A study conducted by American scientists showed that women with Alzheimer’s disease retain verbal (verbal) memory longer than men – even with a comparable decrease in the volume of the brain area responsible for these functions.
“Perhaps, the fact is that in women at any age, on average, verbal memory is better developed than in men, therefore, with the development of Alzheimer’s disease, they have a certain “margin of safety”, due to which these functions last longer.
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Since Alzheimer’s disease and the mild cognitive impairment that precedes it are diagnosed using tests that specifically test verbal memory, there is a risk that we may miss the initial stages of the development of the disease in women, ”says Erin Sundermann, lead author of the study, who works at the College of Medicine named after Albert Einstein (New York, USA).
The study analyzed data from 236 patients with Alzheimer’s disease or other types of dementia, 694 patients with mild cognitive impairment (they often precede the development of dementia) and 379 healthy volunteers.
They were all part of another major disease study that included verbal memory testing and brain scans to assess the degree of atrophy (shrinkage) in a region of the brain called the hippocampus as a result of the disease. The hippocampus is responsible, in particular, for the functioning of verbal memory.
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The analysis showed that among patients who had a slight or moderate degree of hippocampal atrophy, women showed better results in verbal memory tests than men. However, in patients with severe hippocampal atrophy, there was no significant gender difference in test scores.
At the same time, when comparing the condition of patients in whom the test results showed the initial stages of verbal memory deterioration (37 or less points on a scale from 0 to 75), it turned out that in women at this stage, hippocampal atrophy is more pronounced (since a more moderate degree of atrophy in them, unlike men, has not yet affected the test results).
Notably, in healthy volunteers, no relationship was found between hippocampal volume and performance on verbal memory tests. Similar results have been observed in previous similar studies. Scientists suggest that a decrease in the volume of the hippocampus begins to affect memory only when a certain “threshold” is passed.
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Perhaps these results help explain the statistical paradox that men are more likely to be diagnosed with mild cognitive impairment, while women are more likely to be diagnosed with Alzheimer’s disease. “Perhaps because of women’s initial superiority in verbal memory functioning, they are usually later diagnosed with mild cognitive impairment, but when function decline does begin, it can go even faster,” says Erin Sandermann.
Scientists believe that existing standards for testing and diagnostics need to be reworked to take into account differences between the sexes so that cognitive impairment in women can be detected at an early stage.
Подробнее см. Е. Sundermann et al. «Better verbal memory in women than men in MCI despite similar levels of hippocampal atrophy», Neurology, March 2016.