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Especially important for older men need to stay hydrated

Not only does dehydration make our mouths dry and make us want to drink water, it also impacts the regulation of body temperature. When we become dehydrated, we sweat less and, as a result, lose less heat and become less able to cool the body.

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Our ability to regulate body temperature and keep our bodies from becoming dehydrated declines as we get older. New research published today in The Journal of Physiology improves our understanding of the relation between temperature regulation and dehydration.

This research can help us to better tailor strategies for managing both body temperature regulation and hydration during heat exposure in older adults. For example, because of reductions in thirst and our ability to preserve body fluid, as we age, we may require more frequent reminders to drink water during work in the heat or during heatwaves.

Exercise, especially when performed in a hot environment, exposes the body to heat stress, which causes body temperature to increase.

In these situations, we rely on sweating to help remove heat from the body and prevent continued rises in body temperature, which may increase the risk of heat-related illness or injury (such as heat stroke).

However, prolonged sweating can cause too much fluid to be lost from the body. Unless the person drinks water or a sports drink, this can lead to dehydration. Dehydration also reduces the volume of circulating blood and increases the blood’s salt content.

Not only does dehydration make our mouths dry and make us want to drink water, it also impacts the regulation of body temperature. When we become dehydrated, we sweat less and, as a result, lose less heat and become less able to cool the body.

While this can be disadvantageous to regulating body temperature, these adjustments limit further fluid losses and slow the rate of dehydration. Thus, our body’s response to dehydration acts to balance the body’s fluid and temperature regulatory needs.

Until recently, however, our understanding of the effects of dehydration on body temperature regulation came primarily from studies conducted in young adults.

Dehydration did not reduce heat loss or increase body temperature in the older adults during exercise. At first glance this seems like a beneficial response. However, this meant that the older adults did not attempt to adjust the rate of sweat loss to prevent further dehydration. As a result, they experienced greater strain on the heart as evidenced by a more pronounced increase in heart rate compared to younger men.

Previous literature indicates that as we age, our body responds less efficiently to dehydration, and some have suggested that this is due to an impaired ability of the body to ‘sense’ increases in salt levels in the blood (i.e. lack of water) that would normally trigger thirst and drinking.

Since the reduction in sweat rate during dehydration is beneficial for reducing fluid loss, researchers at the Human and Environmental Physiology Research Unit at the University of Ottawa reasoned that a reduced sensitivity to elevated blood osmolality (which is a measure of the bloods saltiness) may also explain the blunted effect of dehydration on heat loss and body temperature regulation in older adults during exercise in the heat.

To evaluate this hypothesis, the research group had young and older men perform exercise in the heat. Before exercise, blood salt content was increased artificially by giving them infusions of saline (salt water).

The participants performed the exercise in a device called a whole-body direct calorimeter, which precisely tracks the amount of heat lost from the entire body, which is caused by increases in sweating and blood flow to the skin.

The primary finding of the study was that, in contrast to young adults, the regulation of body temperature in the older adults was not influenced by increases in the saltiness of the blood.

Less efficient regulation of body temperature and hydration status are thought to contribute to the increased risk of mild (e.g. heat exhaustion) and severe (e.g., heat stroke) heat-related injuries as well as adverse heart problems experienced by older adults during heat stress, such as during occupational work in the heat (e.g., electrical utilities, construction) or in their homes/communities during heatwaves.

Since the young and older adults were physically active without any overt chronic health conditions it is difficult to know whether our findings translate to more sedentary individuals or those with common age-related chronic diseases such as Type 2 diabetes.

Commenting on the study, first author Robert Meade said: “Given that common age-related chronic health conditions such as type-2 diabetes are associated with less efficient regulation of body temperature and hydration status, future research should be conducted to see whether our findings translate to or are exaggerated in those populations. While our research design allowed us to test the independent effect of osmolality on heat loss, the effect of reduced blood volume (termed hypovolemia) on sweating in older adults is currently unknown.”

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Allergy season starts earlier each year due to climate change and pollen transport

Allergy sufferers are no strangers to problems with pollen. But now – due to climate change – the pollen season is lasting longer and starting earlier than ever before, meaning more days of itchy eyes and runny noses. Warmer temperatures cause flowers to bloom earlier, while higher CO2 levels cause more pollen to be produced.

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Photo by Coley Christine from Unsplash.com

Allergy sufferers are no strangers to problems with pollen. But now – due to climate change – the pollen season is lasting longer and starting earlier than ever before, meaning more days of itchy eyes and runny noses. Warmer temperatures cause flowers to bloom earlier, while higher CO2 levels cause more pollen to be produced.

The effects of climate change on the pollen season have been studied at-length, and according to some scientists, has grown by as much as 20 days in the past 30 years, at least in the US and Canada. But one important element is often overlooked – “Pollen is meant to fly,” says Dr Annette Menzel, Professor of ecoclimatology at the Technical University of Munich. “Transport phenomena have to be taken into account.”

Along with her colleagues, she studied the transport of pollen in Bavaria, Germany, in order to better understand how the pollen season has changed over time. “The transport of pollen has important implications for the length, timing, and severity of the allergenic pollen season,” says Dr Ye Yuan, a coauthor on the study.

Menzel and her team focused on Bavaria – a state in southeast Germany – and used six pollen monitoring stations scattered around the region to analyze data. Their results were recently published in Frontiers in Allergy. They found that certain species of pollen, such as from hazel shrubs and alder trees, advanced the start of their seasons by up to 2 days per year, over a period of 30 years (between 1987 and 2017). Other species, which tend to bloom later in the year, such as birch and ash trees, moved their seasons 0.5 days earlier on average each year, across that same time period.

Pollen can travel hundreds of kilometers and, with changing weather patterns and altered species distributions, it’s possible that people are becoming exposed to “new” pollen species – meaning pollen that our bodies are unaccustomed to encountering each year.

While it can sometimes be difficult to differentiate between local and transported pollen, the researchers focused on pre-season transports. So, for example, if pollen from birch trees was present at the monitoring station, but local birch trees would not flower for at least another 10 days, that pollen was considered to be transported from far away.

“We were surprised that pre-season pollen transport is a quite common phenomenon being observed in two-thirds of the cases,” says Menzel. As for why it’s important to understand how much pollen is from far away, Yuan says that: “Especially for light-weight allergenic [pollen], long distance transport could seriously influence local human health.”

By examining another element besides simple pollen concentration, scientists can delve deeper into how exactly the pollen season is being affected by climate change. For example, Menzel says that the pollen season may be even longer than estimated based on flowering observations by “taking into account pollen transport, as it has been done in our current study.”

While the Munich study did not track how far pollen was transported, and only differentiated between local and long-range transport (meaning pollen coming from outside Bavaria), it provides a crucial key in our understanding of annual pollen patterns. Yuan says that future studies should account for “climate change scenarios [and] land use/land cover changes.” He also adds that citizen scientists may be able to contribute to pollen studies, who can help collect local observations and contribute to data collection.

It doesn’t look like the pollen season will shorten any time soon, but more research on the subject can provide a better understanding of global patterns and changes so that we can better address these issues in the future.

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Women better at reading minds than men – study

Mind-reading, sometimes referred to in psychology as ‘mentalising’, is an important ability enabling us to pick-up on subtle behavioural cues that might indicate that someone we are speaking to is thinking something that they are not saying (e.g. being sarcastic or even lying).

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Psychologists at the University of Bath, Cardiff, and London have developed the first ever ‘mind-reading questionnaire’ to assess how well people understand what others are really thinking.

A new approach to ‘mind-reading’ has been developed by researchers at the University of Bath, Cardiff, and London to improve how well we understand what others are thinking. And it transpires that women are much better than men at putting themselves in someone else’s shoes.

Mind-reading, sometimes referred to in psychology as ‘mentalising’, is an important ability enabling us to pick-up on subtle behavioural cues that might indicate that someone we are speaking to is thinking something that they are not saying (e.g. being sarcastic or even lying).

The researchers say that we all have different mind-reading abilities, with some of us inherently better than others. The fact that not all of us are good at mind-reading can cause challenges – in particular for people with autism where it can lead to social struggles in building or maintaining relationships.

To identify those people who have difficulties and to provide them with appropriate support, the team at Bath designed a new mind-reading test, which draws on data from over 4,000 autistic and non-autistic people in the UK and US.

Results from their simple, four-step questionnaire were scored, ranging from 4 to 16 (with 4 indicating poor mind-reading abilities; 16 indicating excellent abilities). The average score for their questionnaire was between 12 and 13. After statistically confirming that the test was measuring the same thing in men and women, they found that females reported better mind-reading than males, whilst also confirming some of the well-reported social challenges faced by the autistic community.

Their method, which uses just four questions to assess individuals, is published in the journal Psychological Assessment.

Dr Punit Shah, senior author of the study and leading expert on social cognitive processing at the University of Bath’s Department of Psychology explained: “We will all undoubtedly have had experiences where we have felt we have not connected with other people we are talking to, where we’ve perceived that they have failed to understand us, or where things we’ve said have been taken the wrong way. Much of how we communicate relies on our understanding of what others are thinking, yet this is a surprisingly complex process that not everyone can do.

“To understand this psychological process, we needed to separate mind-reading from empathy. Mind-reading refers to understanding what other people are thinking, whereas empathy is all about understanding what others are feeling. The difference might seem subtle but is critically important and involves very different brain networks. By focussing carefully on measuring mind-reading, without confusing it with empathy, we are confident that we have just measured mind-reading. And, when doing this, we consistently find that females reported greater mind-reading abilities than their male counterparts.”

Lead researcher, Rachel Clutterbuck, emphasised the clinical importance of the questionnaire. She said: “This new test, which takes under a minute to complete, has important utility in clinical settings. It is not always obvious if someone is experiencing difficulties understanding and responding to others – and many people have learnt techniques which can reduce the appearance of social difficulties, even though these remain.

“This work has great potential to better understand the lived experience of people with mind-reading difficulties, such as those with autism, whilst producing a precise quantitative score that may be used by clinicians to identify individuals who may benefit from interventions.”

Dr Shah added: “This research has been about understanding more about our mind-reading abilities and providing solutions to those who might struggle, particularly the autistic community. We have created a freely available questionnaire which we hope can help identify people who are experiencing mental difficulties relevant to social situations.”

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Acid reflux disease may increase risk of cancers of the larynx and esophagus

Results from a large prospective study indicate that gastroesophageal reflux disease (GERD), which also causes heartburn symptoms, is linked with higher risks of various cancers of the larynx (or voice box) and esophagus.

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Results from a large prospective study indicate that gastroesophageal reflux disease (GERD), which also causes heartburn symptoms, is linked with higher risks of various cancers of the larynx (or voice box) and esophagus. The study is published in CANCER, a peer-reviewed journal of the American Cancer Society.

GERD, a gastrointestinal disorder that affects approximately 20 percent of U.S. adults, occurs when stomach acid flows back into the esophagus, where it can cause tissue damage. Research indicates that this damage may put patients at risk of developing a type of cancer called esophageal adenocarcinoma.

To provide additional insights concerning this link and potential links to other types of cancer, a team led by Christian C. Abnet, PhD, of the National Cancer Institute, part of the National Institutes of Health (NIH), examined information on 490,605 adults enrolled in the NIH-AARP Diet and Health Study, a prospective study that mailed questionnaires in 1995-1996 to 3.5 million AARP members, aged between 50 and 71 years who were living in California, Florida, Louisiana, New Jersey, North Carolina, or Pennsylvania, or in the metropolitan areas of Atlanta, Georgia, and Detroit, Michigan.

Using Medicare claims data, the investigators estimated that 24 percent of participants had a history of GERD. Over the following 16 years after participants joined the study, 931 patients developed esophageal adenocarcinoma, 876 developed laryngeal squamous cell carcinoma, and 301 developed esophageal squamous cell carcinoma. People with GERD had about a two-times higher risk of developing each of these types of cancer, and the elevated risk was similar across groups categorized by sex, smoking status, and alcohol consumption. The investigators were able to replicate the results when they restricted analyses to the Medicare data subset of 107,258 adults.

The team estimated that approximately 17 percent of these cancers in the larynx and esophagus are associated with GERD.

“This study alone is not sufficient to result in specific actions by the public. Additional research is needed to replicate these findings and establish GERD as a risk factor for cancer and other diseases,” said Dr. Abnet. “Future studies are needed to evaluate whether treatments aimed at GERD symptoms will alter the apparent risks.”

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