エストロゲン単独療法がアルツハイマー病指標減少と関連 (Estrogen-Only Therapy Linked to Fewer Alzheimer’s Hallmarks)

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2026-08-12 スタンフォード大学

スタンフォード大学医学部の研究チームは、更年期ホルモン療法(MHT)のうちエストロゲン単独療法がアルツハイマー病リスクに与える影響を解析し、その効果が治療開始時期や患者背景によって異なる可能性を示した。研究では、女性におけるアルツハイマー病リスク上昇の要因として、閉経後のエストロゲン低下が脳機能や神経保護作用に影響することに着目した。特に、閉経後早期に開始されるエストロゲン補充は認知機能維持に有益である可能性が示唆される一方、高齢になってから開始した場合には明確な予防効果が確認されていない。研究者らは、ホルモン療法を認知症予防目的だけで使用すべきではないとしつつも、女性特有のアルツハイマー病リスクを理解するうえでエストロゲンの役割が重要であると指摘している。また、APOE4遺伝子などの遺伝的要因との関連についても研究が進められており、将来的な個別化予防戦略への応用が期待される。

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更年期ホルモン療法とアルツハイマー病の神経病理との関連性 Association Between Menopausal Hormone Therapy and Alzheimer Disease Neuropathology

Jennifer Bruno, Jacob S. Shaw, and S.M. Hadi Hosseini for Alzheimer’s Disease Neuroimaging Initiative
Neurology  Published:August 12, 2026
DOI:https://doi.org/10.1212/WNL.0000000000218413

Abstract

Background and Objectives
Although evidence suggests that the neurophysiologic impact of estrogen decline during menopause may contribute to increased risk of Alzheimer disease (AD) in women, the effect of menopausal hormonal therapy (MHT) on AD risk requires further study. We sought to examine the associations between MHT use and neuropathologic, clinical, and imaging/fluid biomarker outcomes.

Methods
In this cohort study, we tested the association between estrogen-only MHT use and dementia outcomes in female participants using 2 independent, large-scale data sets: National Alzheimer’s Coordinating Center (NACC) and Alzheimer’s Disease Neuroimaging Initiative (ADNI). Participants included women 50 years and older with self-reported use of estrogen-only MHT or no self-reported use of MHT. Clinical, imaging/fluid biomarker, and neuropathologic outcomes were examined. Research was performed at academic medical centers.

Results
Neuropathologic data were collected from NACC for 258 MHT users (mean age of death = 81.9, SD = 19.5) and 2,701 non-MHT users (mean age of death = 82.2, SD = 11.0). The ADNI cohort included 110 MHT users (mean age = 76.5, SD = 7.5) and 1,948 non-MHT users (mean age = 73.2, SD = 8.9). The odds of increased AD pathology on autopsy (primary outcome) were significantly decreased in MHT users relative to nonusers (odds ratio [OR] 0.65, 95% CI 0.48–0.88, p = 0.005). MHT use was associated with secondary outcomes including significantly decreased amyloid pathologic load assessed through plasma (β = 0.44, 95% CI 0.16–0.73, p = 0.0025) and CSF (β = 0.07, 95% CI 0.002–0.13, p = 0.030). MHT use was associated with significantly lower odds of clinical dementia diagnoses (OR 0.61, 95% CI 0.55–0.67, p < 0.0001) and lower odds of symptoms of memory/functional decline (OR 0.67, 95% CI 0.61–0.74, p < 0.0001).

Discussion
Our findings demonstrate small but significant associations between MHT use during later life and a range of AD-related neuropathologic and clinical outcomes in 2 large cohorts of female participants. Although our results do not address causality and have limited generalizability due to the retrospective nature of the study, they suggest a protective effect of MHT use in the dementia course.

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