Men have the notorious reputation of forgetting birthdays, anniversaries, and other important dates. On the other hand, women are better at recalling memories faster, more accurately, and in specific detail. A new study published in the journal Menopause suggests there's a science behind these gender differences in memory.

Researchers from The North American Menopause Society (NAMS) found middle-aged women outperform age-matched men when it comes to measures of memory. However, memory does decline as women enter postmenopause. Previous research suggest these declines are associated with low estrogen levels after menopause.

"Findings underscore the significance of the decline in ovarian estradiol production in midlife and its role in shaping memory," wrote the researchers.

Brain fog and short-term memory loss is common in women during menopause and postmenopause. Low estrogen levels have a direct impact on brain neurotransmitters dopamine, serotonin, and GABA. They help regulate mood, cognitive function such as thinking and memory, and enable us to manage stress. However, when estrogen levels are low, these neurotransmitters become out of balance, which could result in mood disorders, an inability to think clearly, and short-term memory issues.

Despite conditions working against them, middle-aged women can still outscore their similarly aged male counterparts on all memory measures.

The researchers from NAMS recruited a total of 212 men and women aged 45 to 55 to undergo clinical and cognitive testing and hormonal assessments of menopause status. Memory measures, including episodic memory (recalling autobiographical events), executive function (cognitive processes like working memory), semantic processing (processes that occur after hearing a word, and encoding its meaning), and estimated verbal intelligence (ability to analyze information and solve problems using language-based reasoning) were assessed. Associative memory and episodic verbal memory were measured using Face-Name Associative Memory Exam (FNAME) and Selective Reminding Test (SRT), which can detect early cognitive decline. The influence of sex and reproductive stage on performance was also tested.

In addition to comparing sex differences, the researchers found premenopausal (before menopause when women still have regular menstrual cycles) and perimenopausal (menopause transition when women make less estrogen) women outperformed postmenopausal women in a number of key memory areas. In postmenopausal women, low estradiol levels, a female sex hormone produced in the ovaries, were specifically associated with lower rates of initial learning and remembering previously recalled information, while memory storage and consolidation were not affected. Estradiol has a significant impact on reproductive and sexual function as well as on other organs, including the bones.

"Brain fog and complaints of memory issues should be taken seriously," said Dr. JoAnn Pinkerton, NAMS executive director, in a statement. "This study and others have shown that these complaints are associated with memory deficits."

A similar 2015 study found women do outperform men in memory-related tasks because they tend to possess higher brain volumes than men. The hippocampus, the part of the brain that controls memory, also is smaller than that of women's, especially after age 60. It falls way below average in the older men as compared to older women. Researchers attribute this to the protective effects of female hormones. Estrogen has been shown to protect premenopausal women from hypertension, bone loss, heart disease, and even urinary tract infections.

Women’s hormones provide neuroprotective effects that go well into middle age, compared to men. Researchers hope to explore what specific memory changes are experienced by women in early midlife that are linked to healthy aging, and what memory deficits could be indicators of memory decline, like dementia and Alzheimer’s disease later in life.

Source: Rentz DM, Weiss BK, Jacobs EG et al. Sex differences in episodic memory in early midlife: impact of reproductive aging. Menopause. 2016.