'Stressors' in middle age linked to cognitive decline in older women
August 5, 2019
Science Daily/Johns Hopkins Medicine
A new analysis of data on more than 900 Baltimore adults by Johns Hopkins Medicine researchers has linked stressful life experiences among middle-aged women -- but not men -- to greater memory decline in later life.
The researchers say their findings add to evidence that stress hormones play an uneven gender role in brain health, and align with well-documented higher rates of Alzheimer's disease in women than men.
Although the researchers caution their study was designed to show associations among phenomena, and not determine cause and effect, they say that if future studies demonstrate that stress response does factor into the cause of dementia, then strategies designed to combat or moderate the body's chemical reactions to stress may prevent or delay onset of cognitive decline.
The findings are published in the July issue of the International Journal of Geriatric Psychiatry.
According to the Alzheimer's Association, 1 in 6 women over age 60 will get Alzheimer's disease, compared with 1 in 11 men. There currently are no proven treatments that prevent or halt progression of the disease.
"We can't get rid of stressors, but we might adjust the way we respond to stress, and have a real effect on brain function as we age," says Cynthia Munro, Ph.D., associate professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine. "And although our study did not show the same association for men, it sheds further light on the effects of stress response on the brain with potential application to both men and women," she adds.
Munro says prior research by other investigators shows that the effect of age on the stress response is three times greater in women than in men. Separately, other research has shown that stressful life experiences can result in temporary memory and cognitive problems.
To further explore whether stressful life experiences can be linked to developing long-term memory problems in women especially, Munro and her team used data collected on 909 Baltimore residents for the National Institute of Mental Health Epidemiologic Catchment Area study. That study recruited participants from 1981 to 1983 from five cities in the U.S. to determine the prevalence of psychiatric disorders.
Some 63% of the participants were women and 60% were white. Participants were an average age of 47 during their mid-life check-in in the 90s.
After enrollment, participants returned to trial sites for interviews and checkups three additional times: once in 1982, once between 1993 and 1996, and once between 2003 and 2004.
During the third visit, participants were asked if they experienced a traumatic event in the past year such as combat, rape, a mugging, some other physical attack, watching someone else attacked or killed, receiving a threat, or living through a natural disaster. Some 22% of men and 23% of women reported at least one traumatic event within the past year before their visit.
They also were asked about stressful life experiences such as a marriage, divorce, death of a loved one, job loss, severe injury or sickness, a child moving out, retirement, or birth of a child. About 47% of men and 50% of women reported having at least one stressful life experience in the year before their visit.
At the third and fourth visits, the researchers tested the participants using a standardized learning and memory test developed by Iowa researchers. The test included having participants recall 20 words spoken aloud by the testers immediately after they heard them, and again 20 minutes later.
At the third visit, participants could recall on average eight words immediately and six words later. Participants also had to identify the words spoken to them among a written list of 40 words. During the third visit, participants correctly identified on average 15 words. By the fourth visit, participants recalled an average of seven words immediately, six words after a delay, and correctly recognized almost 14 words.
The researchers measured any decreases in performance on the tests between the third and fourth visits, and then compared those decreases with participants' reports of stressful life experiences or traumatic events to see if there was an association.
Munro's team found that having a greater number of stressful life experiences over the last year in midlife in women was linked to a greater decline in recalling words later and recognizing those words. Women who experienced no stressful life experiences within the past year at the third visit were able to remember on average 0.5 fewer words when given the same memory test at the fourth visit. Women with one or more stressful life experiences, however, recalled on average one fewer word at the fourth visit than they had at the third visit. The ability to recognize words declined by an average of 1.7 words for women with at least one stressor at the third visit compared with a 1.2-word decline for women without stressors at midlife.
They didn't see the same trend in women who had traumatic events. Munro says that this finding suggests that ongoing stress, such as that experienced during a divorce, may have more of a negative impact on brain functioning than distinct traumatic events. This makes sense, Munro believes, because what we call "chronic stress" can impair the body's ability to respond to stress in a healthy manner.
The researchers did not see an association in men between a drop in word recall or recognition and experiencing either stressful life experiences or traumatic events in midlife.
Stress much earlier in life also wasn't predictive of cognitive decline later in either men or women.
"A normal stress response causes a temporary increase in stress hormones like cortisol, and when it's over, levels return to baseline and you recover. But with repeated stress, or with enhanced sensitivity to stress, your body mounts an increased and sustained hormone response that takes longer to recover," says Munro. "We know if stress hormone levels increase and remain high, this isn't good for the brain's hippocampus -- the seat of memory."
The researchers say that stress reduction hasn't gotten a whole lot of attention compared with other factors that may contribute to dementia or Alzheimer's, and that it might be worth exploring stress management techniques as a way to delay or prevent disease.
Munro adds that there are medications being developed to combat how our brains handle stress, and that these may be used in conjunction with other behavioral stress coping techniques to reduce the impact of stress on aging minds.
https://www.sciencedaily.com/releases/2019/08/190805101144.htm
Changes in stress after meditation
June 21, 2018
Science Daily/U.S. Army Research Laboratory
For a thousand years, people have reported feeling better by meditating but there are few systematic studies that quantified stress and how much stress changes as a direct result of meditation, until now.
U.S. Army Research Laboratory researchers spent a year collaborating with a team of scientists from the University of North Texas to develop a new data processing technique that uses heart rate variability as a sensor to monitor the state of the brain. Their findings are reported in a paper published in the June edition of Frontiers in Physiology.
Healthy heartbeats have irregularities built into them with a slight random variation occurring in the time interval between successive beats. The sinus node, or the heart's natural pacemaker, receives signals from the autonomic or involuntary portion of the nervous system, which has two major branches: the parasympathetic, whose stimulation decreases the firing rate of the sinus node, and the sympathetic, whose stimulation increases the firing rate. These two branches produce a continual tug-of-war that generates fluctuations in the heart rate of healthy individuals.
Heart rate variability provides a window through which we can observe the heart's ability to respond to external disturbances, such as stress, said Dr. Bruce West, the Army's senior research scientist for mathematics.
He said it turns out that the HRV time series is very sensitive to changes in the physiological state of the brain and the new data processing system, called dynamic subordination technique, can quantify the changes in HRV and relate these directly to brain activity, such as produced by meditation. Thus, the DST has quantified the level of stress reduction produced by meditation and offers the potential to quantify such things as the inability to concentrate and sustain focus, impatience, impulsiveness and other dysfunctional properties that severely limit a soldier's ability to do his job.
Stress modulates the autonomic nervous system signals, which in turn disrupts normal HRV and therefore the stress level can be detected by processing HRV time series.
Through a new method of processing HRV time series data, the researchers developed a way to measure the change in the level of stress provided by meditation. This measure assigns a number to the level of variability of heartbeat interval time series before and during meditation. This number indicates precisely how much stress is alleviated by control of the heart-brain coupling through meditation.
In the article, Rohisha Tuladhar, Gyanendra Bohara, and Paolo Grigolini, all from the University of North Texas and Bruce J. West, Army Research Office, propose and successfully test a new model for the coupling between the heart and brain, along with a measure of the influence of meditation on this network. Traditional models of biofeedback focus on the coherent behavior, assuming a kind of resonance, however the new approach includes both periodicity and complexity.
The research team compared two schools of meditation and determined that Yoga, over Chi meditation, is more effective in reducing stress and can show by how much. They also found that the long-term practice of meditation has the effect of making permanent the meditation-induced physiologic changes. Moreover that meditators show a stronger executive control, that is, the ability to carry out goal-oriented behavior, using complex mental processes and cognitive abilities.
Many military historians believe battles, even wars, have been won or lost in the warrior's mind, long before any physical conflict is initiated. Learning how to circumvent the debilitating psychological influence of stress requires that we have in hand a way to quantify its influence, in order to gauge the effectiveness of any given procedure to counteract its effects, explained West, who's a Fellow with the American Physical Society, American Association for the Advancement of Science and ARL.
Historically, one purpose of meditation has been to reduce stress, however, the Army's long-term goal is to use it to mitigate the effects of post-traumatic stress disorder, or PTSD. West said the potential for this to succeed has been dramatically increased with the new ability to quantify the degree of effectiveness in stress reduction using different meditation techniques.
From a physiological perspective, meditation constitutes a coupling of the functionalities of the heart and brain. We are only now beginning to understand how to take advantage of the coupling of the two to measure stress reduction by applying the methods of science and data analysis to HRV time series.
Our research focus is on changes in physiologic processes, such as stress level. It is the most direct measure of the effectiveness of meditation in reducing stress to date and compliments an existing ARL program on determining the efficacy of mindfulness meditation stress reduction, which quantifies the influence on different task performance measures, such as changes in PTSD symptoms, West said.
This early research could guide the design and testing of new interventions for improving warrior readiness and resilience, as well as reducing symptoms of PTSD.
https://www.sciencedaily.com/releases/2018/06/180621111955.htm
Stress reduction and mindful eating curb weight gain among overweight women
December 7, 2011
Science Daily/University of California - San Francisco
Mastering simple mindful eating and stress-reduction techniques helped prevent weight gain even without dieting in overweight women.
In a study by UCSF researchers published online in the Journal of Obesity, mastering simple mindful eating and stress-reduction techniques helped prevent weight gain even without dieting.
Women in the study who experienced the greatest reduction in stress tended to have the most loss of deep belly fat. To a greater degree than fat that lies just under the skin, this deep abdominal fat is associated with an elevated risk for developing heart disease or diabetes.
"You're training the mind to notice, but to not automatically react based on habitual patterns -- to not reach for a candy bar in response to feeling anger, for example," said UCSF researcher Jennifer Daubenmier, PhD, from the Osher Center for Integrative Medicine. "If you can first recognize what you are feeling before you act, you have a greater chance of making a wiser decision."
Daubenmier led the current study with UCSF psychologist Elissa Epel, PhD. The study, published online in October, is part of ongoing UCSF research into how stress and the stress hormone cortisol are linked to eating behavior, fat and health.
Recognizing Sensations of Hunger, Fullness and Taste Satisfaction
The women who participated were not on calorie-counting diets. Instead, 24 of the 47 chronically stressed, overweight and obese women were randomly assigned to mindfulness training and practice, and the other 23 served as a control group. Although no diets were prescribed, all participants attended one session about the basics of healthy eating and exercise.
The training included nine weekly sessions, each lasting 2 1/2 hours, during which the women learned stress reduction techniques and how to be more aware of their eating by recognizing bodily sensations -- including hunger, fullness and taste satisfaction. At week six they attended an intensive seven-hour, silent meditation retreat.
They were asked to set aside 30 minutes daily for meditation exercises and to practice mindful eating during meals. Researchers used a scientifically tested survey to gauge psychological stress before and after the four-month study, and recorded the women's fat and cortisol levels.
Among women in the treatment group, changes in body awareness, chronic stress, cortisol secretion and abdominal fat were clearly linked. Those who had greater improvements in listening to their bodies' cues, or greater reductions in stress or cortisol, experienced the greatest reductions in abdominal fat.
Among the subset of obese women in the study, those who received the mindfulness training had significant reductions in cortisol after awakening and also maintained their total body weight, compared to women in the waitlist group, who had stable cortisol levels and continued to gain weight.
In a separate, ongoing study with lower-income, pregnant women who are overweight, Epel,Daubenmier and colleagues are teaching similar mindful-eating techniques. Pregnancy is a time when heavy women tend to gain an excessive amount of weight and later find it very hard to lose it. Furthermore, excessive weight gain during pregnancy can harm the baby's health.
"We are intervening at a critical point, when the health of the next generation is being shaped,"Epel said. "We hope to improve the health of both the mothers and their babies."
http://www.sciencedaily.com/releases/2011/12/111207152418.htm