Desk-based jobs may offer protection against poor cognition in later life

UNIVERSITY OF CAMBRIDGE

People who work in jobs that require less physical activity - typically office and desk-based jobs - are at a lower risk of subsequent poor cognition than those whose work is more physically active, suggests new research from the University of Cambridge.

Lack of physical activity and exercise are known risk factors for major health conditions, including cognitive impairments such as memory and concentration problems. However, evidence as to whether physical activity actually protects against cognitive decline has often been mixed and inconclusive.

Researchers at the University of Cambridge examined patterns of physical activity among 8,500 men and women who were aged 40-79 years old at the start of the study and who had a wide range of socioeconomic backgrounds and educational attainment. The individuals were all part of the EPIC-Norfolk Cohort. In particular, the team were able to separate physical activity during work and leisure to see if these had different associations with later life cognition.

"The often used mantra 'what is good for the heart, is good for the brain' makes complete sense, but the evidence on what we need to do as individuals can be confusing," said Shabina Hayat from the Department of Public Health and Primary Care at the University of Cambridge. "With our large cohort of volunteers, we were able to explore the relationship between different types of physical activity in a variety of settings."

As part of the study, participants completed a health and lifestyle questionnaire, including information on the level of physical activity during both work and leisure, and underwent a health examination. After an average 12 years, the volunteers were invited back and completed a battery of tests that measured aspects of their cognition, including memory, attention, visual processing speed and a reading ability test that approximates IQ.

While many studies have only been able to report cross-sectional findings, the ability to follow up EPIC-Norfolk participants over a long period allowed the researchers to examine data prospectively. This helped them rule out any bias resulting from people with poor cognition - possibly as a result of cognitive impairment or early dementia - being less likely to be physically active due to poor cognition, rather than poor cognition being a result of physical inactivity.

Among their findings, published today in the International Journal of Epidemiology, the researchers report:

• Individuals with no qualifications were more likely to have physically active jobs, but less likely to be physically active outside of work.
• A physically inactive job (typically a desk-job), is associated with lower risk of poor cognition, irrespective of the level of education. Those who remained in this type of work throughout the study period were the most likely to be in the top 10% of performers.
• Those in manual work had almost three times increased risk of poor cognition than those with an inactive job.

"Our analysis shows that the relationship between physical activity and cognitive is not straightforward," explained Hayat. "While regular physical activity has considerable benefits for protection against many chronic diseases, other factors may influence its effect on future poor cognition.

"People who have less active jobs - typically office-based, desk jobs - performed better at cognitive tests regardless of their education. This suggests that because desk jobs tend to be more mentally challenging than manual occupations, they may offer protection against cognitive decline."

It was not possible to say conclusively that physical activity in leisure time and desk-based work offer protection against cognitive decline. The researchers say that to answer this question, further studies will be required to include a more detailed exploration of the relationship of physical activity with cognition, particularly on inequalities across socio-economic groups and the impact of lower education.

###

The research was supported by the Medical Research Council, Cancer Research UK and the National Institute for Health Research.

Reference

Hayat, SA et al. Cross-sectional and prospective relationship between occupational and leisure time inactivity and cognitive function in an ageing population. The European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk) Study.

A chemical cocktail of air pollution in Beijing, China during COVID-19 outbreak

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

 

IMAGE: CHANGES IN PRIMARY AEROSOLS, GASEOUS PRECURSORS, AND SECONDARY AEROSOLS DURING THE COVID-19 OUTBREAK AND CHINESE NEW YEAR HOLIDAY. view more 

CREDIT: HAO LI

The novel coronavirus disease (COVID-19) spreads rapidly around the world, and has limited people's outdoor activities substantially. Air quality is therefore expected to be improved due to reduced anthropogenic emissions. However, in some megacities it has not been improved as expected and severe haze episodes still occurred during the COVID-19 lockdown.

A research team led by Prof. Yele Sun from the Institute of Atmospheric Physics of the Chinese Academy of Sciences analyzed six-year aerosol particle composition measurements to investigate responses of air quality to the changes in anthropogenic emissions during the COVID-19 outbreak in Beijing, China, as well as the Chinese New Year holiday effects on air pollution.

They found that air pollution during the COVID-19 lockdown was mainly due to different chemical responses of primary and secondary aerosols to changes in anthropogenic emissions.

"Primary gaseous and aerosol species responded directly to emission changes and decreased substantially by 30-50%", said Sun. "However, secondary aerosol species that are formed from oxidation of gaseous precursors and accounted for more than 70% of particulate matter remained small changes of less than 12%. Therefore, fine particle pollution hasn't been improved as expected."

The air quality in Beijing has been improved during the last decade, and the mass concentrations of both primary and secondary pollutants decreased considerably.

However, according to this new study published in Sci. Total Environ, the increased sulfur and nitrogen oxidation capacity have suppressed the effects of emission reductions due to enhanced secondary formation.

These findings highlight a great challenge for mitigating secondary air pollution in regions with a cocktail of high concentrations of gaseous precursors.

"There's an urgent need for a better understanding of the chemical interactions between precursors and secondary aerosol under complex meteorological environments," said Sun.

###

Remdesivir can save more lives where ICUs are overwhelmed: BU study

BOSTON UNIVERSITY SCHOOL OF MEDICINE

 

Amid news that the United States has bought up virtually the entire global supply of remdesivir, a new Boston University School of Public Health (BUSPH) study outlines how the drug could save lives in countries with less hospital capacity, such as South Africa, where COVID-19 is beginning to overwhelm intensive care units (ICUs).

Recent research has suggested that remdesivir can reduce deaths from COVID-19 by as much as 30%, but has a more significant effect on how long patients need intensive care, from an average of 15 days down to an average of 11 days.

The peer-reviewed study, published in the journal Clinical Infectious Diseases, estimates that remdesivir's ability to shorten ICU stays could increase the number of patients treated in South Africa's ICUs by more than 50%. This increased capacity could save as many as 6,862 lives per month as the country's cases peak. Add to that the potential lives saved directly from remdesivir treatment, and the drug could prevent the deaths of as many as 13,647 South Africans by December.

"There are many countries with limited ICU capacity that could benefit from this double impact on mortality," says study lead author Dr. Brooke Nichols, assistant professor of global health at BUSPH.

"Why would you use a drug--that has limited availability--to save one life when that same drug could be used to save two lives?"

Nichols says she is worried by the news that the U.S. has bought up the remdesivir supply, especially if the government doesn't even make sure that priority goes to overwhelmed U.S. locations.

"Because more lives can be saved per person treated when using remdesivir in places where ICU resources are breached, using remdesivir when ICU resources are not breached would be a misallocation of scarce resources," she says.

Nichols and study co-authors in Boston and South Africa have been modeling South Africa's COVID epidemic to help the country's government make informed decisions, and previously predicted that the country's ICU capacity could be overwhelmed as early as this month. The hardest-hit province, the Western Cape, exceeded ICU capacity in June.

For the remdesivir study, the researchers used their South African National COVID-19 Epidemiology model to look at the estimated three to six months when severe cases will exceed the country's 3,450 available ICU beds. If every one of South Africa's ICU patients with COVID received remdesivir, reducing the average ICU stay, the researchers estimated that the number of patients treated in ICUs from June to December would increase from between 23,443 and 32,284 patients to between 36,383 and 47,820.

The mortality rate for COVID-19 in ICUs varies from country to country and hospital to hospital, so the number of lives saved from increased ICU capacity would also vary. The researchers modeled several different scenarios, finding increased ICU capacity in South Africa could save 685 lives per month if a patient who needed intensive care was just as likely to die in an ICU than outside of one. At the other extreme, the researchers estimated that the increased ICU capacity from remdesivir could save as many as 6,682 lives per month if almost all patients who required but didn't receive ICU care died, but those who did receive ICU care had a 50-50 change of surviving.

If direct treatment with remdesivir also saved the lives of an additional 30 percent of patients--the current estimate for the drug--then the researchers estimated that remdesivir's "double impact" could save as many as 13,647 lives in South Africa by December.

###

About the Boston University School of Public Health

Founded in 1976, the Boston University School of Public Health is one of the top five ranked private schools of public health in the world. It offers master's- and doctoral-level education in public health. The faculty in six departments conduct policy-changing public health research around the world, with the mission of improving the health of populations--especially the disadvantaged, underserved, and vulnerable--locally and globally.

How to tackle climate change, food security and land degradation

Rutgers-led research highlights lesser-known options with fewer trade-offs

RUTGERS UNIVERSITY

 

IMAGE: A FARMER TENDS RICE FIELDS IN YEN BAI, VIETNAM, WHERE BALANCING GOALS FOR SUSTAINABLE DEVELOPMENT AND MANAGEMENT OF ECOSYSTEMS IS CHALLENGING. OPTIONS LIKE IMPROVED CROPLAND MANAGEMENT, INCREASING SOIL CARBON, AGROFORESTRY,... view more 

CREDIT: PAMELA MCELWEE/RUTGERS UNIVERSITY-NEW BRUNSWICK

How can some of world's biggest problems - climate change, food security and land degradation - be tackled simultaneously?

Some lesser-known options, such as integrated water management and increasing the organic content of soil, have fewer trade-offs than many well-known options, such as planting trees, according to a Rutgers-led study in the journal Global Change Biology.

"We argue that if we want to have an impact on multiple problems, we need to be smart about what options get us multiple benefits and which options come with potential trade-offs," said lead author Pamela McElwee, an associate professor in the Department of Human Ecology in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. "We found that many of the better-known solutions to climate mitigation and land degradation come with a lot of potentially significant trade-offs."

The idea of planting trees in vast areas to remove carbon dioxide from the air and reduce the impact of climate change, for example, has attracted a lot of attention, with some claiming it's the best "low-hanging fruit" approach to pursue, McElwee said. But large-scale tree planting could conflict directly with food security because both compete for available land. It could also diminish biodiversity, if fast-growing exotic trees replace native habitat.

Some potential options that don't get as much attention globally, but are quite promising with fewer trade-offs, include integrated water management, reducing post-harvest losses in agriculture, improving fire management, agroforestry (integrating trees and shrubs with croplands and pastures) and investing in disaster risk management, she said.

The study examined possible synergies and trade-offs with environmental and development goals. It was based on a massive literature review - essentially 1,400 individual literature reviews - conducted by scientists at many institutions. They compared 40 options to tackle the interrelated problems of climate change, food security and land degradation and looked for trade-offs or co-benefits with 18 categories of services provided by ecosystems, such as clean air and clean water, and the United Nations' 17 sustainable development goals. The work was done as part of an Intergovernmental Panel on Climate Change (IPCC) Special Report on Climate Change and Land released last year. Such reports offer only highlights, and this study includes all the details.

Several interventions show potentially significant negative impacts on sustainable development goals and ecosystem services. These include bioenergy (plant-based sources of energy such as wood fuels or ethanol) and bioenergy with carbon capture and storage, large-scale afforestation and some risk-sharing measures, such as commercial crop insurance.

The results show that a better understanding of the benefits and trade-offs of different policy approaches can help decision-makers choose the more effective - or at least the more benign - interventions.

"Policy officials can't always undertake the kind of work we did, so we hope our findings provide a useful shorthand for decision-makers," McElwee said. "We hope it helps them make the choices needed to improve future policy, such as strengthened pledges to tackle climate mitigation under the 2015 Paris Agreement. There are a lot of potential steps for reducing carbon emissions that aren't as well-known but should be on the table."

Soy and wheat proteins helpful for building aging muscles, but not as potent as animal protein

THE PHYSIOLOGICAL SOCIETY

 

IMAGE: THESE MEALS ARE EXAMPLES OF VEGETARIAN MEALS THAT HELP BUILD MUSCLE PROTEINS BECAUSE THEY CONSIST OF A COMPLEMENTARY AND COMPLETE PROFILE OF ALL ESSENTIAL AMINO ACIDS. view more 

CREDIT: PHOTO CREDIT: ANITA BEAN

On a gram for gram basis, animal proteins are more effective than plant proteins in supporting the maintenance of skeletal muscle mass with advancing age, shows research presented this week at The Physiological Society's virtual early career conference Future Physiology 2020.

The number of vegans in the UK has quadrupled since 2006, meaning that there are around 600,000 vegans in Great Britain (1). While we know plant-based diets are beneficial for the environment, we don't actually know how healthy these diets are for keeping muscles strong in elderly people.

Scientists generally agree that the primary driver of muscle loss with age -- at least in healthy individuals -- is a reduction of muscle proteins being built from amino acids. These amino acids come from protein that we eat and are also formed when we exercise.

Oliver Witard of King's College London is presenting research at The Physiological Society's Future Physiology 2020 conference about soy and wheat proteins showing that a larger dose of these plant proteins is required to achieve a comparable response of building muscles.

Simply transitioning from an animal-based protein diet to a plant-based diet, without adjusting total protein intake, will likely to be detrimental to muscle health during ageing. A more balanced and less extreme approach to changing dietary behaviour, meaning eating both animal and plant-based proteins, is best.

Witard and his colleagues conducted carefully controlled laboratory studies in human volunteers that involve the ingestion of plant compared with animal-based protein sources. To test changes in participants' muscles, they use several techniques including stable isotope methodology, blood sampling, and skeletal muscle biopsies to see how quickly the muscles were building up from amino acids.

It's important to note that this research to date has only compared two plant-based protein sources, namely soy and wheat. The researchers in this field will be conducting further research on other promising plant proteins such as oat, quinoa and maize.

Commenting on the research, Oliver Witard said: "This research challenges the broad viewpoint that plant proteins don't help build muscles as much as animal protein by highlighting the potential of alternative plant-based protein sources to maintain the size and quality of ageing muscles."

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Colleges that emphasize activism have more civically engaged students

BINGHAMTON UNIVERSITY

 

BINGHAMTON, NY -- Students tend to be more engaged in activism if the school that they attend emphasizes social and political issues, according to new research featuring faculty at Binghamton University, State University of New York.

A research team including Binghamton University Assistant Professor of Student Affairs Administration John Zilvinskis examined survey responses to an experimental itemset of the National Survey of Student Engagement measuring behaviors related to student activism. The sample included 3,257 seniors from 22 four-year institutions.

The survey items had respondents measure, "How much does your institution emphasize the following?"

- Discussing social or political issues, causes, campaigns or organizations
- Participating in activities focused on social or political issues, causes, campaigns or organizations
- Organizing activities focused on social or political issues, causes, campaigns or organizations
- Being an informed and active citizen focused on social or political issues, causes, campaigns or organizations

For administrators and educators in higher education, the researchers found that institutions with higher averages of emphasized activism had students who were more likely to participate in these behaviors.

"The higher institutional averages could indicate that a culture of emphasizing activism leads to more student engagement in activism; however, there also may be a self-selection effect in that activists choose to attend institutions that hold these values," said Zilvinskis.

The researchers also found that Black students and queer students were significantly more likely than other respondents to participate in activism.

"Our country has a history of marginalizing people from these groups, so I suspect they are more motivated to engage in activism behaviors to create more equitable experiences," said Zilvinskis. "The disappointing counter-finding is that their straight and White peers are not as engaged in activism."

Zilvinskis is now researching student participation in high-impact practices at community colleges and the engagement of students with disabilities at these institutions.

###

The paper, "Measuring Institutional Effects on Student Activism," was published in the Journal of College Student Development.

Flu in early life determines our susceptibility to future infections

New findings suggest early exposure to the flu affects how likely we are to acquire future infections and may also impact vaccine effectiveness

ELIFE

 

Early infections of influenza A can help predict how the virus will affect people across different ages in the future and could impact the effectiveness of flu vaccines, says a new study published today in eLife.

The findings may help improve estimates of both the age-specific risk of acquiring seasonal influenza infections and vaccine effectiveness in similarly vaccinated populations.

Seasonal influenza is an acute respiratory infection caused by influenza viruses that occur across the world. It causes approximately 100,000-600,000 hospitalisations and 5,000-27,000 deaths per year in the US alone. There are three types of seasonal influenza viruses in humans: A, B and C, although C is much less common. Influenza A viruses are further classified into subtypes, with the A(H1N1) and A(H3N2) subtypes currently circulating in humans. A(H1N1) is also written as A(H1N1)pdm09 as it caused the 2009 pandemic and replaced the A(H1N1) virus which had circulated before that year.*

The rapid evolution of seasonal influenza that allows it to escape preexisting immunity adds to the relatively high incidence of infections, including in previously infected older children and adults. But how susceptibility arises and changes over time in human populations has been difficult to quantify.

"Since the risk of influenza infection in a given age group changes over time, factors other than age may affect our susceptibility to infection," says first author Philip Arevalo, a postdoctoral researcher in senior author Sarah Cobey's lab, Department of Ecology and Evolution, University of Chicago, US. "We wanted to see whether these differences can be explained in part by the protection gained from childhood flu infection, which has lasting impacts on the immune response to future infections and the protection against new influenza A subtypes."

To measure the effect of early exposures to seasonal influenza on risk and vaccine effectiveness, Arevalo and his team applied statistical models to flu cases identified through seasonal studies of vaccine effectiveness from the 2007-2008 to 2017-2018 seasons in the Marshfield Epidemiologic Study Area (MESA) in Marshfield, Wisconsin, US. Each flu season, individuals in a defined community group were recruited and tested for flu when seeking outpatient care for acute respiratory infection. Those eligible for the study were individuals older than six months of age living in MESA and who received routine care from the Marshfield Clinic.

Despite the extensive evolution in influenza A subtypes H1N1 and H3N2 over the study period, the team's model showed that early infection reduces the risk of people needing to seek medical attention for infections with the same subtype later in life. This effect is stronger for H1N1 compared to H3N2. The model also revealed that the effectiveness of flu vaccines varies with both age and birth year, suggesting that this effectiveness also depends on early exposure.

"We hope the findings from our study will improve our understanding of influenza epidemiology and the low and variable effectiveness of the seasonal flu vaccine," concludes senior author Sarah Cobey, Principal Investigator at the Department of Ecology and Evolution, University of Chicago. "This would lead to better forecasting and vaccination strategies to help combat future flu seasons."

###

Reference

The paper 'Earliest infections predict the age distribution of seasonal influenza A cases', can be freely accessed online at https://doi.org/10.7554/eLife.50060. Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.

*Information provided by the World Health Organization at https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal).

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About eLife

eLife is a non-profit organisation created by funders and led by researchers. Our mission is to accelerate discovery by operating a platform for research communication that encourages and recognises the most responsible behaviours. We work across three major areas: publishing, technology and research culture. We aim to publish work of the highest standards and importance in all areas of biology and medicine, including Epidemiology and Global Health, and Microbiology and Infectious Disease, while exploring creative new ways to improve how research is assessed and published. We also invest in open-source technology innovation to modernise the infrastructure for science publishing and improve online tools for sharing, using and interacting with new results. eLife receives financial support and strategic guidance from the Howard Hughes Medical Institute, the Knut and Alice Wallenberg Foundation, the Max Planck Society and Wellcome. Learn more at https://elifesciences.org/about.

To read the latest Epidemiology and Global Health research published in eLife, visit https://elifesciences.org/subjects/epidemiology-global-health.

And for the latest in Microbiology and Infectious Disease, see https://elifesciences.org/subjects/microbiology-infectious-disease.

Study reveals many great lakes state parks impacted by record-high water levels

The research was presented at the 2020 Great Lakes Virtual Conference, which is hosted by the International Association of Great Lakes Research.

UNIVERSITY OF TOLEDO

 

IMAGE: GOLDEN HILL STATE PARK IN 2019 view more 

CREDIT: PATRICK LAWRENCE

Every summer millions of people visit parks and protected areas along the shorelines of the Great Lakes to camp, hike, swim and explore nature's beauty.

While COVID-19 has impacted staffing, operations and budgets at the parks, tourists this year also may notice changes if recent record-high water levels persist on Lake Huron, Lake Ontario, Lake Michigan, Lake Erie and Lake Superior.

A new study by a graduate student at The University of Toledo zeroes in on how coastal flooding and erosion in 2019 damaged park facilities and roads and interrupted visitor experiences, as well as examines the financial cost of the high water levels.

The research presented at the 2020 Great Lakes Virtual Conference, which is hosted by the International Association of Great Lakes Research, was completed by Eric Kostecky, a graduate student earning his master's degree in geography, as part of a course in environmental planning he took last fall while completing his undergraduate degree in geography and planning.

"A humbling statistic is that 75% of the parks indicated that continued higher lake levels in 2020 and beyond would further impact park operations and infrastructure," Kostecky said. "Future management actions would be to improve parking lots and roads and to move hiking trails, campgrounds and public access locations."

To gather information, Kostecky surveyed 50 parks along the Great Lakes, both federal and state parks in the United States and provincial parks in Canada. Twenty-nine responded.

"Even though Great Lakes parks and protected areas have experienced impacts from shoreline erosion and flooding during previous high water-level events in 1972-73 and 1985-86, this study is the first comprehensive attempt to catalogue those impacts," said Dr. Patrick Lawrence, professor and chair of the UToledo Department of Geography and Planning and Kostecky's faculty advisor.

The study shows 50% of the responding parks were impacted by both shoreline erosion and flooding, with the most common type of damage being to boat launches and building structures that were flooded, and roads near dunes washed away by waves.

Total cost of damage for 55% of the parks was $50,000 or less.

As a result of the damage, parks implemented a variety of changes for public safety last year: sections of the park were closed, select park operations were canceled, and some visitor education programs were suspended.

Great Lakes water levels peaked in July 2019, with increases varying between 14 and 31 inches above their long-term averages; Lake Superior was at 14 inches above its average, while Lake Michigan, Lake Huron, Lake Erie and Lake Ontario were at 31 inches above average, Lawrence said.

"The water levels in the Great Lakes fluctuate, but they don't fluctuate rapidly, so it's hard to say if we're still in the upswing or on the downswing," Kostecky said. "We won't know if we're continuing to rise or if waters have started to recede for the next couple of years."

The Great Lakes shoreline stretches 10,000 miles around eight U.S. states and Canada.

"Many parks and protected areas in the Great Lakes have struggled with the economic costs and interruptions of their operations, including services and programs for their visitors, and are concerned that as this period of high water levels continues this summer, they will face ongoing challenges in delivering the levels of public access and services to their visitors so eager to explore the parks and enjoy the nature and environment provided by these special spaces," Lawrence said.

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Tree rings show unprecedented rise in extreme weather in South America

Newly comprehensive continental drought atlas covers last 600 years

EARTH INSTITUTE AT COLUMBIA UNIVERSITY

 

IMAGE: ARAUCARIA ARAUCANA TREES IN NORTHERN PATAGONIA, ARGENTINA, SOME OF WHICH WERE USED IN THE STUDY. SOME TREES CAN LIVE 1,000 YEARS. view more 

CREDIT: RICARDO VILLALBA, ARGENTINE INSTITUTE OF SNOW, GLACIER AND ENVIRONMENTAL SCIENCES, AT THE NATIONAL RESEARCH COUNCIL FOR SCIENCE AND TECHNOLOGY

Scientists have filled a gaping hole in the world's climate records by reconstructing 600 years of soil-moisture swings across southern and central South America. Along with documenting the mechanisms behind natural changes, the new South American Drought Atlas reveals that unprecedented widespread, intense droughts and unusually wet periods have been on the rise since the mid-20th century. It suggests that the increased volatility could be due in part to global warming, along with earlier pollution of the atmosphere by ozone-depleting chemicals. The atlas was published this week in the journal Proceedings of the National Academy of Sciences.

Recent droughts have battered agriculture in wide areas of the continent, trends the study calls "alarming." Lead author Mariano Morales of the Argentine Institute of Snow, Glacier and Environmental Sciences at the National Research Council for Science and Technology, said, "Increasingly extreme hydroclimate events are consistent with the effects of human activities, but the atlas alone does not provide evidence of how much of the observed changes are due to natural climate variability versus human-induced warming." The new long-term record "highlights the acute vulnerability of South America to extreme climate events," he said.

Coauthor Edward Cook, head of the Tree Ring Lab at Columbia University's Lamont-Doherty Earth Observatory, said, "We don't want to jump off the cliff and say this is all climate change. There is a lot of natural variability that could mimic human-induced climate change." However, he said, armed with the new 600-year record, scientists are better equipped to sort things out.

The South American Drought Atlas is the latest in a series of drought atlases assembled by Cook and colleagues, covering many centuries of year-by-year climate conditions in North America; Asia; Europe and the Mediterranean; and New Zealand and eastern Australia. Subsequent studies building on the atlases have yielded new insights into how droughts may have adversely affected past civilizations, and the increasingly apparent role of human-induced warming on modern climate. Most recently, followup analyses of North America have suggested that warming is driving what may be the worst-ever known drought in the U.S. West.

The new atlas covers Argentina, Chile, Uruguay, Paraguay, most of Bolivia, and southern Brazil and Peru. It is the result of years of field collections of thousands of tree-ring records, and subsequent analyses by South American researchers, along with colleagues in Europe, Canada, Russia and the United States. Ring widths generally reflect yearly changes in soil moisture, and the researchers showed that collected rings correlate well with droughts and floods recorded starting in the early Spanish colonial period, as well as with modern instrumental measurements. This gave them confidence to extend the soil-moisture reconstruction back before written records.

The authors say that periodic natural shifts in precipitation are driven by complex, interlocking patterns of atmospheric circulation on land and at sea. One key factor: low-level westerly winds that blow moisture onto the continent from the Pacific. These are controlled in part by periodic cyclic changes in sea-surface temperatures over both the Pacific and the Atlantic, which can bring both droughts and wet periods. The authors say greenhouse-gas-driven shifts in these patterns appear linked to a still continuing 10-year drought over central Chile and western Argentina that has caused severe water shortages, along with heavier than normal rains in eastern regions.

Precipitation is also controlled in part by the Southern Annular Mode, a belt of westerly winds that circles Antarctica. This belt periodically contracts southward or expands northward, and when it contracts, it weakens the westerly winds that bring rain to South America. In recent decades, it has been stuck in the south -- largely a result of ozone-depleting chemicals used in 20th-century refrigerants that destroyed atmospheric ozone over Antarctica, scientists believe. The chemicals were banned in the 1980s, but their effects have persisted.

The third major factor is the so-called Hadley cell, a global phenomenon that lofts warm, moist air from near the equator and sends it further north and south, dropping precipitation as it goes. The air settles near the surface at predictable latitudes, by which time the moisture has been largely wrung out; this creates the permanently dry zones of the subtropics, including those in South America. During recent decades, the Hadley cell has expanded towards the poles, likely in response to human-induced climate changes; this has shifted rainfall patterns and broadened the subtropical dry zones, especially in the Southern Hemisphere.

The atlas indicates that there has been a steady increase in the frequency of widespread droughts since 1930, with the highest return times, about 10 years, occurring since the 1960s. Severe water shortages have affected central Chile and western Argentina from 1968-1969, 1976-1977, and 1996-1997. Currently, the drylands of central Chile and western Argentina are locked in one of the most severe decade-long droughts in the record. In some areas, up to two-thirds of some cereal and vegetable crops have been lost in some years. This threatens "the potential collapse of food systems," says Morales.

At the same time, southeastern parts of the continent are seeing heavier than normal rains. Walter Baethgen, who leads Latin American agricultural research for Columbia University's International Research Institute for Climate and Society, says his own studies show that the La Plata basin of Uruguay has seen more frequent extremely wet summers since 1970, with corresponding increases in crop and livestock production. But the frequency of very dry summers has remained the same, which translates to bigger losses of expected yields when they do come along, he said.

"Everything is consistent with the idea that you'll be intensifying both wet and dry events with global warming," said Jason Smerdon, a climate scientist at Lamont-Doherty and a coauthor of the study.

Using newly developed tree-ring records from Peru, Brazil, Bolivia and Colombia, the group is now working to expand the atlas to cover the entire continent, and extend the climate reconstruction back 1,000 years or more, said Morales.

The authors wish to dedicate the study to the memory of the late María del Rosario Prieto, their coauthor, and active promoter of environmental history studies in South America.

###

The paper, 'Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century,' can be obtained by contacting pnasnews@nas.edu or 202-334-1310

Scientist contacts:

Mariano Morales: mmorales@mendoza-conicet.gob.ar

Edward Cook: drdendro@ldeo.columbia.edu

Jason Smerdon: jsmerdon@ldeo.columbia.edu

More information: Kevin Krajick, Senior editor, science news, The Earth Institute

kkrajick@ei.columbia.edu 212-854-9729

Lamont-Doherty Earth Observatory is Columbia University's home for Earth science research. Its scientists develop fundamental knowledge about the origin, evolution and future of the natural world, from the planet's deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean, providing a rational basis for the difficult choices facing humanity. http://www.ldeo.columbia.edu | @LamontEarth

The Earth Institute, Columbia University mobilizes the sciences, education and public policy to achieve a sustainable earth. http://www.earth.columbia.edu.

Long-acting injectable form of HIV prevention outperforms daily pill in NIH study

Both methods highly effective at preventing HIV among men who have sex with men and transgender women

NIH/NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES

WHAT: A pre-exposure prophylaxis (PrEP) regimen containing an investigational long-acting form of the HIV drug cabotegravir injected once every 8 weeks was more effective than daily oral Truvada at preventing HIV acquisition among cisgender men who have sex with men and transgender women who have sex with men in a clinical trial sponsored by the National Institutes of Health. While both methods were highly effective for HIV prevention in the study population, the final data analysis indicated that cabotegravir had a superior protective effect. Findings from the Phase 2b/3 study, called HPTN 083, will be discussed in an online press conference and oral presentations during the 23rd International AIDS Conference (AIDS 2020: Virtual).

The only currently licensed PrEP medications--daily oral pills containing the HIV drugs tenofovir and emtricitabine--are highly effective at preventing HIV when taken as prescribed. However, taking a pill daily can be challenging. A long-acting form of PrEP could offer a less frequent, more discreet option that may be more desirable for some people. HPTN 083 and an ongoing companion study called HPTN 084, which is evaluating long-acting injectable cabotegravir for HIV prevention in cisgender women in sub-Saharan Africa, are sponsored by NIH's National Institute of Allergy and Infectious Diseases (NIAID).

In May 2020, a planned interim review of HPTN 083 data indicated a high level of efficacy for long-acting injectable cabotegravir among cisgender men and transgender women who have sex with men. The results reported today are based on a more extensive analysis of interim data from 4,566 study participants.

Overall, the rate of HIV acquisition in the participants was low. Among the 52 participants who acquired HIV, 13 were in the study group who received the cabotegravir-based PrEP regimen plus placebo daily oral tablets, and 39 were in the group who received daily oral Truvada plus placebo injections. This translated to an HIV incidence rate of 0.41% (95% confidence interval [CI] 0.22%-0.69%) in the cabotegravir group and 1.22% (95% CI 0.87%-1.67%) in the Truvada group--indicating 66% lower incidence in the cabotegravir group. Detailed analysis of these data indicated that the superior efficacy of cabotegravir was statistically significant.

Both products were safe and generally well-tolerated. Participants in the cabotegravir group were more likely to experience fever and pain or tenderness at the injection site compared to those in the Truvada group, who received placebo injections. Those in the Truvada group were more likely to report nausea. Most participants in the cabotegravir group received their injections as scheduled, with only 46 people (2.2%) discontinuing injections. Adherence to daily Truvada was also high, with 87% of a subset of 372 participants who provided blood samples having some detectable concentrations of the drug. Study investigators are continuing to follow the HPTN 083 study participants and to gather and analyze additional data on the long-term safety of injectable cabotegravir for HIV prevention.

NIAID collaborates on HPTN 083 with ViiV Healthcare, Gilead Sciences, Inc., and the NIH-funded HIV Prevention Trials Network (HPTN). NIAID and ViiV Healthcare co-fund the trial, which is conducted by the HPTN. ViiV Healthcare and Gilead Sciences, Inc., provide study medications. Three other NIH institutes also collaborate on HPTN 083: the National Institute of Mental Health, the National Institute on Drug Abuse, and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. More information about HPTN 083 is available on ClinicalTrials.gov under identifier NCT02720094.

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PRESENTATIONS: R. Landovitz et al. HPTN 083 interim results: pre-exposure prophylaxis containing long-acting injectable cabotegravir is safe and highly effective for cisgender men and transgender women who have sex with men. Oral presentation at the 23rd International AIDS Conference (AIDS 2020: Virtual), July 8, 5 p.m. ET

B. Grinsztejn et al. HPTN 083 interim results: efficacy of pre-exposure prophylaxis containing long-acting injectable cabotegravir is maintained across regions and key populations. Oral presentation at the 23rd International AIDS Conference (AIDS 2020: Virtual), July 9, 4 a.m. ET

WHO: Anthony S. Fauci, M.D., director of NIAID, and Carl W. Dieffenbach, Ph.D., director of NIAID's Division of AIDS, are available to comment.

CONTACT: To schedule interviews, please contact Hillary Hoffman, (301) 402-1663, niaidnews@niaid.nih.gov.

NIAID conducts and supports research--at NIH, throughout the United States, and worldwide--to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

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