Early menopause increases a woman's risk for dementia, study suggests

Early menopause – when a woman's menstrual cycle ends by age 45 – increases the risk of dementia by 35%, a new study finds.

Researchers also found that women who enter menopause early are more likely to be diagnosed with early dementia, which occurs before age 65.

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Low estrogen levels may be one of the reasons for this increased risk, researchers said. The lack of estrogen increases oxidative stress – an imbalance of antioxidants and free radicals in the body – which has been linked to accelerated brain aging and cognitive impairment.

Estrogen can activate antioxidants, reduce a common genetic risk factor for dementia and diminish amyloid plaque in the brain, researcher Wenting Hao told U.S. News and World Report. The build-up of amyloid plaque is one of the features of Alzheimer's disease, the most common form of dementia. 

"It's a red flag on many levels when a woman goes through premature menopause, as it indicates there may be some underlying genetic, environmental or health behavior issues that we really need to focus on," Dr. Donald Lloyd-Jones, president of the American Heart Association told CNN.

Jones, who was not involved with the study, added that "the scope and breadth of the data is important and impressive, but it doesn't give us the details we need to understand the study's full implications."

The average woman enters menopause at 52, according to the federal Office on Women's Health. 

Women who become menopausal before age 40 are considered to be in premature menopause. Early menopause occurs when menstruation stops between ages 40-45. 

Both conditions can be caused by genetics, autoimmune disorders, smoking, chemotherapy or pelvic radiation, and surgery to remove the ovaries and uterus.

Common symptoms of the menopause transition include vaginal dryness, hot flashes, trouble sleeping, night sweats, mood changes, weight gain, dry skin and thinning hair.

Some women take hormone replacement therapy to treat the symptoms, but studies have linked it to an increased risk for heart disease, stroke, breast cancer and blood clots.

There are ways beyond estrogen therapy that can help women in early menopause reduce their risk of cognitive decline, researchers said. Regular exercise, engaging in activities that stimulate the brain and practicing a healthy lifestyle – maintaining a healthy weight and not smoking or drinking alcohol – can all help.

Researchers said women in early menopause should work closely with their health care providers to monitor their cognitive function as they age.