Because women generally have better verbal memory than men, researchers speculate that this may protect the verbal memory of women in the early stages of Alzheimer's.
Around 5.3 million people in the US have Alzheimer's disease, of whom around 3.1 million are women.
Problems with memory is one of the earliest signs of the neurological disorder, with memory impairments worsening as the disease progresses.
Research has suggested that, in general, women have better verbal memory than men. That is, they have a better ability to recall words and other factors related to language.
For this latest study, Dr. Erin E. Sundermann, of the Albert Einstein College of Medicine in Bronx, NY, and colleagues set out to determine whether this difference persists in the early stages of Alzheimer's disease.
The team notes that identifying sex differences in verbal memory deficits is clinically important because such deficits are considered when making a diagnosis of amnestic mild cognitive impairment (aMCI) or Alzheimer's.
"A true aMCI diagnosis may be delayed more often in women than men because the female advantage in verbal memory may mask underlying neurodegeneration, particularly in earlier disease stages," they add.
A 'buffer of protection' for women in early Alzheimer's
The study included 235 participants with Alzheimer's or other dementias, 694 participants with aMCI and 379 participants with no memory or thinking problems.
All subjects were a part of the Alzheimer's Disease Neuroimaging Initiative (ADNI), in which they completed the Rey Auditory Verbal Learning Test (RAVLT) - used to assess immediate and delayed verbal memory - and underwent brain imaging.
- In the US, someone develops Alzheimer's every 67 seconds
- It is the sixth leading cause of death in the country
- It is estimated that around 13.8 million people in the US aged 65 and older will have Alzheimer's by 2050, unless new treatments are found.
The researchers compared the participants' results on the memory test with the size of their hippocampus - the brain region that controls verbal memory and is implicated in the early stages of Alzheimer's.
Among individuals with minimal to moderate levels of hippocampal shrinkage, women did better than men on the verbal memory tests, while no difference in verbal memory performance was identified between men and women with high levels of hippocampal shrinkage.
Additionally, the team found that among subjects with aMCI who had minimal to moderate hippocampal shrinkage, women performed better on verbal memory tests than men, but this link was not found among participants with aMCI who had higher hippocampal shrinkage.
However, among participants with verbal memory test scores that represent the beginning of verbal memory impairment, women demonstrated greater levels of hippocampal shrinkage than men.
All in all, the researchers believe their findings suggest that women have an advantage over men when it comes to verbal memory in the early stages of Alzheimer's disease, despite still experiencing minimal to moderate hippocampal shrinkage.
"One way to interpret the results is that because women have better verbal memory skills than men throughout life, women have a buffer of protection against loss of verbal memory before the effects of Alzheimer's disease kick in," says Dr. Sundermann.
The authors say their results could have important clinical implications for Alzheimer's diagnosis:
"If replicated, our findings suggest the need to evaluate whether diagnosis of aMCI is made at a later disease stage in women compared to men because this sex-specific advantage in verbal memory masks underlying neurodegeneration. If so, then sex-based norms in clinical memory tests might improve diagnostic accuracy in women."
Medical News Today recently reported on a study that suggests blueberries could be used to fight Alzheimer's.