A new study suggests that rates of mild memory problems may be higher than previously thought -- and men are at higher risk than women.
"We know that mild cognitive impairment [MCI] is important, but we've never had great estimates as to the frequency among men and women in different age groups," said Dr. Ralph Sacco, professor and chair of neurology at the University of Miami School of Medicine, who was not involved in the study.
"This quantitative information really helps to find the increasing burden of MCI," he continued. In general, people with mild cognitive impairment have issues beyond normal aging, but do not meet the criteria for dementia. They may have problems with memory, language and judgement that they or close friends and family recognize, but tend to function normally in society.
In the new study, published Wednesday in the journal Neurology, researchers from the Mayo Clinic looked at 1,450 adults from Olmsted County, Minn., age 70 to 89 who underwent memory testing every 15 months for an average of three years. At the study's start, none of the participants had cognitive impairment; when it concluded, nearly 300 adults had developed mild cognitive problems.
Overall, the researchers put the incidence of mild cognitive impairment at about 1 out of every 16 people and amnesic MCI -- in which memory problems predominate -- was more common than non-amnesic impairment, which tends to impact other cognitive functions, such as language and attention.
One interesting aspect of the study is that men were at higher risk for both types of impairment. Approximately one out of every 14 men had mild cognitive impairment, while only one out of every 18 women did.
In an accompanying editorial in Neurology, Dr. Kenneth Rockwood, director of geriatric medicine research at Dalhousie University in Nova Scotia, said that differences between the sexes are "no small thing" and noted they raise interesting questions because women tend to have a higher risk of dementia than men.
"It is unclear how to square more men in the at-risk state not translating into more men with dementia," Rockwood wrote, though he did suggest several hypotheses. One factor may be that men may simply die younger, meaning they do not have the chance to develop full-blown dementia.
Study author Rosebud Roberts of the Mayo Clinic and a member of the American Academy of Neurology, which publishes Neurology, told HuffPost that women may progress to full-blown dementia more quickly than men, or may bypass the mild cognitive impairment stage altogether.
"Men develop vascular diseases at earlier ages than women, which is an important risk factor [for mild cognitive impairment]" Roberts added. A growing body of evidence suggests that high blood pressure and other risk factors for stroke may lead to cognitive problems, damaging the arteries and resulting in potential loss of blood flow to the brain.
She said future research would attempt to clarify and investigate the differences in mild memory problems among men and women.
But not all cases of mild cognitive impairment lead to more dementia, and the new study found approximately 12 percent of people per year returned or reverted to normal. That estimate is on par with previous estimates and does not account for individuals who may then revert back to having mild cognitive impairment after further follow-up, the study's authors wrote, but it may provide some hope.
"There are things we can do with prevention. The things we do to improve heart health also impact brain health -- diet, exercise, not smoking," Sacco told HuffPost. "The real issue is that this is a dynamic process, and what we worry about is MCI getting worse."