Age at Menopause and Lifetime Cognitive Functioning: Findings from a British Cohort Study

Age at Menopause and Lifetime Cognitive Functioning: Findings from a British Cohort Study

Research has suggested a relationship between the age at which a woman goes through menopause and her general cognitive functioning, specifically that better cognitive function is observed in women who enter into menopause at a later age, as compared to an earlier age. A recent study seeks to examine this relationship while adjusting for many of the factors known to be associated with cognitive function, such as early childhood cognitive function, level of education, socioeconomic status, smoking habits, and body mass index (BMI). This study also distinguishes between women who go through natural versus surgical menopause, and, if surgical, between women who had only oophorectomies versus those who also had hysterectomies.

Data for this analysis was extracted from a British cohort study known as the Medical Research Council National Survey of Health and Development (NSHD). Researchers used data from 1,315 of the women in this cohort pertaining to both the type of and age at menopause. The study also utilized data regarding women’s histories of hormone replace therapy (HRT) use, as HRT was predicted to be a potential covariable in the model. Information regarding the women’s early childhood cognitive functioning, level of education, occupational class, smoking habits, and BMI were analyzed as well. Occupational class referred to a pre-established spectrum of 6 categories as defined by the Registrar General—the categories ranged from “professional” to “unskilled manual.”

The study then examined data from multiple cognitive assessments of both the women’s verbal memory abilities and processing speeds across different time markers (ages 43, 53, 60-64, 69). The range of time markers allowed for the examination of both the pre- and post-menopausal verbal memory abilities and processing speeds of the women.

Looking solely at women who experienced natural menopause (n = 846), those who went through menopause at a later age had higher verbal memory scores than those who went through menopause at an earlier age (r = 0.17, p = 0.001). Even after adjusting for the other variables known to impact later cognitive abilities, higher verbal memory scores were significantly associated with later natural menopausal age (p = 0.013). This suggests that later natural menopausal age may serve as a buffer from cognitive decline, specifically in terms of women’s verbal memory.

There was a similar trend in the women who underwent surgical menopause (n = 313), regardless of the type of surgery that caused the menopause. Higher verbal memory abilities were associated with later ages at the time of surgery (r = 0.16, p = 0.002). However, this association was significantly weakened when level of education, occupational class, early childhood cognitive functioning, and BMI were controlled for (p = 0.2). Overall, among all variables examined in this study in addition to type of and age at menopause, verbal memory was found to be most closely associated with early childhood cognitive functioning, level of education, and occupational class.

Unlike verbal memory, processing speed did not seem to be associated with the age at which natural menopause occurred (r = 0.77, p = 0.2). Processing speed also seemed unrelated to the age at which surgical menopause occurred (r = 0.54, p = 0.4).

While this study was primarily focused on the relationship between age of menopause and cognitive functioning, it also provides interesting results regarding lifetime use of HRT in relation to cognitive abilities and function. Overall, within the general cohort of women with a history of HRT use, HRT use was not significantly correlated to either better verbal memory or processing speed at the time of, or after, menopause.

However, this study did find that specifically for women who underwent surgical menopause via bilateral oophorectomy, previous HRT was related to better processing speeds post-menopause and functioned as a protective factor. Though this study mostly offers support to the research that has shown that HRT has no significant beneficial impact on cognitive function in women regarding their verbal memory and processing speeds, this study’s specific finding about women who became menopausal as a result of bilateral oophorectomy offers an intriguing suggestion that HRT use could benefit a specific subset of women during menopause.

Considering that menopause, in terms of both its timing and its cause, does seem to play a role in cognition and cognitive decline, future research is warranted. Notably, this study also considered other factors that influence cognitive decline, such as level of education, occupational class, and childhood cognitive abilities. If childhood cognitive abilities are strongly related to cognitive decline later in life, such that better early childhood cognitive functioning is correlated to delayed cognitive decline, it seems imperative to consider ways to develop and promote strong cognitive development in childhood. Though commentary about encouraging development of early childhood cognitive abilities may seem tangential to this current article about menopause, it is none the less important, as all of these factors combined can determine the trajectory of woman’s cognitive decline. It will be interesting to see how future research will integrate this data to investigate the ways to extend or delay the age at which women experience menopause to utilize its protective factors against cognitive decline, considering the beneficial effects that later menopausal timing has on cognitive ability, particularly in terms of verbal memory.

 

Isabel Glass

 

Kuh, D., Cooper, R., Moore, A., Richards, M., & Hardy, R. (2018). Age at menopause and lifetime cognition: Findings from a British birth cohort study. Neurology, 90 (19), 1673-1681.

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