Use of menopausal hormone therapy is associated with increased risk of dementia in a nationwide, nested case-control study conducted in Denmark. The relationship held even in women who received treatment at the age of 55 years or younger. “The increased rate of dementia was similar between continuous and cyclic treatment,” write the authors. “Further studies are warranted to determine whether these findings represent an actual effect of menopausal hormone therapy on dementia risk, or whether they reflect an underlying predisposition in women in need of these treatments.”
Risks of a first-time diagnosis of all-cause dementia in 5,589 incident cases of dementia and 55,890 age-matched controls between 2000 and 2018 from a population of all Danish women aged 50-60 years in 2000 with no history of dementia or contraindications for use of menopausal hormone therapy were as follows: “Compared with people who had never used treatment, people who had received oestrogen-progestin therapy had an increased rate of all cause dementia (hazard ratio 1.24 (95% confidence interval 1.17 to 1.33)). Increasing durations of use yielded higher hazard ratios, ranging from 1.21 (1.09 to 1.35) for one year or less of use to 1.74 (1.45 to 2.10) for more than 12 years of use. Oestrogen-progestin therapy was positively associated with development of dementia for both continuous (1.31 (1.18 to 1.46)) and cyclic (1.24 (1.13 to 1.35)) regimens. Associations persisted in women who received treatment at the age 55 years or younger (1.24 (1.11 to 1.40)). Findings persisted when restricted to late onset dementia (1.21 (1.12 to 1.30)) and Alzheimer’s disease (1.22 (1.07 to 1.39)).”