Scientist Study

The triumph was hailed as a Wright brothers moment. The mini 4-pound (1.8-kilogram) copter even carried a bit of wing fabric from the Wright Flyer that made similar history at Kitty Hawk, North Carolina, in 1903.

It was a brief hop—just 39 seconds and 10 feet (3 meters)—but accomplished all the major milestones.

"We've been talking so long about our Wright brothers moment, and here it is," said project manager MiMi Aung, offering a virtual hug to her socially distanced colleagues in the control room as well as those at home because of the coronavirus pandemic.

Flight controllers at NASA's Jet Propulsion Laboratory in California declared success after receiving the data and images via the Perseverance rover. Ingenuity hitched a ride to Mars on Perseverance, clinging to the rover's belly when it touched down in an ancient river delta in February.

The $85 million helicopter demo was considered high risk, yet high reward.

Scientists cheered the news from around the world, even from space, and the White House offered its congratulations.

"A whole new way to explore the alien terrain in our solar system is now at our disposal," Nottingham Trent University astronomer Daniel Brown said from England.

This first test flight—with more to come by Ingenuity—holds great promise, Brown noted. Future helicopters could serve as otherworldly scouts for rovers, and eventually astronauts, in difficult, dangerous places.

Ground controllers had to wait more than three excruciating hours before learning whether the preprogrammed flight had succeeded 178 million miles (287 million kilometers) away. The first attempt had been delayed a week because of a software error.

When the news finally came, the operations center filled with applause, cheers and laughter. More followed when the first black and white photo from Ingenuity appeared, showing the helicopter's shadow as it hovered above the surface of Mars.

"The shadow of greatness, #MarsHelicopter first flight on another world complete!" NASA astronaut Victor Glover tweeted from the International Space Station.

The helicopter hovered for 30 seconds at its intended altitude of 10 feet (3 meters), and spent 39 seconds airborne, more than three times longer than the first successful flight of the Wright Flyer, which lasted a mere 12 seconds on Dec. 17, 1903.

To accomplish all this, the helicopter's twin, counter-rotating rotor blades needed to spin at 2,500 revolutions per minute—five times faster than on Earth. With an atmosphere just 1% the thickness of Earth's, engineers had to build a helicopter light enough—with blades spinning fast enough—to generate this otherworldy lift.

More than six years in the making, Ingenuity is just 19 inches (49 centimeters) tall, a spindly four-legged chopper. Its fuselage, containing all the batteries, heaters and sensors, is the size of a tissue box. The carbon-fiber, foam-filled rotors are the biggest pieces: Each pair stretches 4 feet (1.2 meters) tip to tip.

Ingenuity also had to be sturdy enough to withstand the Martian wind, and is topped with a solar panel for recharging the batteries, crucial for surviving the minus-130 degree Fahrenheit (minus-90 degree-Celsius) Martian nights.

NASA chose a flat, relatively rock-free patch for Ingenuity's airfield. Following Monday's success, NASA named the Martian airfield for the Wright brothers.

"While these two iconic moments in aviation history may be separated by time and ... million miles of space, they now will forever be linked," NASA's science missions chief Thomas Zurbuchen announced.

The little chopper with a giant job attracted attention from the moment it launched with Perseverance last July. Even Arnold Schwarzenegger joined in the fun, rooting for Ingenuity over the weekend. "Get to the chopper!" he shouted in a tweeted video, a line from his 1987 sci-fi film "Predator."

Up to five increasingly ambitious flights are planned, and they could lead the way to a fleet of Martian drones in decades to come, providing aerial views, transporting packages and serving as lookouts for human crews. On Earth, the technology could enable helicopters to reach new heights, doing things like more easily navigating the Himalayas.

Ingenuity's team has until the beginning of May to complete the test flights so that the rover can get on with its main mission: collecting rock samples that could hold evidence of past Martian life, for return to Earth a decade from now.

The team plans to test the helicopter's limits, possibly even wrecking the craft, leaving it to rest in place forever, having sent its data back home.

Until then, Perseverance will keep watch over Ingenuity. Flight engineers affectionately call them Percy and Ginny.

"Big sister's watching," said Malin Space Science Systems' Elsa Jensen, the rover's lead camera operator.

In recent years there has been an exhaustive study of red dwarf stars to find exoplanets in orbit around them. These stars have effective surface temperatures between 2400 and 3700 K (over 2000 degrees cooler than the Sun), and masses between 0.08 and 0.45 solar masses. In this context, a team of researchers led by Borja Toledo Padrón, a Severo Ochoa-La Caixa doctoral student at the Instituto de Astrofísica de Canarias (IAC), specializing in the search for planets around this type of stars, has discovered a super-Earth orbiting the star GJ 740, a red dwarf star situated some 36 light years from the Earth.

The planet orbits its star with a period of 2.4 days and its mass is around 3 times the mass of the Earth. Because the star is so close to the Sun, and the planet so close to the star, this new super-Earth could be the object of future researches with very large diameter telescopes towards the end of this decade. The results of the study were recently published in the journal Astronomy & Astrophysics.

“This is the planet with the second shortest orbital period around this type of star. The mass and the period suggest a rocky planet, with a radius of around 1.4 Earth radii, which could be confirmed in future observations with the TESS satellite”, explains Borja Toledo Padrón, the first author of the article. The data also indicate the presence of a second planet with an orbital period of 9 years, and a mass comparable to that of Saturn (close to 100 Earth masses), although its radial velocity signal could be due to the magnetic cycle of the star (similar to that of the Sun), so that more data are needed to confirm that the signal is really due to a planet.

The Kepler mission, recognised at one of the most successful in detecting exoplanets using the transit method (which is the search for small variations in the brightness of a star caused by the transit between it and ourselves of planets orbiting around it), has discovered a total of 156 new planets around cool stars. From its data it has been estimated that this type of stars harbours an average of 2.5 planets with orbital periods of less than 200 days. “The search for new exoplanets around cool stars is driven by the smaller difference between the planet’s mass and the star’s mass compared with stars in warmer spectral classes (which facilitates the detection of the planets’ signals), as well as the large number of this type of stars in our Galaxy”, comments Borja Toledo Padrón.

Cool stars are also an ideal target for the search for planets via the radial velocity method. This method is based on the detection of small variations in the velocity of a star due to the gravitational attraction of a planet in orbit around it, using spectroscopic observations. Since the discovery in 1998 of the first radial velocity signal of an exoplanet around a cool star, until now, a total of 116 exoplanets has been discovered around this class of stars using the radial velocity method. “The main difficulty of this method is related to the intense magnetic activity of this type of stars, which can produce spectroscopic signals very similar to those due to an exoplanet”, says Jonay I. González Hernández, an IAC researcher who is a co-author of this article.

The study is part of the project HADES (HArps-n red Dwarf Exoplanet Survey), in which the IAC is collaborating with the Institut de Ciències de l’Espai (IEEC-CSIC) of Catalonia, and the Italian programme GAPS (Global Architecture of Planetary Systems), whose objective is the detection and characterization of exoplanets round cool stars, in which are being used HARPS-N, on the Telescopio Nazionale Galileo (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma). This detection was possible due to a six year observing campaign with HARPS-N, complemented with measurements with the CARMENES spectrograph on the 3.5m telescope at the Calar Alto Observatory (Almería) and HARPS, on the 3.6m telescope at the La Silla Observatory (Chile), as well as photometric support from the ASAP and EXORAP surveys. Also participating in this work are IAC researchers Alejandro Suárez Mascareño, and Rafael Rebolo.

B. Toledo-Padrón, A. Suárez Mascareño, J. I. González Hernández, R. Rebolo, et al. “A super-Earth on a close-in orbit around the M1V star GJ 740”. Astronomy & Astrophysics, April 7th, 2021. DOI: 10.1051/0004-6361/202040099

One of the characteristic hallmarks of Alzheimer's disease (AD) is the buildup of amyloid-beta plaques in the brain. Most therapies designed to treat AD target these plaques, but they've largely failed in clinical trials. New research by Salk scientists upends conventional views of the origin of one prevalent type of plaque, indicating a reason why treatments have been unsuccessful.

The traditional view holds that the brain's trash-clearing immune cells, called microglia, inhibit the growth of plaques by "eating" them. The Salk scientists show instead that microglia promote the formation of dense-core plaques, and that this action sweeps wispy plaque material away from neurons, where it causes cell death. The research, which was published in Nature Immunology on April 15, 2021, suggests that dense-core plaques play a protective role, so treatments to destroy them may do more harm than good.

"We show that dense-core plaques don't form spontaneously. We believe they're built by microglia as a defense mechanism, so they may be best left alone," says Greg Lemke, a professor in Salk's Molecular Neurobiology Laboratory. "There are various efforts to get the FDA to approve antibodies whose main clinical effect is reducing dense-core plaque formation, but we make the argument that breaking up the plaque may be doing more damage."

Alzheimer's disease is a neurological condition that results in memory loss, impairment of thinking, and behavioral changes, which worsen as we age. The disease seems to be caused by abnormal proteins aggregating between brain cells to form the hallmark plaques, which interrupt activity that keeps the cells alive.

There are numerous forms of plaque, but the two most prevalent are characterized as "diffuse" and "dense-core." Diffuse plaques are loosely organized, amorphous clouds. Dense-core plaques have a compact center surrounded by a halo. Scientists have generally believed that both types of plaque form spontaneously from excess production of a precursor molecule called amyloid precursor protein (APP).

But, according to the new study, it is actually microglia that form dense-core plaques from diffuse amyloid-beta fibrils, as part of their cellular cleanup.

This builds on a 2016 discovery by the Lemke lab, which determined that when a brain cell dies, a fatty molecule flips from the inside to the outside of the cell, signaling, "I'm dead, eat me." Microglia, via surface proteins called TAM receptors, then engulf, or "eat" the dead cell, with the help of an intermediary molecule called Gas6. Without TAM receptors and Gas6, microglia cannot connect to dead cells and consume them.

The team's current work shows that it's not only dead cells that exhibit the eat-me signal and Gas6: So do the amyloid plaques prevalent in Alzheimer's disease. Using animal models, the researchers were able to demonstrate experimentally for the first time that microglia with TAM receptors eat amyloid plaques via the eat-me signal and Gas6. In mice engineered to lack TAM receptors, the microglia were unable to perform this function.

Digging deeper, they traced the dense-core plaques using live imaging. Much to their surprise, the team discovered that after a microglial cell eats a diffuse plaque, it transfers the engulfed amyloid-beta to a highly acidic compartment and converts it into a highly compacted aggregate that is then transferred to a dense-core plaque. The researchers propose that this is a beneficial mechanism, organizing diffuse into dense-core plaque and clearing the intercellular environment of debris.

"Our research seems to show that when there are fewer dense-core plaques, there seem to be more detrimental effects," says Youtong Huang, first author on the paper. "With more-diffuse plaques, there's an abundance of dystrophic neurites, a proxy for neuronal damage. I don't think there's a distinct clinical decision on which form of plaque is more or less detrimental, but through our research, we seem to find that dense-core plaques are a bit more benign."

Their findings suggest new ways of developing a treatment for Alzheimer's disease, such as boosting expression of TAM receptors on microglia to accelerate dense-core plaque formation. The team would like to conduct cognitive studies to see if increasing the activity of microglial TAM receptors would alleviate the effects of AD.

Lemke, who holds the Françoise Gilot-Salk Chair, believes that the current failure rate of most Alzheimer's drug trials is about to end. "Some people are saying that the relative failure of trials that bust up dense-core plaques refutes the idea that amyloid-beta is a bad thing in the brain," says Lemke. "But we argue that amyloid-beta is still clearly a bad thing; it's just that you've got to ask whether dense-core plaques are a bad thing."

Lemke suggests that scientists looking for a cure for Alzheimer's should stop trying to focus on breaking up dense-core plaques and start looking at treatments that either reduce the production of amyloid-beta in the first place or therapies that facilitate transport of amyloid-beta out of the brain altogether.

Huang Y, Happonen KE, Burrola PG, et al. Microglia use TAM receptors to detect and engulf amyloid β plaques. Nat Immunol. 2021:1-9. doi: 10.1038/s41590-021-00913-5

Scientists at Sanford Burnham Prebys have identified a set of human genes that fight SARS-CoV-2 infection, the virus that causes COVID-19. Knowing which genes help control viral infection can greatly assist researchers' understanding of factors that affect disease severity and also suggest possible therapeutic options. The genes in question are related to interferons, the body's frontline virus fighters.

The study was published in the journal Molecular Cell.

"We wanted to gain a better understanding of the cellular response to SARS-CoV-2, including what drives a strong or weak response to infection," says Sumit K. Chanda, Ph.D., professor and director of the Immunity and Pathogenesis Program at Sanford Burnham Prebys and lead author of the study. "We've gained new insights into how the virus exploits the human cells it invades, but we are still searching for its Achille's heel so that we can develop optimal antivirals."

Soon after the start of the pandemic, clinicians found that a weak interferon response to SARS-CoV-2 infection resulted in some of the more severe cases of COVID-19. This knowledge led Chanda and his collaborators to search for the human genes that are triggered by interferons, known as interferon-stimulated genes (ISGs), which act to limit SARS-CoV-2 infection.

Based on knowledge gleaned from SARS-CoV-1, the virus that caused a deadly, but relatively brief, outbreak of disease from 2002 to 2004, and knowing that it was similar to SARS-CoV-2, the investigators were able to develop laboratory experiments to identify the ISGs that control viral replication in COVID-19.

"We found that 65 ISGs controlled SARS-CoV-2 infection, including some that inhibited the virus' ability to enter cells, some that suppressed manufacture of the RNA that is the virus's lifeblood, and a cluster of genes that inhibited assembly of the virus," says Chanda. "What was also of great interest was the fact that some of the ISGs exhibited control across unrelated viruses, such as seasonal flu, West Nile and HIV, which leads to AIDS". 

"We identified eight ISGs that inhibited both SARS-CoV-1 and CoV-2 replication in the subcellular compartment responsible for protein packaging, suggesting this vulnerable site could be exploited to clear viral infection," says Laura Martin-Sancho, Ph.D., a senior postdoctoral associate in the Chanda lab and first author of this study. "This is important information, but we still need to learn more about the biology of the virus and investigate if genetic variability within these ISGs correlates with COVID-19 severity."

As a next step, the researchers will look at the biology of SARS-CoV-2 variants that continue to evolve and threaten vaccine efficacy. Martin-Sancho notes that they have already started gathering variants for laboratory investigation,

"It's vitally important that we don't take our foot off the pedal of basic research efforts now that vaccines are helping control the pandemic," concludes Chanda. "We've come so far so fast because of investment in fundamental research at Sanford Burnham Prebys and elsewhere, and our continued efforts will be especially important when, not if, another viral outbreak occurs."

Even though researchers are working on it now, but the truth is the first step was taken in the last decade. At that time, two quantum devices were connected via a physical link.

To create a scalable quantum network, it is essential to pass quantum information through intermediate nodes. Also, several applications rely on entangled quantum bits distributed between multiple nodes.

Quantum entanglement offers quantum computers enormous power, and it is the fundamental resource for sharing quantum information over the future quantum internet.

By realizing their quantum network in the lab, a team of researchers at QuTech—a collaboration between Delft University of Technology and TNO—is the first to have connected two quantum processors through an intermediate node and established shared entanglement between multiple stand-alone quantum processors.

Usually, the quantum network consists of three quantum nodes at some distance within the same building. To prepare these nodes to operate, scientists invented a novel architecture that enables scaling beyond a single link.

The middle node (called Bob) has a physical connection to both outer nodes (called Alice and Charlie), allowing entanglement links with each of these nodes to be established. Bob is equipped with an additional quantum bit that can be used as memory, allowing a previously generated quantum link to be stored while a new link is being established. After establishing the quantum links Alice-Bob and Bob-Charlie, a set of quantum operations at Bob converts these links into a quantum link Alice-Charlie. Alternatively, by performing a different set of quantum operations at Bob, entanglement between all three nodes is established.

An exciting feature of this quantum network is that it announces the successful completion of these (intrinsically probabilistic) protocols with a “flag” signal. Such heralding is crucial for scalability, as, in a future quantum internet, many of such protocols will need to be concatenated.

Sophie Hermans, another member of the team, said, “Once established, we could preserve the resulting entangled states, protecting them from noise. It means that, in principle, we can use these states for quantum key distribution, a quantum computation, or any other subsequent quantum protocol.”

This newly established first entanglement-based quantum network offers scientists a unique testbed for developing and testing quantum internet hardware, software, and protocols.

Ronald Hanson, who led the research team, said, “Colleagues at QuTech are already looking into future compatibility with existing data infrastructures. In due time, the current proof-of-principle approach will be tested outside the lab on existing telecom fiber—on QuTech’s Quantum internet Demonstrator, of which the first metropolitan link is scheduled to be completed in 2022.”

In the future, scientists are looking forward to adding more quantum bits to their three-node network and on adding higher-level software and hardware layers.

Pompili said, “Once all the high-level control and interface layers for running the network have been developed, anybody will be able to write and run a network application without needing to understand how lasers and cryostats work. That is the end goal.”

“Realization of a multinode quantum network of remote solid-state qubits” Science (2021). DOI: 10.1126/science.abg1919

Sugar practically screams from the shelves of your grocery store, especially those products marketed to kids.

Children are the highest consumers of added sugar, even as high-sugar diets have been linked to health effects like obesity and heart disease and even impaired memory function.

However, less is known about how high sugar consumption during childhood affects the development of the brain, specifically a region known to be critically important for learning and memory called the hippocampus.

New research led by a University of Georgia faculty member in collaboration with a University of Southern California research group has shown in a rodent model that daily consumption of sugar-sweetened beverages during adolescence impairs performance on a learning and memory task during adulthood. The group further showed that changes in the bacteria in the gut may be the key to the sugar-induced memory impairment.

Supporting this possibility, they found that similar memory deficits were observed even when the bacteria, called Parabacteroides, were experimentally enriched in the guts of animals that had never consumed sugar.

“Early life sugar increased Parabacteroides levels, and the higher the levels of Parabacteroides, the worse the animals did in the task,” said Emily Noble, assistant professor in the UGA College of Family and Consumer Sciences who served as first author on the paper. “We found that the bacteria alone was sufficient to impair memory in the same way as sugar, but it also impaired other types of memory functions as well.”

The Dietary Guidelines for Americans, a joint publication of the U.S. Departments of Agriculture and of Health and Human Services, recommends limiting added sugars to less than 10 percent of calories per day.

Data from the Centers for Disease Control and Prevention show Americans between the ages 9-18 exceed that recommendation, the bulk of the calories coming from sugar-sweetened beverages.

Considering the role the hippocampus plays in a variety of cognitive functions and the fact the area is still developing into late adolescence, researchers sought to understand more about its vulnerability to a high-sugar diet via gut microbiota.

Juvenile rats were given their normal chow and an 11% sugar solution, which is comparable to commercially available sugar-sweetened beverages.

Researchers then had the rats perform a hippocampus-dependent memory task designed to measure episodic contextual memory, or remembering the context where they had seen a familiar object before.

“We found that rats that consumed sugar in early life had an impaired capacity to discriminate that an object was novel to a specific context, a task the rats that were not given sugar were able to do,” Noble said.

A second memory task measured basic recognition memory, a hippocampal-independent memory function that involves the animals’ ability to recognize something they had seen previously.

In this task, sugar had no effect on the animals’ recognition memory.

“Early life sugar consumption seems to selectively impair their hippocampal learning and memory,” Noble said.

Additional analyses determined that high sugar consumption led to elevated levels of Parabacteroides in the gut microbiome, the more than 100 trillion microorganisms in the gastrointestinal tract that play a role in human health and disease.

To better identify the mechanism by which the bacteria impacted memory and learning, researchers experimentally increased levels of Parabacteroides in the microbiome of rats that had never consumed sugar. Those animals showed impairments in both hippocampal dependent and hippocampal-independent memory tasks.

“(The bacteria) induced some cognitive deficits on its own,” Noble said.

Noble said future research is needed to better identify specific pathways by which this gut-brain signaling operates.

“The question now is how do these populations of bacteria in the gut alter the development of the brain?” Noble said. “Identifying how the bacteria in the gut are impacting brain development will tell us about what sort of internal environment the brain needs in order to grow in a healthy way.”

Emily E. Noble, Christine A. Olson, Elizabeth Davis, Linda Tsan, Yen-Wei Chen, Ruth Schade, Clarissa Liu, Andrea Suarez, Roshonda B. Jones, Claire de La Serre, Xia Yang, Elaine Y. Hsiao, Scott E. Kanoski. Gut microbial taxa elevated by dietary sugar disrupt memory function. Translational Psychiatry, 2021; 11 (1) DOI: 10.1038/s41398-021-01309-7

"As we are unable to conduct certain types of experiments in humans, it is essential that we have better models to more accurately study and understand human biology and disease," says senior author Juan Carlos Izpisua Belmonte, a professor in the Gene Expression Laboratory at the Salk Institute for Biological Sciences. "An important goal of experimental biology is the development of model systems that allow for the study of human diseases under in vivo conditions."

Interspecies chimeras in mammals have been made since the 1970s, when they were generated in rodents and used to study early developmental processes. The advance that made the current study possible came last year when this study's collaborating team—led by Weizhi Ji of Kunming University of Science and Technology in Yunnan, China—generated technology that allowed monkey embryos to stay alive and grow outside the body for an extended period of time.

In the current study, six days after the monkey embryos had been created, each one was injected with 25 human cells. The cells were from an induced pluripotent cell line known as extended pluripotent stem cells, which have the potential to contribute to both embryonic and extra-embryonic tissues. After one day, human cells were detected in 132 embryos. After 10 days, 103 of the chimeric embryos were still developing. Survival soon began declining, and by day 19, only three chimeras were still alive. Importantly, though, the percentage of human cells in the embryos remained high throughout the time they continued to grow.

"Historically, the generation of human-animal chimeras has suffered from low efficiency and integration of human cells into the host species," Izpisua Belmonte says. "Generation of a chimera between human and non-human primate, a species more closely related to humans along the evolutionary timeline than all previously used species, will allow us to gain better insight into whether there are evolutionarily imposed barriers to chimera generation and if there are any means by which we can overcome them."

The investigators performed transcriptome analysis on both the human and monkey cells from the embryos. "From these analyses, several communication pathways that were either novel or strengthened in the chimeric cells were identified," Izpisua Belmonte explains. "Understanding which pathways are involved in chimeric cell communication will allow us to possibly enhance this communication and increase the efficiency of chimerism in a host species that's more evolutionarily distant to humans."

An important next step for this research is to evaluate in more detail all the molecular pathways that are involved in this interspecies communication, with the immediate goal of finding which pathways are vital to the developmental process. Longer term, the researchers hope to use the chimeras not only to study early human development and to model disease, but to develop new approaches for drug screening, as well as potentially generating transplantable cells, tissues, or organs.

An accompanying Preview in Cell outlines potential ethical considerations surrounding the generation of human/non-human primate chimeras. Izpisua Belmonte also notes that "it is our responsibility as scientists to conduct our research thoughtfully, following all the ethical, legal, and social guidelines in place." He adds that before beginning this work, "ethical consultations and reviews were performed both at the institutional level and via outreach to non-affiliated bioethicists. This thorough and detailed process helped guide our experiments."

Current guidelines indicate that adults should have a minimum of two-and-a-half hours of moderate intensity exercise each week, but a new study led by UCSF Benioff Children's Hospitals reveals that boosting exercise to as much as five hours a week may protect against hypertension in midlife—particularly if it is sustained in one's thirties, forties and fifties.

In the study publishing in American Journal of Preventive Medicine on April 15, researchers followed approximately 5,000 adults ages 18 to 30 for 30 years. The participants were asked about their exercise habits, medical history, smoking status and alcohol use. Blood pressure and weight were monitored, together with cholesterol and triglycerides.

Hypertension was noted if blood pressure was 130 over 80 mmHg, the threshold established in 2017 by the American College of Cardiology/American Heart Association.

The 5,115 participants had been enrolled by the Coronary Artery Risk Development in Young Adults (CARDIA) study and came from urban sites in Birmingham, Ala., Chicago, Minneapolis and Oakland, Calif. Approximately half the participants were Black (51.6 percent) and the remainder were White. Just under half (45.5 percent) were men.

Among the four groups, who were categorized by race and gender, Black men were found to be the most active in early adulthood, exercising slightly more than White men and significantly more than Black women and White women. But by the time Black men reached age 60, exercise intake had slumped from a peak of approximately 560 exercise units to around 300 units, the equivalent to the minimum of two-and-a-half hours a week of moderate intensity exercise recommended by the U.S. Department of Health and Human Services. This was substantially less exercise than White men (approximately 430 units) and slightly more than White women (approximately 320 units). Of the four groups, Black women had the least exercise throughout the study period and saw declines over time to approximately 200 units.

"Although Black male youth may have high engagement in sports, socio-economic factors, neighborhood environments, and work or family responsibilities may prevent continued engagement in physical activity through adulthood," said first author Jason Nagata, MD, of the UCSF Division of Adolescent and Young Adult Medicine. Additionally, Black men reported the highest rates of smoking, which may preclude physical activity over time, he noted.

Physical activity for White men declined in their twenties and thirties and stabilized at around age 40. For White women, physical activity hovered around 380 exercise units, dipping in their thirties and remaining constant to age 60.

Rates of hypertension mirrored this declining physical activity. Approximately 80-to-90 percent of Black men and women had hypertension by age 60, compared with just below 70 percent for White men and 50 percent for White women.

"Results from randomized controlled trials and observational studies have shown that exercise lowers blood pressure, suggesting that it may be important to focus on exercise as a way to lower blood pressure in all adults as they approach middle age," said senior author Kirsten Bibbins-Domingo, MD, Ph.D., of the UCSF Department of Epidemiology and Biostatistics.

"Teenagers and those in their early twenties may be physically active but these patterns change with age. Our study suggests that maintaining physical activity during young adulthood—at higher levels than previously recommended—may be particularly important."

When researchers looked at the 17.9 percent of participants who had moderate exercise for at least five hours a week during early adulthood—double the recommended minimum—they found that the likelihood of developing hypertension was 18 percent lower than for those who exercised less than five hours a week. The likelihood was even lower for the 11.7 percent of participants who maintained their exercise habits until age 60.

Patients should be asked about physical activity in the same way as they are routinely checked for blood pressure, glucose and lipid profiles, obesity and smoking, Nagata said, and intervention programs should be held at schools, colleges, churches, workplaces and community organizations. Black women have high rates of obesity and smoking, and low rates of physical activity, he said, and should be an important group for targeted intervention.

"Nearly half of our participants in young adulthood had suboptimal levels of physical activity, which was significantly associated with the onset of hypertension, indicating that we need to raise the minimum standard for physical activity," Nagata said. "This might be especially the case after high school when opportunities for physical activity diminish as young adults transition to college, the workforce and parenthood, and leisure time is eroded."