Women who breastfeed exhibit cognitive benefits after age 50

Abstract

Background and objectives: Women who breastfeed may experience long-term benefits for their health in addition to the more widely appreciated effects on the breastfed child. Breastfeeding may induce long-term effects on biopsychosocial systems implicated in brain health. Also, due to diminished breastfeeding in the postindustrial era, it is important to understand the lifespan implications of breastfeeding for surmising maternal phenotypes in our species' collective past. Here, we assess how women's breastfeeding history relates to postmenopausal cognitive performance.

Methodology: A convenience sample of Southern California women age 50+ was recruited via two clinical trials, completed a comprehensive neuropsychological test battery and answered a questionnaire about reproductive life history. General linear models examined whether cognitive domain scores were associated with breastfeeding in depressed and non-depressed women, controlling for age, education and ethnicity.

Results: Women who breastfed exhibited superior performance in the domains of Learning, Delayed Recall, Executive Functioning and Processing Speed compared to women who did not breastfeed (P-values 0.0003-0.015). These four domains remained significant in analyses limited to non-depressed and parous subsets of the cohort. Among those depressed, only Executive Functioning and Processing Speed were positively associated with breastfeeding.

Conclusions and implications: We add to the growing list of lifespan health correlates of breastfeeding for women's health, such as the lower risk of type-2 diabetes, cardiovascular disease and breast cancer. We surmise that women's postmenopausal cognitive competence may have been greater in past environments in which breastfeeding was more prevalent, bolstering the possibility that postmenopausal longevity may have been adaptive across human evolutionary history.

Lay summary: Breastfeeding may affect women's cognitive performance. Breastfeeding's biological effects and psychosocial effects, such as improved stress regulation, could exert long-term benefits for the mother's brain. We found that women who breastfed performed better on a series of cognitive tests in later life compared to women who did not breastfeed.

Keywords: Alzheimer’s risk factors; breastfeeding; cognitive health; dementia; lactation; reproductive life-history.

Figure 1.

Box-and-whiskers plot of cognitive domain z-scores by breastfeeding groups, showing the mean, median, quartiles, range, and outliers: X in the box represents the mean, the line represents the median and the box represents 50% of the data, distributed between the 1st and 3rd quartiles. The whiskers extend up to the largest data element that is less than or equal to 1.5 times the interquartile range (IQR) and down to the smallest data element that is larger than 1.5 times the IQR. Values outside this range are represented by dots. *P < 0.05 ** P < 0.01 *** P < 0.001.