Sunday, November 30, 2014

Probably good news for many who are hoping to find a way to lower prices at the gas pump, but equally important, this new study utilizing waste matter to create fuel demonstrates the need to address the consequences of an over crowded Earth. We cannot continue to ignore that with abundance comes health issues related to excessivity.

From Medical News Today - 

Scientists develop process that turns human waste into rocket fuel

Last updated: 

During a spaceflight, any human waste generated by astronauts is stored in containers and loaded into capsules that burn up as they pass through the Earth's atmosphere. But in a new study - published in the journalAdvances in Space Research - researchers from the University of Florida say they have found a way to put this waste to use; they can convert it into a biogas that fuels rockets.
A space shuttle
Researchers say they have found a way to turn human waste into a biogas that can power space shuttles.
For short spaceflights, the unloading and burning up of human waste is not too much of a problem. But it is when it comes to long-term missions, such as NASA's plan to set up an inhabitable unit on the moon for 5 years from 2019.
Of course, the human waste generated during that time cannot be left on the moon, but bringing it back to Earth would significantly increase the weight of the shuttle. NASA approached University of Florida researchers Abhishek Dhoble and Pratap Pullammanappallil to come up with a solution.
To kick start the team's research, NASA provided them with packages of human waste that had been chemically produced, alongside packages of food waste, towels, wash cloths, clothing and other waste that would likely be generated by astronauts living on the moon for 5 years.
Dhoble and Pullammanappallil set out to see how much methane they could generate from such waste. Space shuttles are usually powered by liquid hydrogen and liquid oxygen, but in recent years, scientists have looked to methane as a source of rocket fuel.
"Methane can be used to fuel the rockets," says Pullammanappallil. "The idea [behind this research] was to see whether we could make enough fuel to launch rockets and not carry all the fuel and its weight from Earth for the return journey."

'Enough methane can be produced to come back from the moon'

The team developed an anaerobic digester process. This process destroys pathogens in human waste before breaking down organic matter and producing a combination of methane and carbon dioxide.
Using this process, the team found they could produce 290 liters of methane for each crew member every day over 1 week. "Enough methane can be produced to come back from the moon," says Pullammanappallil.
The process could also provide astronauts with a back-up oxygen system. The team says it has potential to produce around 200 gallons of non-drinkable water a year. This water is present in the organic matter of human waste and is released as it decomposes. The water can be divided into hydrogen and oxygen through electrolysis, and the astronauts would be able to inhale the oxygen.
What is more, the newly created technique may also be useful here on Earth. The researchers say the fuel it produces could be used to generate electricity and heating. "It could be used on campus or around town, or anywhere, to convert waste into fuel," adds Pullammanappallil.
Human waste may have other benefits, too. Medical News Today recently reported on a study claimingClostridium difficile infection could be treated with frozen encapsulated fecal matter.
Written by 

Monday, November 24, 2014

The epidemic of Metabolic Syndrome (large waist, high triglycerides, low HDL, high blood sugar), a leading precursor to diabetes and heart disease, may be prevented according to a new study. A healthy level of gut bacteria brought about by a change in diet - and perhaps the using of a quality probiotic supplement - can make the difference.

 From Medical News Today -

Metabolic syndrome may be prevented by healthy gut bacteria

Last updated:


Healthy bacteria that live in the intestine may help treat or prevent metabolic syndrome, according to a new study published in the journal Gastroenterology
 
 

illustration of bacteria
As well as promoting the inflammation that leads to metabolic syndrome, altered gut microbiota promotes chronic inflammatory diseases such as Crohn's disease.
Metabolic syndrome is a combination of risk factors that increase risk for heart disease, diabetes and stroke. When a person has three of the following risk factors, they have metabolic syndrome:
  • A large waistline
  • High levels of triglyceride (a type of fat found in the blood)
  • Low high-density lipoprotein (HDL) cholesterol level
  • High fasting blood sugar.
People with metabolic syndrome are twice as likely to develop heart disease and five times as likely to develop diabetes as the general population, according to the National Institutes of Health.

The American Heart Association report that about 34% of American adults have metabolic syndrome, and it is becoming more common, prompting scientists to investigate possible causes.
The team behind the new study - from Georgia State University (Atlanta) and Cornell University (Ithaca, NY) - had found in previous research that altered gut microbiota (intestinal bacteria) plays a role in metabolic syndrome.

As well as promoting the inflammation that leads to metabolic syndrome, altered gut microbiota promotes chronic inflammatory diseases such as Crohn's disease and ulcerative colitis.

New study explains mechanisms identified in previous research


According to Dr. Andrew Gewirtz, a professor in the Institute for Biomedical Sciences at Georgia State, the new study has filled in the details about how these mechanisms work.

"It's the loss of TLR5 on the epithelium," he explains, "the cells that line the surface of the intestine and their ability to quickly respond to bacteria. That ability goes away and results in a more aggressive bacterial population that gets closer in and produces substances that drive inflammation." 
 
In a model of mouse siblings, the researchers demonstrated that the altered gut microbiota that promotes inflammation is more aggressive than other bacteria in infiltrating the epithelium.

Some of the mice in the study were missing the TLR5 gene, which the researchers found caused alterations in the inflammation-driving bacteria that promoted metabolic syndrome.

Dr. Ruth Ley, of the departments of Microbiology and Molecular Biology at Cornell, explains the findings:
"These results suggest that developing a means to promote a more healthy microbiota can treat or prevent metabolic disease.
They confirm the concept that altered microbiota can promote low-grade inflammation and metabolic syndrome and advance the underlying mechanism. We showed that the altered bacterial population is more aggressive in infiltrating the host and producing substances, namely flagellin and lipopolysaccharide, that further promote inflammation."
Recently, Medical News Today reported on research that a Mediterranean diet with nuts and olive oil may "reverse" metabolic syndrome.

In that study, participants followed either a low-fat diet, a Mediterranean diet supplemented with nuts or a Mediterranean diet supplemented with extra-virgin olive oil, and they were followed for an average of 4.8 years.

The participants who followed the Mediterranean diets experienced a reduction in blood glucose levels and abdominal obesity. At the start of the study, 64% of participants had metabolic syndrome. However, by the end of the study, 28.2% of the participants following Mediterranean diets no longer met the diagnostic criteria for metabolic syndrome.

Other associated health benefits of the Mediterranean diet are investigated in our Knowledge Center article.

Written by

Tuesday, November 18, 2014

If you're trying to get in shape, lose weight, and improve your cardiovascular system but are afraid that should you start running your knees will get arthritic...don't worry about it. Yet another study demonstrates that risk of OA in joggers is lower than in those who lead a sedentary lifestyle. So put down the remote, get off the couch, and go discover the benefits of getting fit regardless of your age!

Medpage Today

Knee OA Risk Lower in Joggers

Published: Nov 17, 2014 | Updated: Nov 17, 2014



BOSTON -- People who run at any time of life have lower rates of knee pain and osteoarthritis (OA) compared with nonrunners, according to cross-sectional analysis of data from the Osteoarthritis Initiative (OAI).

"Based on our findings, clinicians can say to those who don't already have osteoarthritis, that running does not appear harmful to the knee from the perspective of developing radiographic evidence of knee OA and knee pain. These people should not be discouraged from running," lead investigator Grace Hsiao-Wei Lo, MD from Baylor College of Medicine in Houston, told MedPage Today.

"I was mostly trying to show that running wasn't harmful to the knee. It was a nice surprise to find that it might actually have positive benefits for the knee," she added.

The study included 2,683 subjects, mean age 64.5 years, with a mean body mass index (BMI) of 28 kg/m2.

All participants had knee radiograph readings, and knee pain was assessed by questionnaire.
Roughly 29% (n=776) of the subjects reported that they had run at some time in their lives.

"We asked specifically for people to think back over their lives between the ages of 12 to 18, 19 to 34, 35 to 49, and then greater than or equal to 50," explained Dr. Lo during a press conference at the annual meeting of the American College of Rheumatology.

"During each of those age ranges we asked people to indicate the top three activities that they participated in [more than 20 times in life]. If they indicated running as one of those activities we indicated them as a runner for that particular time frame."

The researchers looked at the relationship between running over a lifetime and knee pain, radiographic osteoarthritis (ROA) of the knee, and symptomatic ROA of the knee, "meaning that people had to have both pain and evidence of radiographic OA on the same knee," she said.

They found that people who ran at any time of life had a lower prevalence of both frequent knee pain and symptomatic ROA compared with nonrunners (35.0% versus 41.6%, odds ratio 0.87; and 22.8% versus 29.8%; OR 0.83, respectively) -- differences that remained statistically significant after adjusting for age, sex, and BMI, she said.

There is controversy regarding whether habitual running is beneficial or harmful to the knee because chronic, mechanical overloading could potentially physically damage structures within the knee, said Dr. Lo. "But, alternatively, runners have a lower BMI which we know is protective of knee OA."

The question of whether or not running increases the risk of OA is particularly relevant because the physical activity guidelines from the Centers for Disease Control recommend 75 minutes per week of vigorous aerobic activity such as running, she said.

Most previous studies looking at the relationship of running and knee OA have focused on elite male runners and are therefore not generalizable, she noted.

"There's really little data out there addressing this question in the general population and so Dr. Lo's study is, I think, one of the first to look at this question in a population-based study," said moderator Rob McLean, DSc, MPH, an epidemiologist at Harvard Medical School in Boston.

Thursday, November 13, 2014

Simple: Burn more calories with exercise than the amount of calories you eat equals weight loss. Or so one would think. A new study out of Arizona State University says many people who exercise actually gain weight from increased body fat! Well, is it a question of people eating more because they are exercising? A NY Times story reports it may just be the case.


Exercising but Gaining Weight



Exercise has innumerable health benefits, but losing weight may not be among them. A provocative new study shows that a substantial number of people who take up an exercise regimen wind up heavier afterward than they were at the start, with the weight gain due mostly to extra fat, not muscle.

But the study also finds, for the first time, that one simple strategy may improve people’s odds of actually dropping pounds with exercise.

As we all know, the fundamentals of weight loss should be simple. Burn more calories on any given day than you consume and, over time, you will lose weight. Theoretically, we can achieve that desirable condition by reducing the number of calories that we take in through dieting or by increasing the number of calories that we incinerate through exercise.

But in reality, most people do not achieve or sustain weight loss, no matter what method they try.
Exercise is particularly problematic in this regard. A recent review of studies related to exercise and weight control found that in most of the studies, people lost barely a third as many pounds as would have been expected, given how many calories they were burning during workouts. Many studies also report enormous variations in how people’s waistlines respond to the same exercise program, with some people dropping pounds and others gaining fat.

Scientists have had little understanding, however, of why exercise helps some people but not others to shed pounds or whether there might be early indications of how people will respond to an exercise routine.

So for the new study, which was published last month in The Journal of Strength and Conditioning Research, scientists at Arizona State University in Phoenix recruited 81 healthy but sedentary adult women. All of the women were overweight, based on their body mass index, but some were significantly heavier than others. None had exercised regularly in the past year.

The women were told that they would be joining a fitness study and would exercise in order to improve their aerobic endurance. The scientists asked the women not to change their eating habits in any way.

Each of the volunteers visited the physiology lab at the start of the study and the scientists determined their weight, B.M.I., percentage of body fat, current endurance level, and others measures of health and fitness.

Then each woman began a supervised exercise program designed to be vigorous but manageable by most people, said Glenn Gaesser, a professor of nutrition and health promotion at Arizona State and senior author of the study. The women walked on treadmills at the laboratory three times per week for 30 minutes at a pace that represented about 80 percent of their maximum endurance.

They continued the program for 12 weeks, with the scientists repeating the original fitness and other tests every month during that time.

At the end of 12 weeks, the women were all significantly more aerobically fit than they had been at the start. But many were fatter. Almost 70 percent of the women had added at least some fat mass during the program, and several had gained as much as 10 pounds, most of which was from fat, not added muscle.

A few of the women, though, had lost that much fat or more, and quite a few had remained at the same weight as at the start of the regimen.

At this point, the researchers returned to the data from the first day of the study, to determine whether any obvious differences existed between the women who subsequently gained or lost weight. “Some past studies of dieting had indicated that women who weigh more at the beginning” of a weight-loss program “tend to lose more weight during the program,” Dr. Gaesser said.

But the researchers found no correlation in this case between a woman’s weight at the start and end of the study. In fact, the scientists found no connection between any of the original parameters of health and fitness and the women’s responses to the exercise program.

But looking deeper into their data, they discovered one interesting indicator: Those women who were losing weight after four weeks of exercise tended to continue to lose weight, while the others did not.
“What that means in practical terms is that someone who wants to lose weight with exercise” should step on the bathroom scale after a month, Dr. Gaesser said. If at that point your weight remains stubbornly unchanged or has increased, “look closely at your diet and other activities,” he said.

While this study didn’t track the women’s eating and movement habits away from the lab, it is likely that those who gained weight began eating more and moving less when they weren’t on the treadmills, “probably without meaning to,” Dr. Gaesser said.

Of course, the study was fairly short-term. It also did not involve men, although some past studies indicate that men, like women, frequently add fat mass after starting to exercise.

Still, the results, while sobering in some respects, also provide encouragement. By deploying a bathroom scale and discipline, along with exercise, you may well lose weight, Dr. Gaesser said.

Even more important, the women in the study were much fitter after four months of exercise, and Dr. Gaesser said “fitness matters far more for health than how much you weigh.”

Monday, November 10, 2014

Big business or small, innovation can be hard to come by. But its the ability to recognize where insight comes from that helps business stay healthy. Too much daily analytics and often times not enough recognition of the intuitiveness of the innovator within your company can lead to missed opportunities. For there to be healthy growth, it's as important to hire the creators as it is the bean-counters. A Harvard Business Review article discusses how insight comes about.

Harvard Business ReviewCustomers

Where to Look for Insight


R1411H_A
Matt Chase
 
Hear the word “innovation,” and you might think of an R&D lab, a design group, or a start-up venture. But today innovators are in demand everywhere—from the factory floor to the salesroom, the IT help desk to the HR department, the employee cafeteria to the C-suite. Innovation isn’t a department. It’s a mindset that should permeate your entire enterprise.

No matter the venue, the feedstock for innovation is insight—an imaginative understanding of an internal or external opportunity that can be tapped to improve efficiency, generate revenue, or boost engagement. Insights can be about stakeholder needs, market dynamics, or even how your company works.

Several Fortune 500 companies have been founded on a single insight about what customers want. Starbucks brought a little bit of Italy to coffee shops. Home Depot gave do-it-yourselfers access to professional supplies. The Body Shop was built on the notion that buyers of beauty products care about humane animal-testing practices. Inside your company, insights can lead to more-efficient operations, simplified processes, or leaner structures.

Insights can be powerful, but how do you find them? Should you brainstorm with colleagues? Sift through masses of data? Simply introspect? Or carry on as usual and wait for the proverbial apple to fall on your head?

In our combined half-century of working with innovators at start-ups and within large corporations, we’ve found that the best insights tend to come from sources that can be categorized. We recognize that many people arrive at great ideas more or less serendipitously, but we nevertheless believe that it’s possible for individuals to approach innovation in a more systematic way.

On the basis of our experiences with and research into entrepreneurial ventures and product-development groups in varied industries around the world, we have outlined seven “insight channels” that can be used by would-be innovators in any function or role. They are listed below. By periodically tuning in to these channels and methodically running through them, you can focus your imagination, organize thinking, spur creativity, and find valuable ideas for growth.
________________________________________________________________________________

Anomalies.

Businesses today are awash in data. Innovators pore over this information looking for promising ideas, but often they focus on means and averages, which lead to broad conclusions. Sometimes the real opportunities lie in the results that deviate from business as usual.

Consider an anomaly in global e-commerce. One might think that Russia, with more than 100 million middle-class consumers and 75 million internet subscribers, would be an attractive market for online retail. However, e-commerce accounts for a paltry 1.5% of total retail sales in the country. The entrepreneur Niels Tonsen recognized why: The Russian postal system is very unreliable, and few consumers have credit cards. This insight led Tonsen to create an online clothing store, Lamoda, which employs an army of couriers to deliver customers’ purchases to their homes, pick up cash on delivery, and even offer fashion advice. By providing an innovative experience that effectively brings the store, the style consultant, and the cash register to the customer’s front door, Lamoda built a very successful e-commerce business, uniquely suited to the Russian market. (See also “The CEO of Ozon on Building an e-Commerce Giant in a Cash-Only Economy,” HBR, July–August 2014.)

The smart innovator knows to notice and then follow up on surprising data. To look for anomalies, ask questions such as: Is your market share or revenue abnormally low or high in a geographical market? Are you having unusual success with a specific customer segment? Are some of your salespeople unusually productive? Are some of your suppliers able to deliver unusually quickly? Then dig deeper. The deviant numbers may be the tip of the iceberg, hiding a valuable insight below.

Confluence.

When several trends come together, their intersection can be fertile ground for insights. For instance, the confluence of mobile telephony growth, social networking, and increasingly short attention spans has spurred the creation of social media applications including Vine, which allows the sharing of short videos; Tinder, a GPS-linked matchmaker; and Snapchat, which deletes anything sent through it from the receiver’s phone in a matter of seconds. Evan Spiegel and his Snapchat cofounders built on two more-specific social media trends: the urge to broadcast life as it happens and growing concerns over privacy. People express themselves spontaneously on Snapchat without worrying about self-censorship.

New social habits, technologies, and areas of interest are forming all the time across all facets of life. The smart innovator looks at how they fit together. Ask yourself: What are the major economic, demographic, and technological trends affecting my organization, industry, or market? How do those trends intersect? For instance, if you combine an aging population (a demographic trend) with mobile connectivity (a technology trend) and rising health care costs (an economic trend), you can mine the intersection to create services such as remote health care monitoring for seniors. Similarly, if you combine the rising costs and difficulty of sourcing talent with the widespread availability of mobile video, you can see an opportunity to create a video-based recruitment application to screen a large number of candidates at a low cost.

Frustrations.

Life’s irritations are often a terrific source of ideas. In the late 1990s Mark Vadon, a young consultant, went shopping for an engagement ring and found the experience intimidating and difficult. The system for categorizing and valuing diamonds is complicated, and eager salespeople only add to the pressure. Vadon reasoned that many other men were equally put off—an insight that led him in 1999 to found Blue Nile, an online jewelry dealer that offers useful tutorials and information on gems. Today the company is the largest online retailer of diamonds and sells some $250 million worth of engagement rings a year—more than 4% of total sales in the U.S. market.
Many people arrive at great ideas more or less serendipitously—but it’s possible for individuals to approach innovation in a more systematic way.

Vadon’s experience shows the value of paying attention to what annoys people and then fixing the problem. Put yourself in the shoes of customers, colleagues, or suppliers and ask: What’s most frustrating about your products, processes, or workplace? What bothers you personally about your business? What work-arounds do people use to get their jobs done? How could they be improved upon? Can you make customers’ lives easier or company meetings less painful? Can you reduce the hassles your suppliers face? If you feel people’s frustrations, you can find valuable innovation opportunities.

Orthodoxies.

When something has always been done the same way on your team or in your organization or industry, it’s worth asking if there’s an alternative. Traditions often block potential innovations because people are reluctant to abandon the tried-and-true. But when conditions change, so must traditions.

In the defense industry, for example, manufacturers have long focused on building expensive and sophisticated missiles, such as Raytheon’s Tomahawk, that sell for more than a million dollars; even the cheapest offerings, such as Lockheed’s Hellfire, cost upward of $100,000. These missiles are developed with customer funding (from the U.S. Department of Defense) and are custom-designed to be smart and powerful so that they can take out tanks and other large targets. But at Raytheon (a company to which Mohanbir Sawhney has provided consulting), the 25-year veteran Steve Ignat and his team recently upended that status quo.

Knowing that the United States and its allies needed cheaper, stealthier missiles to effectively target small groups of terrorists on the ground, they created a low-cost manufacturing facility (dubbed the Bike Shop) and, without even courting a single customer, used parts from existing production programs to assemble exactly those sorts of weapons. One of the missiles they built, the Griffin, is now in high demand.

Orthodoxies hide in every organization, industry, and market. To uncover them, ask yourself: What beliefs do we all hold sacred? Why do things have to be this way? What if the reverse were true? What opportunities would be opened up if we abandoned those assumptions and beliefs?

Extremities.

Businesses, appropriately, spend most of their time concerned with their mainstream stakeholders. But sometimes it is the “positive deviants,” as Oxford University’s Richard Pascale calls them, who are a rich source of ideas or insights, teaching us innovative ways to overcome incredible odds or solve seemingly intractable problems.

In May 2014 the famous Harvard law professor and activist Larry Lessig created Mayday, a political action committee to address the issue of corporate money in politics. The PAC would use community- and internet-based “crowdfunding” to raise similar amounts of money directly from citizens. As of August 25, 2014, it had raised $7.92 million from more than 55,000 contributors.
Positive deviants may be visionary customers who can help you see trends before they become mainstream. They may be manic coworkers who are passionate and don’t take no for an answer. They may be enlightened shareholders who can help shape your company’s strategy. Innovators must look at the fringes of stakeholder groups and ask: What can we learn from those who are most intense in their complaints or enthusiasm that we could apply to our company or our role?

Voyages.

When business turns stale, innovators get out of their own offices to visit “customers”—whether that means employees they manage, colleagues who rely on their work product, or the people who buy their goods and services. These “voyages” into different worlds are necessary because all behavior takes place within a rich sociocultural context; it’s impossible to understand what others are thinking when you’re sitting alone at your desk. Designers and product developers have long understood how important it is to take this anthropological approach.

A few years ago, Jennifer Hargreaves, a manager at the financial software company Intuit, was tasked with creating a new version of the company’s popular QuickBooks product for nonprofit organizations. Her first step was to volunteer at a local charity. After immersing herself in the new context—helping to manage the organization’s accounts for a few months—she noticed sharp differences between for-profit and nonprofit financial management processes. The focus was fundraising, not sales, and donors, not customers. This on-the-ground research helped her brainstorm extra features—such as the ability to track donations, pledges, and grants separately and to allocate expenses to particular initiatives or programs—for the new QuickBooks Premier Nonprofit, which she later launched to positive reviews and sales.

Anyone can make similar voyages. Learn how your stakeholders live, work, and behave. Ask yourself: What are the social, cultural, and environmental factors that affect their preferences and behaviors? How can we create solutions that respond to those factors?

Analogies.

Sometimes other teams, business units, companies, or industries have adopted useful ideas or systems that haven’t crossed the border, so to speak. Can you import innovation—even from a place that seems far removed or exotic?

Greg Lambrecht came up with his Coravin Wine Access System by co-opting ideas from the world of surgery. An MIT-trained engineer and an oenophile, he grew tired of uncorking bottles that he didn’t want to finish in one night, only to have the fine wine start to oxidize and deteriorate. Wouldn’t it be wonderful to be able to drink just one glass while leaving the rest perfectly preserved? He knew that surgeons had started using extra-fine needles to ensure minimally invasive surgery and wondered if the same type of needles could be used to draw wine from a bottle. He tested and developed the idea over more than a decade, and despite a few setbacks, Coravin has been well reviewed and is now widely available.

We advise innovators to study a wide range of unrelated functional groups and industries to look for analogies that they can adapt to their domains. After all, innovation is not about bringing something new into the world. It’s about usefully applying something that is new to the situation, no matter the purpose for which it was invented.Our list of insight channels has evolved over the years and will no doubt continue to change and grow. Other observers could probably add a few categories of their own. But we’ve consistently found in our research and work that these seven are powerful drivers of innovation. Although they’re most commonly used by entrepreneurs, developers, and designers, they can help you in any role and any context where new thinking is required. Few people find great ideas on a blank canvas. Most of us need our imaginations channeled.


Mohanbir Sawhney (mohans@kellogg.northwestern.edu) is the McCormick Tribune Professor of Technology and the director of the Center for Research in Technology and Innovation at Northwestern University’s Kellogg School of Management, in Evanston, Illinois. They are the authors of a book on network-centric innovation (coming in October from Wharton School Publishing).

Sanjay Khosla is a senior fellow at Kellogg and was formerly the president of developing markets for Kraft Foods (now Mondelēz International). They are the coauthors of Fewer, Bigger, Bolder: From Mindless Expansion to Focused Growth (Portfolio, 2014).

Tuesday, November 4, 2014

With more States considering the legalization of marijuana, does the new "designer pot" with its greater potency have a greater health impact on users? Considering most studies supporting marijuana use were conducted years ago when pot-potency was less, should any recommendation for legalization first consider more current study outcomes? A NY Times Health story asks the questions.



The gray matter of the nucleus accumbens, the walnut-shaped pleasure center of the brain, was glowing like a flame, showing a notable increase in density. “It could mean that there’s some sort of drug learning taking place,” speculated Jodi Gilman, at her computer screen at the Massachusetts General Hospital-Harvard Center for Addiction Medicine. Was the brain adapting to marijuana exposure, rewiring the reward system to demand the drug?

Dr. Gilman was reviewing a composite scan of the brains of 20 pot smokers, ages 18 to 25. What she and fellow researchers at Harvard and Northwestern University found within those scans surprised them. Even in the seven participants who smoked only once or twice a week, there was evidence of structural differences in two significant regions of the brain. The more the subjects smoked, the greater the differences.

Moderate marijuana use by healthy adults seems to pose little risk, and there are potential medical benefits, including easing nausea and pain. But it has long been known that, with the brain developing into the mid-20s, young people who smoke early and often are more likely to have learning and mental health problems. Now researchers suggest existing studies are no longer sufficient. Much of what’s known is based on studies conducted years ago with much less powerful pot.

A Harvard-Northwestern study has found differences between the brains of young adult marijuana smokers and those of nonsmokers. In these composite scans, colors represent the differences — in the shape of the amygdala, top, and nucleus accumbens. Yellow indicates areas that are most different, red the least. Credit The Journal of Neuroscience

Marijuana samples seized by the federal Drug Enforcement Agency show the concentration of THC, the drug’s psychoactive compound, rising from a mean of 3.75 percent in 1995 to 13 percent in 2013. Potency seesaws depending on the strain and form. Fresh Baked, which sells recreational marijuana in Boulder, Colo., offers “Green Crack,” with a THC content of about 21 percent, and “Phnom Penh,” with about 8 percent. The level in a concentrate called “Bubble Hash” is about 70 percent; cartridges for vaporizers, much like e-cigarettes, range from 15 to 30 percent THC.

High-THC marijuana is associated with paranoia and psychosis, according to a June article in The New England Journal of Medicine. “We have seen very, very significant increases in emergency room admissions associated with marijuana use that can’t be accounted for solely on basis of changes in prevalence rates,” said Nora D. Volkow, director of the National Institute on Drug Abuse and a co-author of the THC study. “It can only be explained by the fact that current marijuana has higher potency associated with much greater risk for adverse effects.” Emergency room visits related to marijuana have nearly doubled, from 66,000 in 2004 to 129,000 in 2011, according to the Substance Abuse and Mental Health Services Administration.

Higher potency may also accelerate addiction. “You don’t have to work so hard to get high,” said Alan J. Budney, a researcher and professor at Dartmouth’s medical school. “As you make it easier to get high, it makes a person more vulnerable to addiction.” Among adults, the rate is one of 11; for teenagers, one of six.

Concerns over increasing potency, and rising usage among the young, is giving new urgency to research.

For the Harvard-Northwestern study, published in the April issue of The Journal of Neuroscience, the team scanned the brains of 40 young adults, most from Boston-area colleges. Half were nonusers; half reported smoking for one to six years and showed no signs of dependence. Besides the seven light smokers, nine used three to five days a week and four used, on average, daily. All smokers showed abnormalities in the shape, density and volume of the nucleus accumbens, which “is at the core of motivation, the core of pleasure and pain, and every decision that you make,” explained Dr. Hans Breiter, a co-author of the study and professor of psychiatry and behavioral sciences at Northwestern’s medical school.

Similar changes affected the amygdala, which is fundamental in processing emotions, memories and fear responses.

What is already known is that in casual users, THC can disrupt focus, working memory, decision making and motivation for about 24 hours. “The fact that we can see these structural effects in the brain could indicate that the effects of THC are longer lasting than we previously thought,” said Dr. Gilman, an instructor in psychology at Harvard’s medical school.

The study was preliminary and small, and attempts to replicate it are underway. Meanwhile, Dr. Gilman is trying to figure out how the findings relate to brain function and behavior.

One day in September, she was assessing Emma, a student who said her smoking — almost every day — didn’t interfere with school, work or other obligations. For $100 to go toward study-abroad plans, Emma politely plowed through nearly three hours of tests on cognitive functions that are or might be affected by THC, like the ability to delay gratification (would it be better to have $30 tonight or $45 in 15 days?) and motivation (a choice between computer games, the harder one offering a bigger payoff). For memory, Emma listened to lists of words, repeating back those she recalled. Next came risk. Would she bungee jump? Eat high-cholesterol food? (“These kids tend to be risk takers, particularly with their own health and safety,” Dr. Gilman said.)

A final test: Did Emma crave a joint? Her response: somewhat.

Dr. Gilman is concerned about pot’s impact on the college population. “This is when they are making some major life decisions,” she said, “choosing a major, making long-lasting friendships.”

Dr. Volkow noted another problem: Partying on a Saturday night may hinder studying for a test or writing a paper due on Monday. “Maybe you won’t have the motivation to study, because there’s no reward, no incentive,” she said.

Evidence of long-term effects is also building. A study released in 2012 showed that teenagers who were found to be dependent on pot before age 18 and who continued using it into adulthood lost an average of eight I.Q. points by age 38. And last year at Northwestern, Dr. Breiter and colleagues also saw changes in the nucleus accumbens among adults in their early 20s who had smoked daily for three years but had stopped for at least two years.

They had impaired working memories as well. “Working memory is key for learning,” Dr. Breiter said. “If I were to design a substance that is bad for college students, it would be marijuana.”

Abigail Sullivan Moore is co-author of “The iConnected Parent: Staying Close to Your Kids in College (and Beyond) While Letting Them Grow Up.”