Researchers found that women with mild cognitive impairment (MCI) are twice more at risk to develop cognitive decline compared to men. The report, presented at the Alzheimer's Association International Conference® 2015 (AAIC® 2015) in Washington, D.C., was complemented by another study which found that women deteriorate faster than men in terms of brain function and size after a surgical procedure and administration of general anesthesia.

For the first study, the researchers led by Katherine Amy Lin, Wrenn Clinical Research Scholar in Alzheimer's disease, Duke University Medical Center investigated the data found in the Alzheimer's Disease Neuroimaging Initiative (ADNI), which involved approximately 400 individuals diagnosed with MCI. The participants were composed of 257 men and 141 women, who are mostly in their mid-seventies. The researchers aim to identify the manner in which cognitive functions change over the course of 80 years by analyzing the neuroimaging data of these participants. The method of testing used is the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog), which measures an individual's cognition based on 11 categories and yields a score ranging from 0-70.

The findings of this study found that the annual cognitive decline rate in men and women is 1.05 points and 2.3 points respectively. The researchers were also able to identify the participants who possess the ApoE4 Alzheimer's risk gene and found them to have more rapid decline rates. Other factors such as education, age, initial Mini Mental State Examination score, follow up time and presence of ApoE4 were adjusted but the impact of gender on the ADAS-Cog results were still notable. In the end, the researchers conclude that their study found that women with MCI are twice more likely to decline than men as per statistical analysis.

"Our findings suggest that men and women at risk for Alzheimer's may be having two very different experiences," said Lin. The results of the study may suggest that unknown factors, which may be environmental, genetic or gender-specific may influence the rate of decline, she adds. Future researches should emphasize on these factors.

The second study presented in the convention, led by Katie Schenning, MD, MPH from the Oregon Health & Science University, investigated whether administration of general anesthesia may result in more rapid cognitive, functional and brain size decline in women than in men. The researchers conducted their study by studying the databases of two research programs namely the Oregon Brain Aging Study and the Intelligent Systems for Assessing Aging Changes. Both of these systems focus on cognitive aging and involve a total of 527 study subjects of whom 182 have already underwent 331 operations involving general anesthesia.

The findings of the study show that men who were exposed to general anesthesia exhibited a statistically significant decline in brain volume, cognitive status and functionality, compared to those who did not have an operation. The researchers also found that women who were administered with general anesthesia showed much higher decline rates in all the three aspects compared to men. A more significant deviation was noted in women who underwent multiple operations under 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," said Schenning. According to him, more research is warranted to confirm their findings and determine measures that can help to keep anesthesthetic effects of older adults to a minimum.

MCI is a mild form of cognitive decline, which is characterized by minimal yet noticeable and measurable decrease of memory and thinking skills. People diagnosed with MCI are said to have an increased risk of developing Alzheimer's disease or other forms of dementia.

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