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Women With MCI Decline Faster Than Men; Women at Higher Risk for Decline After Surgery/General Anesthesia

Women with mild cognitive impairment (MCI) have two times faster decline in cognition than men with MCI, according to new research reported at the Alzheimer's Association International Conference 2015 (AAIC 2015) in Washington, D.C. In addition, women decline more dramatically than men in cognition, function, and brain size after surgery and general anesthesia, according to another study reported at the conference.

MCI involves a slight but noticeable and measurable decline in cognitive abilities, including memory and thinking skills, but the changes are not severe enough to interfere with daily life or independent function. A person with MCI is at an increased risk of developing Alzheimer's or another dementia.
Women are at the epicenter of the Alzheimer's crisis. According to the Alzheimer's Association Alzheimer's Disease Facts and Figures report:

  • Almost two-thirds of American seniors living with Alzheimer's disease are women.
  • Among those aged 71 and older, 16% of women have Alzheimer's and other dementias, compared with 11% of men.
  • At age 65, women without Alzheimer's have more than a one in six chance of developing Alzheimer's during the remainder of their lives, compared with a one in 11 chance for men.
  • Women in their 60s are about twice as likely to develop Alzheimer's disease over the rest of their lives as they are to develop breast cancer.

"Women are disproportionately affected by Alzheimer's, and there is an urgent need to understand if differences in brain structure, disease progression, and biological characteristics contribute to higher prevalence and rates of cognitive decline," says Heather Snyder, PhD, Alzheimer's Association director of medical and scientific operations. "To intervene and help reduce the risk of Alzheimer's, it's critical to understand the reasons for these differences. Results presented at AAIC 2015 begin to shed light on this issue, but much more research is needed."

Toward this goal, the Alzheimer's Association is conducting a campaign—the Women's Alzheimer's Research Initiative—to raise $5 million; the Association plans to award a series of research grants specific to gender-related issues in Alzheimer's and other dementias. A recent Alzheimer's Association-convened think tank on "Gender Vulnerability Related to Alzheimer's Disease" looked deeply into these issues and plans to develop a manuscript of the meeting proceedings for publication. The focus was on three main topics that may link gender and vulnerability to Alzheimer's disease: biological mechanisms, hormonal factors and lifestyle factors.

Women at Risk for Alzheimer's and Dementia Decline Twice as Fast as At-Risk Men
Katherine Amy Lin, Wrenn Clinical Research Scholar in Alzheimer's disease, Duke University Medical Center, and colleagues used data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) to study how the cognitive abilities of about 400 people with MCI (141 women, 257 men), mostly in their mid-seventies, changed over the course of up to eight years.

They found a clear answer: cognitive abilities of women in the study with MCI declined twice as fast as men's—a result that was statistically significant.

Cognitive abilities were measured using the ADAS-Cog (Alzheimer's Disease Assessment Scale-cognitive subscale), one of the most frequently used tests to measure cognition in clinical trials, which has 11 parts and is scored from 0 to 70. The researchers found that the rate of decline in men was 1.05 points per year, in women it was 2.3 points per year. People of both genders with the ApoE4 Alzheimer's risk gene had a faster rate of decline. After adjusting for age, education, baseline Mini Mental State Examination score, follow up time and ApoE4 status, the effect of gender on ADAS-Cog rate of change was significant (p=0.005). The variability of cognitive change was also much greater in women than in men.

"Our findings suggest that men and women at risk for Alzheimer's may be having two very different experiences," Lin says. "Our analyses show that women with mild memory impairments deteriorate at much faster rates than men in both cognitive and functional abilities. These results point to the possibility of as yet undiscovered gender-specific genetic or environmental risk factors that influence the speed of decline. Uncovering those factors should be a high priority for future research."

"Because the ADAS-Cog is increasingly used as a cognitive outcome in prevention trials, our findings suggest the need to consider gender in the design and interpretation of such trials," Lin adds.

Women Decline Faster Than Men After Surgery/General Anesthesia
General anesthesia during surgery is a carefully monitored process because of its potential impact on the brain. Though the majority of people undergoing surgery have no lasting effects from the anesthesia, research has shown that older adults are at higher risk for long-term cognitive and functional problems following surgery with general anesthesia.

At AAIC 2015, Katie Schenning, MD, MPH, and colleagues from the Oregon Health & Science University, in Portland, Oregon, reported results from a study that explored whether exposure to general anesthesia would lead to faster deterioration of cognition, function, and brain volumes in women than in men. To study this question, the researchers reviewed two different research program databases that are examining cognitive aging—the Oregon Brain Aging Study and the Intelligent Systems for Assessing Aging Changes. Out of 527 total participants, 182 people underwent a total of 331 procedures under general anesthesia. The researchers found that:

  • Men exposed to general anesthesia during surgery declined in measures of cognition, functional status, and brain volumes statistically significantly faster than men who did not have surgery.
  • Women exposed to general anesthesia during surgery also declined on those measures, and at a significantly faster rate than men. That difference was even more pronounced for women who underwent multiple surgeries with general anesthesia.

"This is one of the first studies to suggest that among older adults, women are at a higher risk for postoperative brain dysfunction than men," Schenning says. "Our research clearly shows an association between surgery, general anesthesia, and cognitive decline in older adults. More studies are needed to confirm this observation and to identify ways to minimize the effects of surgery and general anesthesia on older adults. Future research should focus on whether certain people are more susceptible to postoperative cognitive decline by virtue of sex or genetic risk factors."

Source: Alzheimer's Association