Women who experience menopause at an earlier age face a higher likelihood of developing Alzheimer's disease sooner, according to new research.
Those entering menopause in their early 40s may exhibit symptoms of the disease almost two years earlier than other patients. The study, published in JAMA Neurology, also found that menopause around age 45 is associated with a 15% increase in dementia-related brain damage compared to those who experience it five years later.
Researchers from the University of California San Francisco suggest that estrogen, a sex hormone that significantly declines during menopause, plays a protective role against cognitive decline. The age of menopause onset could potentially serve as an early indicator for Alzheimer's disease, even before noticeable cognitive changes occur.
The study analyzed data from over 2,600 U.S. women, with an average age of 78. Approximately two-thirds experienced natural menopause, while the remainder underwent surgical menopause, often due to ovary removal. Participants reported the age they began menopause, with the average being 49.
Brain scans conducted on hundreds of participants revealed that earlier menopause was associated with poorer cognitive outcomes, a younger age of Alzheimer's onset, and more rapid brain shrinkage later in life. Women who underwent natural menopause around age 45 showed an estimated 15% more age-related brain damage over a decade compared to those who started menopause at age 50. This damage primarily affected white matter, crucial for communication between brain cells.
Overall, the researchers estimated that women experiencing menopause 10 years earlier than the average age of 49 had approximately 1.8 fewer years without an Alzheimer's diagnosis compared to those whose menopause occurred a decade later. Early menopause was also linked to a faster decline in episodic memory, which involves recalling events and experiences.
Surgical menopause demonstrated a stronger correlation with Alzheimer's risk and memory decline, while earlier natural menopause was more closely linked to signs of brain aging observed in scans. Researchers theorize that the abrupt and significant drop in hormone levels following the removal of both ovaries in surgical menopause may contribute to these stronger associations.
Estrogen is believed to support brain health by facilitating communication between brain cells, maintaining the protective myelin sheath around nerves, and reducing inflammation. However, the researchers emphasized that these findings do not guarantee that all women experiencing early menopause will develop Alzheimer's. Instead, they advise that individuals who go through menopause early should take steps to mitigate their risk.
While Alzheimer's is the most common type of dementia, women constitute about two-thirds of the estimated 982,000 individuals living with dementia in the UK. While the reasons for this higher susceptibility are not fully understood, hormones are considered a potential factor.
Steps individuals can take to reduce dementia risk include regular exercise, avoiding smoking, and limiting alcohol consumption. For those concerned about themselves or a loved one, consulting a general practitioner is recommended.