Chronic stress may reduce lifespan in wild baboons, according to new multi-decadal study
Duke University, April 21, 2021
Female baboons may not have bills to pay or deadlines to meet, but their lives are extremely challenging. They face food and water scarcity and must be constantly attuned to predators, illnesses and parasites, all while raising infants and maintaining their social status.
A new study appearing April 21 in Science Advances shows that female baboons with high life-long levels of glucocorticoids, the hormones involved in the 'fight or flight' response, have a greater risk of dying than those with lower levels.
Glucocorticoids are a group of hormones that help prepare the body for a challenge. While these hormones have many functions in the body, persistently high levels of glucocorticoids in the bloodstream can be a marker of stress.
To understand the relationship between stress responses and survival, scientists studied 242 female baboons in Amboseli National Park, in Kenya. For more than 20 years, they measured glucocorticoid levels in the baboons' feces, a task that drew upon one of the world's largest collections of data from a wild primate population.
Females with higher levels of glucocorticoids in their feces, either due to more frequent exposure to different types of challenges, or more intense stress responses, tended to die younger.
The researchers then used these real values of hormone levels and risk of death to simulate a comparison between females that lived at opposite ends of the stress spectrum. The model showed that a hypothetical female whose glucocorticoid levels were kept very elevated would die 5.4 years sooner than a female whose glucocorticoid levels were kept very low.
If they reach adulthood, female baboons have an expected lifespan of about 19 years, so 5.4-years represents a 25% shorter life. Five years more life can also represent enough time to raise one or two more infants.
The team's simulations represent extreme values that are unlikely to be maintained throughout the females' lives, said Fernando Campos, an assistant professor at the University of Texas San Antonio and lead author of the study. Nonetheless, the link between exposure to stress-associated hormones and survival is clear.
"Whether it's due to your environment or your genes or something that we are not measuring, having more glucocorticoids shortens your life," said Susan Alberts, a professor of biology and chair of evolutionary anthropology at Duke and senior author on the paper.
The variation in glucocorticoid levels observed by Campos, Alberts, and their team shows that some females have it worse than others.
Glucocorticoid levels may vary due to environmental factors, such as growing up in very hot and dry years, social factors, such as living in an unusually small or large group, and individual differences, such as being pregnant more often.
"Those are the things we know about," said Alberts, "there's a whole bunch of horrible things that happen to animals that we just can't measure."
"Whatever is exposing you to the glucocorticoids is going to shorten your life," Alberts said. "The more hits you get, the worse your outcome."
Glucocorticoids play all sorts of vital roles in our bodies. They regulate our immunity, help our bodies access energy from sugars and fats, and modulate metabolic reactions to prepare the body for a challenge.
But being constantly prepared for a challenge has high costs: maintenance processes get shut down, and fight or flight processes stay active for longer. Over time, these effects accumulate.
"This chronic activation of the stress response leads to a caustic downstream physiological environment of not enough immune system, and not enough attention to maintenance," said Alberts.
Associations between stress and survival are extremely difficult to test in a natural scenario. They require very frequent data collection for a very long period of time, in this case through the Amboseli Baboon Research Project, which was launched in 1971.
Amboseli females are followed daily from birth to death, their activity is monitored, big events in their lives are recorded, and their feces are periodically collected.
"In my lab we have one of the largest collections of primate behavioral data in the world," said Alberts, "and also one of the biggest primate poop collections." More than 14,000 fecal samples were used in this study.
Poop is a very valuable, if slightly smelly, repository of information. By measuring hormone levels in feces rather than in blood or saliva, researchers avoid handling and stressing the animals, which could influence hormone levels.
"People have long hypothesized that glucocorticoids play a role in how long you live," said Campos, "but to our knowledge this is the first direct evidence that chronic exposure to glucocorticoids strongly predicts survival in wild primates."
Smoking cannabis significantly impairs vision, study finds
Smoking cannabis significantly impairs vision but many users are unaware of it
University of Granada (Spain), April 15, 2021
A study carried out by the University of Granada indicates that smoking cannabis significantly alters key visual functions, such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity
Yet, more than 90% of users believe that using cannabis has no effect on their vision, or only a slight effect
A group of researchers from the Department of Optics of the University of Granada (UGR) has studied the effects of smoking cannabis on various visual parameters compared to the effect that the users themselves perceive the drug to have on their vision.
This study, led by Carolina Ortiz Herrera and Rosario González Anera, has been published in the journal Scientific Reports. Its main author, Sonia Ortiz Peregrina, explains that cannabis use is on the rise despite being an illegal drug. According to the national Survey on Alcohol, Drugs and Other Addictions in Spain 2019-2020, cannabis use nationally has increased since 2011, with 37% of Spanish adults having used this drug at some time. Approximately 10% consumed it in the last year.
In this study, which had the approval of the Human Research Ethics Committee of the UGR (ref. 921/CCEIH/2019), an exhaustive visual trial was conducted on 31 cannabis users, both when they had not consumed any substance in advance and also when they were under the effect of the drug. The researchers also studied the participants' perception of the visual effects of having consumed this drug.
The results showed that, following consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity significantly worsened. Despite this, not all subjects reported a worsening of their vision after smoking cannabis. Indeed, 30% reported that their vision had not suffered at all, while 65% responded that it had worsened only slightly. The authors note that the visual parameter that could be most strongly linked to users' perception of the visual effect is contrast sensitivity.
The study found a negative effect on all of the visual parameters evaluated, with the effect of cannabis on some of the parameters being analysed for the first time in this research. These results, together with the lack of awareness that the participants presented about the visual impairment caused by smoking cannabis, indicate the need to carry out awareness-raising campaigns, as this visual deterioration can pose a danger when performing everyday tasks.
Poor iodine levels in pregnancy poses risks to fetal intellectual development
University of South Australia, April 23, 2021
A growing number of young Australian women are at increased risk of having children born with impaired neurological conditions, due to poor iodine intake.
Dietary changes, including a growing trend towards the avoidance of bread and iodised salt, as well as a reduced intake of animal products containing iodine can contribute to low iodine levels.
A small pilot study undertaken by the University of South Australia (UniSA) comparing iodine levels between 31 vegan/plant-based participants and 26 omnivores has flagged the potential health risk.
Urine samples showed iodine readings of 44 ug/L in the plant-based group, compared to the meat eaters' 64 ug/L level. Neither group came close to the World Health Organization's recommended 100 grams per liter.
Participants from both groups who chose pink or Himalayan salt instead of iodised salt had severely deficient iodine levels, averaging 23 ug/L.
The findings have been published in the International Journal of Environmental Research and Public Health.
While the study was undertaken in South Australia, it builds evidence on a 2017 US study (1) that found nearly two billion people worldwide were iodine deficient, resulting in 50 million experiencing clinical side effects.
UniSA research dietitian Jane Whitbread says adequate iodine is essential for fetal intellectual development.
"Mild to moderate iodine deficiency has been shown to affect language development, memory and mental processing speeds," Ms Whitbread says.
"During pregnancy, the need for iodine is increased and a 150mcg supplement is recommended prior to conception and throughout pregnancy. Unfortunately, most women do not take iodine supplements before conceiving. It is important to consume adequate iodine, especially during the reproductive years."
Dietary sources of iodine include fortified bread, iodized salt, seafoods including seaweeds, eggs, and dairy foods.
Concerns about the link between poor iodine status and impaired neurological conditions in newborns prompted the mandatory fortification of non-organic bread with iodised salt in 2009 in Australia.
It has since been reported that women who consume 100g of iodine-fortified bread every day (approximately three pieces) have five times greater chance of meeting their iodine intake compared to women who don't consume that much. The average amount of bread consumed by women in this study was one piece of bread.
The growing preference of Himalayan salt over iodized table salt may also be problematic, Ms Whitbread says. A quarter of women in the study reported using the pink salt which contains an insignificant level of iodine.
Another issue is that plant-based milks have low levels of iodine and are not currently fortified with this nutrient.
Neither group met the estimated average requirement (EAR) for calcium.
The vegan/plant-based group also did not reach the recommended levels for selenium and B12 without supplementation, but their dietary intake of iron, magnesium, vitamin C, folate and fibre was higher than the meat eaters. This reflects the inclusion of iron-rich soy products, wholemeal foods, legumes, and green leafy vegetables in their diet.
The researchers recommended that both new salts and plant milks be fortified with iodine as well as a campaign to raise awareness about the importance of iodine in the diet, especially for women in their reproductive years.
They also called for a larger study sample to determine iodine status of Australian women.
Taking vitamin D could lower heart disease risk for people with dark skin
Racial disparities in heart disease may be linked to vitamin D deficiency
Penn State University, April 26, 2021
New research suggests a simple step could help millions of people reduce their risk of heart disease: make sure to get enough vitamin D. Elucidating linkages between skin pigmentation, vitamin D and indicators of cardiovascular health, the new study, combined with evidence from previous research, suggests vitamin D deficiency could contribute to the high rate of heart disease among African Americans.
"More darkly-pigmented individuals may be at greater risk of vitamin D deficiency, particularly in areas of relatively low sun exposure or high seasonality of sun exposure," said S. Tony Wolf, PhD, a postdoctoral fellow at the Pennsylvania State University and the study's lead author. "These findings may help to explain some of the differences that we see in the risk for developing blood vessel dysfunction, hypertension and overt cardiovascular disease between ethnic groups in the United States. Although there are many factors that contribute to the development of hypertension and cardiovascular disease, vitamin D supplementation may provide a simple and cost-effective strategy to reduce those disparities."
Wolf noted that the need for vitamin D supplementation depends on a variety of factors, including where you live, how much time you spend in the sun, your skin pigmentation and your age.
Wolf will present the research at the American Physiological Society annual meeting during the Experimental Biology (EB) 2021 meeting, held virtually April 27-30.
Melanin, which is more concentrated in darker skin, is known to inhibit the process our bodies use to make vitamin D in the presence of sunlight. As a result, darkly pigmented people may make less vitamin D, potentially leading to vitamin D deficiency.
For the study, Wolf and colleagues measured skin pigmentation, vitamin D and the activity of nitric oxide in the small blood vessels beneath the skin in 18 heathy adults of varying skin tones. Nitric oxide is important for blood vessel function, and reduced nitric oxide availability is thought to predispose an individual to the development of hypertension or cardiovascular disease. Previous studies suggest vitamin D helps to promote nitric oxide availability.
Study participants with darker skin had lower levels of vitamin D and lower nitric oxide availability. In addition, the researchers found that lower levels of vitamin D were related to reduced nitric oxide-mediated blood vessel function. The results align with those of a separate study by the same research group, which found that vitamin D supplementation improved blood vitamin D levels and nitric oxide-mediated blood vessel function in otherwise healthy, young African American adults.
"Vitamin D supplementation is a simple and safe strategy to ensure vitamin D sufficiency," said Wolf. "Our findings suggest that promoting adequate vitamin D status in young, otherwise healthy adults may improve nitric oxide availability and blood vessel function, and thereby serve as a prophylactic to reduce risk of future development of hypertension or cardiovascular disease."
Men's loneliness linked to an increased risk of cancer
University of Eastern Finland, April 27, 2021
A recent study by the University of Eastern Finland shows that loneliness among middle-aged men is associated with an increased risk of cancer. According to the researchers, taking account of loneliness and social relationships should thus be an important part of comprehensive health care and disease prevention. The findings were published in Psychiatry Research.
"It has been estimated, on the basis of studies carried out in recent years, that loneliness could be as significant a health risk as smoking or overweight. Our findings support the idea that attention should be paid to this issue," Project Researcher Siiri-Liisi Kraav from the University of Eastern Finland says.
The study was launched in the 1980s with 2,570 middle-aged men from eastern Finland participating. Their health and mortality have been monitored on the basis of register data up until present days. During the follow-up, 649 men, i.e. 25% of the participants, developed cancer, and 283 men (11%) died of cancer. Loneliness increased the risk of cancer by about ten per cent. This association with the risk of cancer was observed regardless of age, socio-economic status, lifestyle, sleep quality, depression symptoms, body mass index, heart disease and their risk factors. In addition, cancer mortality was higher in cancer patients who were unmarried, widowed or divorced at baseline.
"Awareness of the health effects of loneliness is constantly increasing. Therefore, it is important to examine, in more detail, the mechanisms by which loneliness causes adverse health effects. This information would enable us to better alleviate loneliness and the harm caused by it, as well as to find optimal ways to target preventive measures."
How exercise and the simple act of moving your body can improve mental health
University of Toronto, April 26, 2021
Whether running around a track or simply stretching in your living room, physical activity can go a long way toward making you happier.
Catherine Sabiston, a professor in the University of Toronto's Faculty of Kinesiology & Physical Education, says the positive impact of exercise on mental health is well-documented.
"There is uncontested evidence that physical activity is conducive to mental health," she says.
For example, Sabiston co-authored a study in the Journal of Sport and Exercise Psychology that adolescents who consistently participated in team sports during high school reported lower depression levels in early adulthood.
A Canada Research Chair in physical activity and mental health, Sabiston directs a lab that studies the connections between physical activity and mental health, developing and evaluating interventions to promote physical activity and mental wellness among people who are at risk of inactivity and mental health problems.
The lab also runs a six-week program called MoveU.HappyU that provides customized coaching and training aimed at reducing the stress and anxiety of students in the lab through physical movement.
She recently spoke with U of T News about why it's important to stay active during the pandemic—and how to feel good doing it.
How closely connected are physical activity and mental health?
Symptoms of mental illness such as anxiety and depression can impede physical activity and vice versa. When you are experiencing symptoms, you may also encounter feelings of low self-worth and an inability to be motivated. It's very hard to find a type of physical activity that you can engage in when you lack interest in most things. Many of the symptoms tied to mental illness are also barriers to physical activity.
On the flip side, there is uncontested evidence that physical activity is conducive to mental health. Physical activity prevents some forms of mental illness, and, for individuals who have been diagnosed with mental illness, physical activity can help reduce those symptoms and improve their quality of life. It holds its own weight in comparison to all other forms of treatment for mental illness, including psychotherapy and even medication.
Physical activity is a potential adjunct to any other form of preventative or treatment-focused therapy.
How exactly does exercise lift our mood?
There are a number of mechanisms at play, including physical activity effects that are tied to our brain activity and brain chemistry. Physical activity increases our body temperature. When we are warmer, we are given the sense that we are comfortable and cared for. Also, from a historical perspective, we know that humans were naturally much more active in the past than we are now. So, physical activity brings us closer to that core level of movement that human bodies are meant to be.
Moreover, physical activity can mimic mental health symptoms such as anxiety. When you exercise, you may sweat or feel your heart racing. That mimics the feeling of panic, so by engaging in exercise, you are producing a similar physical effect that can make you more accustomed to those symptoms. Exercise also provides you with an opportunity, whether for two minutes or 20, to break away from your usual routines or worries. This escape can help people better cope with their symptoms while experiencing a sense of purpose or accomplishment. In fact, feelings of mastery and accomplishment are also specific ways that physical activity impacts mental health. Small goals and activities inherent to physical activity offer plenty of opportunities for positive feedback, feeling successful and achieving, which helps stave off symptoms of mental illness.
Finally, physical activity is something you can partake in outdoors, which has a potentiating effect on mental health. That allows you to see other people, even if you are not interacting with them, and feel a sense of connectedness.
What are some ways people can stay active and motivated during the pandemic?
We want to dispel the myth that physical activity is just running, biking and lifting weights.
Physical activity can be any movement where your heart is increasing its work capacity and your body is moving. In "MoveU.HappyU," we coach students on day-to-day strategies for how to maintain a level of physical activity. Because the program is virtual now, we have trained students who are currently all over the world. Some students who had never spoken to their families about their mental health struggles are now actually having their whole families join in on the physical activities.
The physical activity you are doing should be something that you enjoy. If you don't enjoy it, you're not going to continue to do it.
We also want people to engage in physical activity to improve function rather than appearance. It's important to uncouple the relationship between physical activity for weight and body-size reasons and move towards physical activity for enjoyment and fun reasons. If it's fun, you are more likely to do it, and more likely to do it leads to more benefits.
Do you have any tips for people looking to boost physical activity at home?
There are many ways you can innovate physical activity to make it more varied, even when you are stuck in the same place. The best part of physical activity is thinking about the endless possibilities of ways your body can move. If you are purposeful about it, physical activity can be integrated into your everyday routines:
- Set aside time as you would if you were going to the gym or commuting. Mark it in your calendar or set an alarm to give you an actual reminder.
- Use your phone or a pedometer to measure your step count. Having something that measures how many steps you're taking gives you a baseline: If you know you walked a certain number of steps on day one, you can add five additional steps on day two. That way you'll have a tangible goal for increasing movement.
- Consciously link items or places in your home to short bouts of movement. For example, if you use the toaster oven every morning, make a habit of doing squats while you're waiting for your bread. Or when you are wheeling from one room to another, add some extra distance.
- When you're outside, use aspects of your environment to change up your physical activity. You can change the intensity of your walking or wheeling, for instance, each time that you pass a lamppost or see a blue car. Make it fun to change up the intensity, type, and timing of your activities.
- Create movement challenges for yourself and your friends, family, colleagues, or students. Set goals for taking a certain number of steps or finishing a certain number of arm raises each day. Making physical activity more like a game is a proven strategy for increasing movement—and enjoying it.
