Alcohol’s negative effect on women’s working memory is somewhat mitigated when their estrogen levels are higher, a novel study suggests. The findings imply that phases of the menstrual cycle may influence women’s vulnerability to the acute effects of alcohol on certain cognitive functions. Working memory is vital for understanding, reasoning, and learning. Studies have shown that drinking impairs working memory, with higher blood alcohol concentrations (BAC) linked to worse performance. Women may experience less alcohol-related working memory impairment than men, though this is unclear, and the potential relevance of hormonal factors is largely unknown. Some research suggests that heightened estradiol—the most prominent form of estrogen among women of reproductive age—might benefit working memory most in situations when that cognitive function is compromised, such as after menopause or drug use. For the study in Alcohol: Clinical & Experimental Research, investigators at the University of Kentucky explored alcohol’s impact on working memory across phases of the menstrual cycle characterised in part by varying levels of estradiol.

The researchers worked with 75 women aged 21–34 who drank alcohol at least once a week (but did not have alcohol use disorder) and who did not use hormonal birth control. The participants reported their alcohol consumption over the previous month. In the lab, they underwent two testing sessions scheduled according to their menstrual cycles. During each session, they consumed a drink (alcoholic or placebo), completed some cognitive tests, consumed the other drink, and repeated the tests. The first testing session occurred within their early follicular phase, days 4–7 of their cycles (commonly the tail end of a menstrual period). The second testing session took place within the late follicular phase, days 11–14, when estradiol levels rise in preparation for ovulation. The women underwent computerised tests of working memory and a pegboard test assessing motor coordination. Their hormone levels were assessed via saliva samples, and their BAC was assessed via a breathalyser. They reported how intoxicated, stimulated, or sedated they felt after drinking. The researchers used statistical analysis to identify associations between alcohol use, cycle phase, and cognitive performance.

The participants reported an average of 25 alcoholic drinks consumed over about 9 days during the previous month. Their estradiol levels were higher during the late follicular phases of their menstrual cycles than the early follicular phases. During testing, their BAC levels were similar across different cycle phases, and their working memory performance was worse after consuming alcohol than placebo. During the late follicular phases of their cycles, however, when their estradiol levels were higher, the women’s working memory scores were somewhat less affected by alcohol than during their early follicular phases. While sober, their working memory performance did not vary by cycle phase. Their motor skills were worse after consuming alcohol, but the scale of that impairment did not differ by cycle phase. Their perceptions of their alcohol intoxication, stimulation, and sedation were similarly not affected by cycle phase.

The findings add to evidence that the late follicular cycle phase of the menstrual cycle may protect against certain cognitive vulnerabilities to alcohol and that the benefits of heightened estradiol on working memory may be especially evident when that cognitive process is impaired. It’s possible that women’s ability to regulate their drinking—a process involving working memory—varies according to cycle phase. Further research is needed involving women using hormonal birth control or hormone therapy and postmenopausal women.