrogen use, and average daily dose. The follow-up period was 18 years. The frequency of first-time diagnosis of dementia of any etiology or prescription of dementia medications was assessed. Comparisons were made with peers in the control group who had never received hormone therapy.

During the follow-up period, dementia was registered in 541 women, with Alzheimer's disease diagnosed in 92 participants. The average age at the time of diagnosis was 70 years. Estrogen therapy alone was given to 53.2% of participants with dementia and 45% of participants in the control group.

The mean age at the time of treatment initiation was 53 years. The mean duration of estrogen therapy was 5.4 years in the dementia group. Of the estrogens, estradiol was the most commonly used (94%): 81% as tablets and 19% as patches.