Associations of estrogen with modifiable and non-modifiable risk factors for dementia: A narrative review

Female sex is associated with higher incidence and risk of dementia. Estrogen may represent one important mechanism contributing to the increase in incidence rates. In this review, we synthesize narratively the evidence for associations between estrogen-across the life course from menarche to menopause, estrogen-containing hormonal contraception and hormone replacement therapies, and pregnancy-with potential modifiable risk factors for dementia. These include education, hearing loss, traumatic brain injury, hypertension, alcohol use, obesity, smoking, depression, physical inactivity, diabetes, low-density lipoprotein (LDL) cholesterol, social isolation, air pollution, and untreated visual loss, as well as apolipoprotein E ε4. In addition, evidence is summarized for associations with sleep, diet, and stress. Evidence suggests that estrogen is associated with some of these modifiable risk factors for dementia, particularly LDL cholesterol, smoking, and depression. Research needs to further define these associations and understand whether interventions targeting estrogen levels at key life stages could offer intervention opportunities to reduce future risk of dementia in women. HIGHLIGHTS: Higher dementia risk in women may be associated with estrogen. Estrogen is associated with some of the modifiable risk factors for dementia. However, significant gaps exist in the literature for most risk factors.