An analysis of more than 800,000 women in Denmark offers more insight into the murky links between female hormones and midlife mental illness in women: It hints that hormone therapy (HT) may boost the risk of depression, have no effect, or lower it – all depending on how it’s administered and when.
Women who took systemic HT had a higher risk of depression from age 48 to 50 (adjusted hazard ratio, 1.50; 95% confidence interval, 1.24-1.81), researchers reported in JAMA Network Open. However, there was no overall link between depression and locally administered HT (aHR, 1.15; 95% CI, 0.70-1.87) – except when HT was begun between ages 54 and 60, when there were signs of a protective effect (aHR, 0.80; 95% CI, 0.70-0.91).
“Women in menopause who initiate systemically administered HT should be aware of depression as a potential adverse effect,” epidemiologist and study corresponding author Merete Osler, MD, PhD, DMSc, of Bispebjerg and Frederiksberg (Denmark) Hospitals and the University of Copenhagen, said in an interview. ”Further, women and clinicians alike should be aware of any misinterpretation of symptoms of depression as menopausal disturbances.”
Dr. Osler said the researchers launched the study to better understand potential hormone-depression links in light of suspicions that lower levels of estrogen in menopause may contribute to depression.
Several randomized clinical trials and cohort and cross-sectional studies have explored whether systemic HT affects depression during menopause, Dr. Osler said, “but the results from these studies have been inconsistent, and few have explored the role of the route of administration.”
For the new registry-based study, researchers retrospectively tracked all women in Denmark who were aged 45 between 1995 and 2017 without prior oophorectomy, certain kinds of cancer, prior use of HT, or ongoing depression.
During follow-up to a mean age of 56, 23% of the women began HT (at a median age of 55), and 1.6% were hospitalized for depression. Of those on HT, 65.8% received locally administered HT.
Researchers adjusted hazard ratios for a long list of factors such as educational level, marital status, number of still births or live births, prior use of hormonal contraceptives, several medical conditions, and prior depression.
“We were surprised by our findings, which to some degree contradicted our prior hypothesis that systemic HT with estrogen would not be associated with first-time depression diagnosis in women aged 45 and above, while HT with progesterone would be associated with a slightly increased risk,” Dr. Osler said. “In our study, systemically administered HT was associated with an increased risk of depression with no difference between estrogen alone or in combination with progestin. As findings from previous studies have been inconsistent, our findings fit with some but not all previous studies.”
Why might the mode of administration make a difference? It’s possible that local administration may contribute less to the systemic circulation, Dr. Osler said, “or that menopausal symptoms including depression are more likely to be treated with systemic HT.”
As for age differences, Dr. Osler said “it is possible that women are more sensitive to the influence of HT on mood around menopause than at later ages. However, it should be noted that in the present study it was not possible to calculate precise risk estimates for use of systemic HT in menopausal women above age 54 because less than 1% initiated treatment with systemic HT after age 54 years.”
In an interview, psychiatrist Natalie Rasgon, MD, PhD, of Stanford (Calif.) University, who’s studied hormones and depression, said the study is “remarkably large and consistently executed.”
She cautioned, however, that the findings don’t prove any causality. “Saying that estrogen therapy or hormone therapy causes depression is patently incorrect.”
How can the findings be useful for medical professionals? “Women and physicians alike need to be very mindful of pre-existing mood disorders,” Dr. Rasgon said. “Women who in the past had anxiety disorders, mood swings, PTSD, or prior episodes of depression might have a differential response to hormone therapy in menopause.”
Also keep in mind, she said, that the transition from menopause to post menopause is “very volatile,” and depression may break through even in women undergoing treatment for the condition.
For her part, Dr. Osler said this study and others “emphasize the need for clinical guidelines to further consider the psychological side effects of systemic HT.”
Funding information was not provided. The study authors and Dr. Rasgon have no disclosures.