A study involving 2,050 people aged 70 to 89 has found that mild cognitive impairment was 1.5 times more common in men than women. Among the 1,969 who did not have dementia, over 16% (329) had MCI — around 11% amnestic MCI (MCI-A) and 5% non-amnestic (MCI-MCD). A total of 19% of men had MCI, compared to 14% of women. MCI was also more common among the never-married, those with the APOEe4 (Alzheimer’s risk) gene, and those with less education.
This is the first study conducted among community-dwelling persons to find a higher prevalence of MCI in men. However, I note that some years ago I reported on a Dutch study involving some 600 85-year-olds, that found that significantly more women than men had a good memory (41% vs 29%; good mental speed on word and number recognition tests was also found in more women than men: 33% vs 28%). This was considered particularly surprising, given that significantly more of the women had limited formal education compared to the men.
The researchers suggested biological factors such as the relative absence of cardiovascular disease in the women might account for the difference. I would suggest another factor might be social, given that social stimulation has been shown to help prevent cognitive decline, and women are more likely than men to keep up social links in old age.
 . Prevalence of mild cognitive impairment is higher in men: The Mayo Clinic Study of Aging. Neurology [Internet]. 2010 ;75(10):889 - 897. Available from: http://www.neurology.org/cgi/content/abstract/75/10/889