Men more than women are at higher risk of developing mild memory loss, according to a new study published in the journal Neurology. The memory dysfunction, called mild cognitive impairment, or MCI, is the stage between normal brain aging and dementia.
The study has stirred interest, as many other studies have found that women are at higher risk of developing dementia than are men.
"Since MCI is a risk factor for dementia, and large numbers of the baby boomer generation are reaching this age, we must prevent or reduce the risk of MCI, or the increased development of dementia will have a tremendous impact on the cost of health care in elderly persons," said Dr. Rosebud Roberts, lead author of the study and a neurologist at the Mayo Clinic in Rochester, Minn.
MCI is common in older adults, and often adults realize that their memory or mental function has declined. While research has found that people with MCI are at higher risk of developing Alzheimer's disease, MCI will not always develop into the more severe condition of dementia or Alzheimer's.
In the study, researchers analyzed 1.450 adults between the ages of 70 and 89 who were free of dementia when they joined the trial. Over a three-year period, study participants went through a battery of memory tests every 15 months. By the end of the trial, 296 participants had developed MCI.
Researchers found that 7.2 percent of men developed MCI, compared with 5.7 percent of women. People who were not married and those who had less education were also more likely to experience MCI.
While the reasons for the findings are not clear, Roberts said risk factors for MCI may occur earlier and at a higher rate in men than in women.
"Women may develop risk factors for MCI at a later age, but the effects may be more severe when they occur," said Roberts. "Women may ... progress faster to dementia, or they may progress to dementia without being diagnosed at the MCI stage."
"We've always suspected that there are many people who do not have a diagnosis in the community who are living at this level of cognitive impairment," said Bill Thies, chief medical and scientific officer at the Alzheimer's Association. "The study suggests that we should have increasing concern about people living in the community with cognitive problems. We're only seeing the tip of the iceberg."
MCI is a syndrome, not a particular disease, Dr. Claudia Kawas, a professor in the department of neurology and neurobiology and behavior, said in an email.
"It is often due to early Alzheimer's disease but can also be due to strokes, vitamin deficiencies, thyroid disease, drugs including prescription ones, alcohol or just not feeling well that day," said Kawas. "It will be interesting to see if men with MCI develop Alzheimer's disease at the same or different rate as women."
In the future, "increased efforts should be made to understand differences in risk factors for MCI in men and women [and] efforts to prevent or control these risk factors should be sex specific," said Roberts.
Thies said the medical community is not prepared to deal with the influx of Alzheimer's disease that is expected to occur in the next 40 years. While cancer, heart disease and AIDS each receive about $5 billion to 6 billion in research investments per year, Alzheimer's receives a few hundred million, Thies said. He predicted the cognitive condition would not see breakthrough treatments in the same way the other major diseases had without adequate investment in new research and treatment.
"The medical care system is not organized to deal with cognitive dysfunction in the community, and it's only going to get worse," said Thies. "The post-World War II baby boomers will see a large influx of Alzheimer's and dementia, and until we start to invest at a significant level, we're not going to see the necessary changes and better therapies that are needed to combat this disease."