Adult Health Habits Influence How Much We Shrink With Age

Apr. 1, 2013 —
Science Daily/University of Southern California
Even if you didn't eat your veggies or drink your milk as a child, your height is still in your hands, reveal new findings by economists from the University of Southern California, Harvard University and Peking University.

Using unique data from a new massive longitudinal survey of 17,708 adults beginning at age 45, the researchers show for the first time that lifestyle choices we make in adulthood -- and not just the hand we're dealt as children -- influence how tall we stand as we age.

"Had we only examined the correlations between measured height and health, we would have missed this important insight," said John Strauss, professor of economics at USC, and an investigator on a study published in the April 2013 issue of the American Economic Journal: Applied Economics. "The evidence shows that it is not only early-life events that are associated with how we age, but health decisions in later life as well."

While prior work has looked for the connection between height and health -- both in childhood and adulthood -- the researchers are the first to examine height loss as we age. They show that regardless of your maximum height, the loss of height over time is also an important indicator for other health issues as we age.

For example, the research reveals an especially strong relationship between height loss and cognitive health. Those who had lost more height were also much more likely to perform poorly on standard tests of cognitive health such as short-term memory, ability to perform basic arithmetic and awareness of the date.

Among the socioeconomic factors that correlate to height loss, urban dwellers had much less height loss than those in rural areas, the researchers found, in a country where there has been significant migration to urban areas in the last few decades. In addition, having completed primary school, rather than being illiterate, is associated with 0.9 cm less height shrinkage in men -- a large difference when considering that overall average height loss for men is 3.3 cm. Completing high school meant an additional 1 cm less in shrinkage.

For women, having completed primary school was the difference in 0.6 cm of shrinkage, compared to average overall height decrease of 3.8 cm.

"Height has been recognized as an acceptable proxy for childhood health conditions, but there are complications there," says USC economist Geert Ridder, a co-investigator on the study. "Some of adult health might be determined by childhood circumstances, but people shrink differentially, and that shrinkage is also a measure of adult health conditions."

All humans go through physical changes with age, including an increase in body fat and decrease in bone mass. But a decrease in height can be further exacerbated by certain kinds of arthritis, inflammation of spine joints or osteoporosis, which other studies have shown are associated with such lifestyle choices as diet, exercise and smoking.

The researchers used new data from the China Health and Retirement Longitudinal Study, a groundbreaking sampling project led by USC economist Strauss, Yaohui Zhao of the China Center for Economic Research (CCER) at Peking University and Gonghuan Yang of the Chinese Academy of Medical Sciences and Peking Union Medical College, that covers 150 counties randomly chosen throughout China.

The baseline for the survey was collected from June 2011 to March 2012 and includes both subjective self-reported responses to survey questions as well as objective physical measurements such as blood tests. These physical measurements and personal interviews will be followed-up with the same 17,708 people every two years -- capturing, for the first time, critical data about human aging in the most populous and most rapidly aging country in the world.

For example, recent changes in social security policy and health insurance in China provide a valuable opportunity for researchers to study how health care actually affects health and aging in a large population, with insights for other developing health care systems worldwide, as well as an opportunity to identify possible under-diagnosis of various chronic conditions.

The researchers will also be able to examine the role specific historical events in China may have had on long-term health, including whether there are health and aging differences among those who were "sent-down" during the Cultural Revolution.

The baseline CHARLS data is publicly available to researchers at http://charls.ccer.edu.cn. The research is supported by the National Institute of Aging, the China Natural Science Foundation, the Fogarty International Center of the National Institutes of Health and the World Bank.

To estimate full adult height for older study participants, the researchers examined relationships between current height and the length of limbs, which do not shrink with age, from younger survey participants who have not yet started shrinking.
http://www.sciencedaily.com/releases/2013/04/130401101017.htm

Decreased Melatonin Secretion: Risk of Developing Type 2 Diabetes

Apr. 2, 2013 —

Science Daily/American Medical Association (AMA)

With previous evidence suggesting that melatonin may have a role in glucose metabolism, researchers have found an independent association between decreased secretion of melatonin and an increased risk for the development of type 2 diabetes, according to a study in the April 3 issue of JAMA.

"Melatonin receptors have been found throughout the body in many tissues including pancreatic islet cells, reflecting the widespread effects of melatonin on physiological functions such as energy metabolism and the regulation of body weight," according to background information in the article. "Loss-of-function mutations in the melatonin receptor are associated with insulin resistance and type 2 diabetes. Additionally, in a cross-sectional analysis of persons without diabetes, lower nocturnal melatonin secretion was associated with increased insulin resistance." A prospective association between melatonin secretion and type 2 diabetes has not been previously reported.

Ciaran J. McMullan, M.D., of Brigham and Women's Hospital, Boston, and colleagues conducted a study to investigate the association of melatonin secretion and the incidence of type 2 diabetes. The analysis consisted of a case-control study nested within the Nurses' Health Study cohort. Among participants without diabetes who provided urine and blood samples at baseline in 2000, the researchers identified 370 women who developed type 2 diabetes from 2000-2012 and matched 370 controls. Statistical analyses for determining associations between melatonin secretion at baseline and incidence of type 2 diabetes included controlling for demographic characteristics, lifestyle habits, measures of sleep quality, and biomarkers of inflammation and endothelial dysfunction.

Secretion of melatonin varied widely among participants in the study; the median (midpoint) urinary ratio of 6-sulfatoxymelatonin to creatinine was 67.0 ng/mg in the highest category compared with 14.4 ng/mg in the lowest category. The median ratio was significantly higher among controls (36.3 ng/mg) than among cases (28.2 ng/mg). Insulin sensitivity was higher among women with higher urinary ratios of 6-sulfatoxymelatonin to creatinine.

The researchers found that after controlling for body mass index and other lifestyle factors, menopausal status, family history of diabetes, history of hypertension, use of beta-blockers or non-steroidal anti-inflammatory drugs, region of the United States, and plasma biomarkers of diabetes risk, participants in the lowest category of urinary ratio of 6-sulfatoxymelatonin to creatinine had a 2.2 times higher odds of developing type 2 diabetes compared to participants in the highest category.

Women in the lowest category of melatonin secretion had an estimated diabetes incidence rate that was more than double that of women in the highest category (as measured by cases per 1,000 person-years).

"It is interesting to postulate from these data, in combination with prior literature, whether there is a causal role for reduced melatonin secretion in diabetes risk. Further studies are needed to determine whether increasing melatonin levels (endogenously via prolonged nighttime dark exposure or exogenously via supplementation) can increase insulin sensitivity and decrease the incidence of type 2 diabetes," the authors conclude.

http://www.sciencedaily.com/releases/2013/04/130402162420.htm

Fetal Exposure to Excessive Stress Hormones Linked to Adult Mood Disorders

Apr. 6, 2013 —

Science Daily/British Neuroscience Association

Exposure of the developing fetus to excessive levels of stress hormones in the womb can cause mood disorders in later life and now, for the first time, researchers have found a mechanism that may underpin this process, according to research presented April 7 at the British Neuroscience Association Festival of Neuroscience (BNA2013) in London.

Adverse environments experienced while in the womb, such as in cases of stress, bereavement or abuse, will increase levels of glucocorticoids in the mother, which may harm the growing baby. Glucocorticoids are naturally produced hormones and they are also known as stress hormones because of their role in the stress response.

"The stress hormone cortisol may be a key factor in programming the fetus, baby or child to be at risk of disease in later life. Cortisol causes reduced growth and modifies the timing of tissue development as well as having long lasting effects on gene expression," she will say.

Puberty is another sensitive time of development and stress experienced at this time can also be involved in programming adult mood disorders. Prof Holmes and her colleagues have found evidence from imaging studies in rats that stress in early teenage years could affect mood and emotional behaviour via changes in the brain's neural networks associated with emotional processing.

Prof Holmes will say: "We showed that in stressed 'teenage' rats, the part of the brain region involved in emotion and fear (known as amygdala) was activated in an exaggerated fashion when compared to controls. The results from this study clearly showed that altered emotional processing occurs in the amygdala in response to stress during this crucial period of development."

http://www.sciencedaily.com/releases/2013/04/130407090835.htm

Brain's Stress Circuits Undergo Profound Learning Early in Life

Apr. 7, 2013 —
Science Daily/University of California – Berkeley
https://www.sciencedaily.com/images/2013/04/130416204546_1_540x360.jpg
Brain cells called astrocytes (pink) appear to be key players in the response to acute stress. Stress hormones stimulate astrocytes to release fibroblast growth factor 2 (green), which in turn lead to new neurons (blue).
Credit: Image by Daniela Kaufer & Liz Kirby

Overworked and stressed out? Look on the bright side. Some stress is good for you.

"You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley. "Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance."

New research by Kaufer and UC Berkeley post-doctoral fellow Elizabeth Kirby has uncovered exactly how acute stress -- short-lived, not chronic -- primes the brain for improved performance.

In studies on rats, they found that significant, but brief stressful events caused stem cells in their brains to proliferate into new nerve cells that, when mature two weeks later, improved the rats' mental performance.

"I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert," she said.

Kaufer, Kirby and their colleagues in UC Berkeley's Helen Wills Neuroscience Institute describe their results in a paper published April 16 in the new open access online journal eLife.

The UC Berkeley researchers' findings, "in general, reinforce the notion that stress hormones help an animal adapt -- after all, remembering the place where something stressful happened is beneficial to deal with future situations in the same place," said Bruce McEwen, head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at The Rockefeller University, who was not involved in the study.

Kaufer is especially interested in how both acute and chronic stress affect memory, and since the brain's hippocampus is critical to memory, she and her colleagues focused on the effects of stress on neural stem cells in the hippocampus of the adult rat brain. Neural stem cells are a sort of generic or progenitor brain cell that, depending on chemical triggers, can mature into neurons, astrocytes or other cells in the brain. The dentate gyrus of the hippocampus is one of only two areas in the brain that generate new brain cells in adults, and is highly sensitive to glucocorticoid stress hormones, Kaufer said.

Much research has demonstrated that chronic stress elevates levels of glucocorticoid stress hormones, which suppresses the production of new neurons in the hippocampus, impairing memory. This is in addition to the effect that chronically elevated levels of stress hormones have on the entire body, such as increasing the risk of chronic obesity, heart disease and depression.

Less is known about the effects of acute stress, Kaufer said, and studies have been conflicting.

To clear up the confusion, Kirby subjected rats to what, to them, is acute but short-lived stress -- immobilization in their cages for a few hours. This led to stress hormone (corticosterone) levels as high as those from chronic stress, though for only a few hours. The stress doubled the proliferation of new brain cells in the hippocampus, specifically in the dorsal dentate gyrus.

Kirby discovered that the stressed rats performed better on a memory test two weeks after the stressful event, but not two days after the event. Using special cell labeling techniques, the researchers established that the new nerve cells triggered by the acute stress were the same ones involved in learning new tasks two weeks later.

"In terms of survival, the nerve cell proliferation doesn't help you immediately after the stress, because it takes time for the cells to become mature, functioning neurons," Kaufer said. "But in the natural environment, where acute stress happens on a regular basis, it will keep the animal more alert, more attuned to the environment and to what actually is a threat or not a threat."

They also found that nerve cell proliferation after acute stress was triggered by the release of a protein, fibroblast growth factor 2 (FGF2), by astrocytes -- brain cells formerly thought of as support cells, but that now appear to play a more critical role in regulating neurons.

"The FGF2 involvement is interesting, because FGF2 deficiency is associated with depressive-like behaviors in animals and is linked to depression in humans," McEwen said.

Kaufer noted that exposure to acute, intense stress can sometimes be harmful, leading, for example, to post-traumatic stress disorder. Further research could help to identify the factors that determine whether a response to stress is good or bad.

"I think the ultimate message is an optimistic one," she concluded. "Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it."

The eLife paper was coauthored by UC Berkeley colleagues Sandra E Muroy, Wayne G. Sun and David Covarrubias of the Department of Molecular and Cell Biology; Megan J. Leong of the Helen Wills Neuroscience Institute; and Laurel A. Barchas of the Department of Integrative Biology. Kirby is now a post-doctoral fellow at Stanford University.

Kaufer's research was funded by a BRAINS (Biobehavioral Research Awards for Innovative New Scientists) award from the National Institute of Mental Health of the National Institutes of Health (R01 MH087495) and the National Alliance for Research on Schizophrenia and Depression. Kirby was supported by fellowships from the California Institute for Regenerative Medicine and the U.S. Department of Defense.
http://www.sciencedaily.com/releases/2013/04/130407133314.htm

Acute Stress Primes Brain for Better Cognitive and Mental Performance

Apr. 16, 2013 —
Science Daily/University of California - Berkeley
https://www.sciencedaily.com/images/2013/04/130416204546_1_540x360.jpg
Brain cells called astrocytes (pink) appear to be key players in the response to acute stress. Stress hormones stimulate astrocytes to release fibroblast growth factor 2 (green), which in turn lead to new neurons (blue).
Credit: Image by Daniela Kaufer & Liz Kirby

Overworked and stressed out? Look on the bright side. Some stress is good for you. "You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley. "Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance."

New research by Kaufer and UC Berkeley post-doctoral fellow Elizabeth Kirby has uncovered exactly how acute stress -- short-lived, not chronic -- primes the brain for improved performance.

Kaufer noted that exposure to acute, intense stress can sometimes be harmful, leading, for example, to post-traumatic stress disorder. Further research could help to identify the factors that determine whether a response to stress is good or bad. "I think the ultimate message is an optimistic one," she concluded. "Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it."
http://www.sciencedaily.com/releases/2013/04/130416204546.htm

Social Stress and the Inflamed Brain

Apr. 21, 2013 —

Science Daily/Federation of American Societies for Experimental Biology

Depression is the leading cause of disability with more than 350 million people globally affected by this disease. In addition to debilitating consequences on mental health, depression predisposes an individual to physiological disease such as heart disease, and conversely heart disease increases the risk of depression.

According to the World Health Organization by the year 2020 heart disease and depression will be the number one and number two leading causes of disability in developed countries. While the co-occurrence of these disorders is well recognized, an understanding of the underlying mechanisms that lead to this relationship are lacking.

The identification of factors in the brain that distinguish susceptibility and resiliency to depression and heart disease comorbidity would be a major advance in predicting, preventing and treating these disorders. Dr. Wood is continuing these studies as an Assistant Professor at the University of South Carolina School of Medicine with the hope that these findings will uncover new targets to treat the mind and body.

http://www.sciencedaily.com/releases/2013/04/130421153839.htm

Cutting Back On Sleep Harms Blood Vessel Function and Breathing Control

Apr. 22, 2013 —
Science Daily/American Physiological Society (APS)
With work and entertainment operating around the clock in our modern society, sleep is often a casualty. A bevy of research has shown a link between sleep deprivation and cardiovascular disease, metabolic disorders, and obesity. However, it's been unclear why sleep loss might lead to these effects. Several studies have tested the effects of total sleep deprivation, but this model isn't a good fit for the way most people lose sleep, with a few hours here and there. In a new study by Keith Pugh, Shahrad Taheri, and George Balanos, all of the University of Birmingham in the United Kingdom, researchers test the effects of partial sleep deprivation on blood vessels and breathing control. They find that reducing sleep length over two consecutive nights leads to less healthy vascular function and impaired breathing control.

Cutting Sleep in Half The researchers have worked with eight healthy adult volunteers between the ages of 20 to 35 to date. For the first two nights of the study, the researchers had these volunteers sleep a normal night of eight hours. Then, rather than restrict their sleep completely, the researchers instead had them sleep only four hours during each of three consecutive nights.

Each of these volunteers underwent tests to see how well their blood vessels accommodate an increase in blood flow, a test of healthy blood vessel, or vascular, function. Following the first two nights of restricted sleep, the researchers found a significant reduction in vascular function compared to following the nights of normal sleep. However, after the third night of sleep restriction, vascular function returned to baseline, possibly an adaptive response to acute sleep loss, study leader Pugh explains.

In other tests, the researchers exposed subjects to moderately high levels of carbon dioxide, which normally increases the depth and rate of breathing. However, breathing control was substantially reduced after the volunteers lost sleep.

The researchers later had these volunteers sleep 10 hours a night for five nights. After completing the same tests, results showed that vascular function and breathing control had improved.

A Mechanism for Cardiovascular Harm Pugh notes that the results could suggest a mechanism behind the connection between sleep loss and cardiovascular disease. "If acute sleep loss occurs repetitively over a long period of time, then vascular health could be compromised further and eventually mediate the development of cardiovascular disease," he explains.

Similarly, the loss of breathing control that the researchers observed could play a role in the development of sleep apnea, which has also been linked with cardiovascular disease. Pugh adds that some populations who tend to report sleeping shorter periods, such as the elderly, could be at an even higher risk of these adverse health effects.

He and his colleagues plan to continue studying these effects in more subjects to strengthen their results. Eventually, Pugh says, they hope to discover a mechanism to explain why restricting sleep harms vascular function and breathing control.
http://www.sciencedaily.com/releases/2013/04/130422102026.htm

Getting a Grip On Sleep

May 14, 2013 —
Science Daily/RIKEN
All mammals sleep, as do birds and some insects. However, how this basic function is regulated by the brain remains unclear. According to a new study by researchers from the RIKEN Brain Science Institute, a brain region called the lateral habenula plays a central role in the regulation of REM sleep. In an article published today in the Journal of Neuroscience, the team shows that the lateral habenula maintains and regulates REM sleep in rats through regulation of the serotonin system.

“Our results indicate that the lateral habenula is essential for maintaining theta rhythms in the hippocampus, which characterize REM sleep in the rat, and that this is done via serotonergic modulation,” concludes Dr Aizawa. “This study reveals a novel role of the lateral habenula, linking serotonin and REM sleep, which suggests that an hyperactive habenula in patients with depression may cause altered REM sleep,” add the authors.
http://www.sciencedaily.com/releases/2013/05/130514184514.htm

Light Therapy Improves Sleep and Promote Recovery in Patients With Mild TBI

May 31, 2013 —

Science Daily/American Academy of Sleep Medicine

A new study suggests that bright light therapy may improve sleep, cognition, emotion and brain function following mild traumatic brain injury (TBI).

Results show that six weeks of morning bright light therapy resulted in a marked decrease in subjective daytime sleepiness. This improvement was further associated with improvements in the propensity to fall asleep and nighttime sleep quality. Bright light therapy also affected depressive symptoms.

"Our preliminary data suggests that morning bright light therapy might be helpful to reduce subjective daytime sleepiness and to improve nighttime sleep," said investigator Mareen Weber, PhD, instructor in psychiatry at McLean Hospital/Harvard Medical School in Belmont, Mass. "Importantly, the research also shows changes in brain activation during a demanding cognitive task, suggesting that bright light treatment might yield changes in brain functioning."

The research abstract was published recently in an online supplement of the journal SLEEP, and Weber will present the findings Monday, June 3, in Baltimore, Md., at SLEEP 2013, the 27th annual meeting of the Associated Professional Sleep Societies LLC.

The study group comprised 18 individuals with a documented history of at least one mild TBI and sleep disturbance that either emerged or was aggravated with the most recent injury. Data were gathered using Multiple Sleep Latency Tests (MSLT), actigraphy and sleep diaries, and all participants underwent magnetic resonance imaging (MRI) and comprehensive psychiatric and neuropsychological assessments before and after the intervention.

According to the authors, it has been estimated that at least 50 percent of individuals with TBI experience some kind of sleep disturbance at some point following their injury, and sleep has been demonstrated to be essential for brain plasticity and may be important for recovery.

"Improving sleep following mild traumatic brain injury could prove critical to maximizing recovery from the injury," said Weber. "Furthermore, bright light therapy is easy and minimally invasive, requiring no medication, and has no known serious side effects."

http://www.sciencedaily.com/releases/2013/05/130531105518.htm

Blood Vessels in the Eye Linked With IQ, Cognitive Function

June 3, 2013 —

Science Daily/Association for Psychological Science

https://www.sciencedaily.com/images/2013/06/130603135533_1_540x360.jpg

Eye exam. The width of blood vessels in the retina, located at the back of the eye, may indicate brain health years before the onset of dementia and other deficits.

Credit: © lightpoet / Fotolia

The width of blood vessels in the retina, located at the back of the eye, may indicate brain health years before the onset of dementia and other deficits, according to a new study published in Psychological Science, a journal of the Association for Psychological Science.

Research shows that younger people who score low on intelligence tests, such as IQ, tend to be at higher risk for poorer health and shorter lifespan, but factors like socioeconomic status and health behaviors don't fully account for the relationship.

The findings suggest that the processes linking vascular health and cognitive functioning begin much earlier than previously assumed, years before the onset of dementia and other age-related declines in brain functioning.

"Digital retinal imaging is a tool that is being used today mainly by eye doctors to study diseases of the eye," Shalev notes. "But our initial findings indicate that it may be a useful investigative tool for psychological scientists who want to study the link between intelligence and health across the lifespan."

http://www.sciencedaily.com/releases/2013/06/130603135533.htm

Are Smartphones Disrupting Your Sleep?

June 3, 2013 —

Science Daily/Mayo Clinic

Smartphones and tablets can make for sleep-disrupting bedfellows. One cause is believed to be the bright light-emitting diodes that allow the use of mobile devices in dimly lit rooms; the light exposure can interfere with melatonin, a hormone that helps control the natural sleep-wake cycle. But there may be a way to check your mobile device in bed and still get a good night's sleep. A Mayo Clinic study suggests dimming the smartphone or tablet brightness settings and holding the device at least 14 inches from your face while using it will reduce its potential to interfere with melatonin and impede sleep.

"There's a lot of concern about using mobile devices and that prompted me to wonder, are they always a negative factor for sleep?" Dr. Krahn says. "We found that only at the highest setting was the light over a conservative threshold that might affect melatonin levels. If it's at the mid setting or at a low setting it's bright enough to use."

http://www.sciencedaily.com/releases/2013/06/130603163610.htm

Getting Enough Sleep Could Help Prevent Type 2 Diabetes

June 18, 2013 —

Science Daily/Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed)

Men who lose sleep during the work week may be able to lower their risk of developing Type 2 diabetes by getting more hours of sleep, according to Los Angeles Biomedical Research Institute (LA BioMed) research findings presented today at The Endocrine Society's 95th Annual Meeting in San Francisco.

"We all know we need to get adequate sleep, but that is often impossible because of work demands and busy lifestyles," said Dr. Liu. "Our study found extending the hours of sleep can improve the body's use of insulin, thereby reducing the risk of Type 2 diabetes in adult men. Reducing the incidence of this chronic illness is critical for a nation where diabetes affects nearly 26 million people and costs an estimated $174 billion annually."

"The good news is that by extending the hours they sleep, adult men -- who over a long period of time do not get enough sleep during the working week -- can still improve their insulin sensitivity," Liu said

http://www.sciencedaily.com/releases/2013/06/130618131848.htm

Stress Hormone Could Trigger Mechanism for the Onset of Alzheimer's

June 19, 2013 —

Science Daily/Temple University

 A chemical hormone released in the body as a reaction to stress could be a key trigger of the mechanism for the late onset of Alzheimer's disease, according to a study by researchers at Temple University.

"Stress is an environmental factor that looks like it may play a very important role in the onset of Alzheimer's disease," said Domenico Praticò, professor of pharmacology and microbiology and immunology in Temple's School of Medicine, who led the study. "When the levels of corticosteroid are too high for too long, they can damage or cause the death of neuronal cells, which are very important for learning and memory."

http://www.sciencedaily.com/releases/2013/06/130619102605.htm