Aging Issues: Stress May Affect Memory, Brain Size In Middle Age

Middle-aged people with high levels of the hormone cortisol in their blood have impaired memory when compared to those with average levels of the hormone - even before symptoms of memory loss start to show, according to a new study published in Neurology®, the medical journal of the American Academy of Neurology. People with high levels of the hormone also had lower brain volume than those with regular cortisol levels.

Cortisol - produced by the adrenal glands - helps the body respond to stress. It can also help reduce inflammation, control blood sugar and blood pressure, regulate metabolism, and help with immune response. High cortisol levels can be caused by stress, medical conditions or medications. “Cortisol affects many different functions so it is important to fully investigate how high levels of the hormone may affect the brain,” says study author Justin B. Echouffo-Tcheugui, MD, Ph.D., of Harvard Medical School in Boston, Mass. 

Researchers identified 2,231 people with an average age of 49 who were free of dementia. At the beginning of the study, each participant had a psychological exam and assessments for memory and thinking skills. Their memory and thinking skills were tested again an average of eight years later.  Participants also provided a blood sample taken in the morning after a period of fasting. Researchers measured cortisol levels in the blood and then divided participants into low, middle and high groups, with those in the middle group having cortisol levels in the normal range, between 10.8 and 15.8 micrograms per deciliter. A total of 2,018 participants also had an MRI brain scan to measure brain volume. 

After adjusting for age, sex, smoking, and body mass index, researchers found that people with high levels of cortisol had lower scores on tests of memory and thinking skills than those with normal levels of cortisol. High cortisol was also linked to lower total brain volume. Those with high cortisol had an average total cerebral brain volume of 88.5 percent of total cranial volume compared to 88.7 percent of total cranial volume in those with normal levels of cortisol. No links were found between low cortisol levels and memory or brain size. “Our research detected memory loss and brain shrinkage in middle-aged people before symptoms started to show, so it’s important for people to find ways to reduce stress, such as getting enough sleep, engaging in moderate exercise, incorporating relaxation techniques into their daily lives, or asking their doctor about their cortisol levels and taking a cortisol-reducing medication if needed,” said Echouffo-Tcheugui. “It’s important for physicians to counsel all people with higher cortisol levels.” 

Cortisol levels in the blood were measured only once and may not represent long-term exposure to the hormone. Participants were mostly middle-aged with European ancestry so results do not reflect the population as a whole.

Does Facial Asymmetry Increase With Age? 

Asymmetry between the two sides of the face increases steadily with aging. This is a finding with important implications for facial rejuvenation and reconstructive procedures, reports a study in the November 2018 issue of Plastic and Reconstructive Surgery. Three-dimensional digital imaging techniques show a subtle but significant aging-related increase in facial asymmetry, especially in the lower two-thirds of the face, according to new research by ASPS Member Surgeon Helena O.B. Taylor, MD, Ph.D., of Mount Auburn Hospital, Cambridge, Mass., and colleagues. "The observed correlation between increasing facial asymmetry and age can be useful as a guide in plastic surgery to produce age-matched features," the researchers added.

The researchers used a technique called 3D photogrammetry to perform detailed scans of the facial surface in 191 volunteers ranging in age from four months to 88 years. The researchers then calculated the "root mean square deviation" (RMSD) to quantify the degree of asymmetry between the two sides of each face. This digital imaging approach enabled the investigators to distinguish very subtle levels of asymmetry within a fraction of a millimeter. Facial asymmetry was analyzed in terms of age, and between the upper, middle, and lower thirds of the face. Across age groups, RMSD calculations of facial symmetry clustered between 0.4 and 1.3 mm. "We found a highly significant positive correlation between increasing age and facial asymmetry," the researchers stated. The measurements showed a small but predictable increase in RMSD: by 0.06 millimeters for each decade of life. Facial asymmetry did not vary significantly based on race or sex.

Asymmetry increased with aging across all thirds of the face, but the changes were greatest in the lower two-thirds from the eyebrows to nose and from the nose to chin compared to the upper third. "This finding suggests that the middle and lower features contribute more to overall asymmetry over time," says Dr. Taylor. While some degree of asymmetry is "attractive and inherent" in the human face, achieving facial symmetry is a fundamental goal of plastic surgery. In terms of precision and accuracy, 3D photogrammetry is a major advance over previous studies of facial asymmetry using direct measurements or anthropometry.

The results confirm the presence of small but measurable and noticeable increases in facial asymmetry with aging. While the underlying mechanism of these age-related changes remains open to debate, the findings support "a site-specific approach to facial rejuvenation," Taylor added. "Ultimately, we hope to contribute to a better understanding of how asymmetry evolves with time and use this data to improve outcomes in both reconstructive and aesthetic surgery." For example, using implants or soft tissue volumizers to replace the deep support structures could improve facial asymmetry and restore youthful proportions, especially from the eyebrows down to the chin.

Are Awareness Of Aging And Mood Affected By Daily Experiences?

A study of older adults finds an individual's awareness of aging is not as static as previously thought, and that day-to-day experiences and one's attitude toward aging can affect an individual's awareness of age-related change (AARC) and how that awareness affects one's mood. "People tend to have an overall attitude toward aging, good or bad, but we wanted to know whether their awareness of their own aging or AARC fluctuated over time in response to their everyday experiences," says Shevaun Neupert, an associate professor of psychology at North Carolina State University and lead author of a paper on the study.

Researchers enrolled 116 participants between the ages of 60 and 90. Each participant took a survey to establish baseline attitudes toward aging. For the following eight days, participants kept a log of daily stressors such as having an argument, completed a daily evaluation of age-related experiences such as "I am becoming wiser" or "I am more slow in my thinking", and reported on their affect or mood. "We found that people's AARC, as reflected in their daily evaluations, varied significantly from day to day," says Jennifer Bellingtier, a recent Ph.D. graduate from NC State and co-author of the paper. "We also found that people whose baseline attitudes toward aging were positive also tended to report more positive affect or better moods." "People with positive attitudes toward aging were also less likely to report 'losses,' or negative experiences, in their daily aging evaluations," Neupert says. "However, when people with positive attitudes did report losses, it had a much more significant impact on their affect that day," Neupert says. "In other words, negative aging experiences had a bigger adverse impact on mood for people who normally had a positive attitude about aging."

The study expands on previous work that found having a positive attitude about aging makes older adults more resilient when faced with stressful situations.

Centenarians And Chronic Illness

Centenarians have a lower incidence of chronic illness than those in their 80s and 90s, according to research from the George Washington University. The centenarian population is one of the fastest growing in the country, according to the United States Social Security Administration. They are predicted to exceed one million by the close of this century, but little is known about why this generation has achieved such longevity. Raya Elfadel Kheirbek, MD, MPH, associate professor of medicine at the GW School of Medicine and Health Sciences, and geriatrician and palliative care physician at the Washington, D.C. Veteran Affairs Medical Center (VA), wanted to understand what factors contributed to their long life.

Kheirbek and her team looked primarily at octogenarians, nonagenarians, and centenarians within the VA. The sample that they studied comprised mostly of white males that had fought in World War II. The results were published in the Journal of the American Geriatric Society. "Additionally, this generation lived through the Great Depression," said Kheirbek. "It is a wonder, considering the hardships they had faced, that they have achieved such longevity. This never before studied group of centenarians at the VA imparts a very important message of resilience to anyone struggling as they did."

A key factor that Kheirbek and her team observed in these individuals is that, due to their military background, many had a developed sense of discipline and therefore were keen to make healthy decisions; many did not smoke or drink. The team also offered the hypothesis of compression morbidity as a potential explanation for the extended health span in an individual's life span. The hypothesis states that the lifetime burden of illness could be reduced if the onset of chronic illness is postponed until very late in life, or as Kheirbek put it, "the older you get, the healthier you have been." Her work with a 108-year-old woman inspired the study.

Learn more about the brain at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life on FacebookTwitter and Instagram.


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