Are There Cognitive Side Effects of Perimenopause?

I’ve heard that one of the symptoms of menopause is having moments when you can’t access the word you want — spacing on vocabulary. I have definitely experienced this. Is this true? Why does it happen? Does it go away after menopause? When is it an indicator of early-onset Alzheimer’s?
—45 and curious

It is true that about two-thirds of women report cognitive symptoms during the perimenopausal years. Women typically report difficulty with word finding as you describe, losing their train of thought, and more generalized brain fog or a feeling that thinking is slow and lacking clarity.

A woman’s subjective report of cognitive symptoms does seem to be correlated with performance on objective tests of cognitive function. In a study of 130 perimenopausal women, those who reported subjective cognitive symptoms did have lower scores on tests of attention, though their scores were still normal. In another study of 75 perimenopausal women, the degree of perceived memory difficulty was associated with worse performance on tests of working memory and complex attention.

There are likely a number of reasons these symptoms occur. During perimenopause, women report poor sleep. While we don’t fully understand the purpose of sleep, we know that not getting enough sleep objectively decreases cognitive performance.

However, that is likely not the whole story. Estrogen has been found to have direct effects on the brain. It enhances the effects of chemicals in the brain that allow nerve cells to communicate with one another. Estrogen may improve the function of mitochondria, the energy-generating centers in cells. Brain cells require tons of energy to function well, and mitochondrial function is critical to providing that energy. Estrogen may also act as an antioxidant, protecting our brain cells from damaging free radicals.

The declines seen in cognitive function do seem to persist after menopause. In one study of 200 people, men and women, perimenopausal women outperformed men on tests of cognitive function. After menopause, the differences in performance between men and women disappeared.

Many studies have looked at whether giving women estrogen as hormone replacement therapy (HRT) improves cognitive performance. For example, the KEEPS study randomized nearly 700 perimenopausal women to receive one of two HRT combinations or a placebo. The participants took tests of cognitive function at various time points before and after starting HRT or placebo. After four years of HRT, there was no difference in test scores between the HRT groups and the placebo group.

However, there is no evidence to suggest that the cognitive symptoms women experience in midlife are connected with the development of dementia in later life. The loss of estrogen during menopause does seem to play a role in developing dementia, but the biochemical mechanism seems to be different from the biochemical changes associated with cognitive symptoms in midlife.

The takeaway: Yes, many women experience cognitive changes during perimenopause, but those changes are not associated with early dementia.