Sometimes, adolescents just can’t resist

Don’t get mad the next time you catch your teenager texting when he promised to be studying.

He simply may not be able to resist.

A University of Iowa study found teenagers are far more sensitive than adults to the immediate effect or reward of their behaviors. The findings may help explain, for example, why the initial rush of texting may be more enticing for adolescents than the long-term payoff of studying.

“The rewards have a strong, perceptional draw and are more enticing to the teenager,” says Jatin Vaidya, a professor of psychiatry at the UI and corresponding author of the study, which appeared online this week in the journal Psychological Science. “Even when a behavior is no longer in a teenager’s best interest to continue, they will because the effect of the reward is still there and lasts much longer in adolescents than in adults.”

For parents, that means limiting distractions so teenagers can make better choices. Take the homework and social media dilemma: At 9 p.m., shut off everything except a computer that has no access to Facebook or Twitter, the researchers advise.

“I’m not saying they shouldn’t be allowed access to technology,” Vaidya says. “But they need help in regulating their attention so they can develop those impulse-control skills.”

In their study, “Value-Driven Attentional Capture in Adolescence,” Vaidya and co-authors Shaun Vecera, a professor of psychology, and Zachary Roper, a graduate student in psychology, note researchers generally believe teenagers are impulsive, make bad decisions, and engage in risky behavior because the frontal lobes of their brains are not fully developed.

But the UI researchers wondered whether something more fundamental was going on with adolescents to trigger behaviors independent of higher-level reasoning.

“We wanted to try to understand the brain’s reward system and how it changes from childhood to adulthood,” says Vaidya, who adds the reward trait in the human brain is much more primitive than decision-making. “We’ve been trying to understand the reward process in adolescence and whether there is more to adolescent behavior than an under-developed frontal lobe,” he adds.

For their study, the researchers recruited 40 adolescents, ages 13 and 16, and 40 adults, ages 20 and 35. First, participants were asked to find a red or green ring hidden within an array of rings on a computer screen. Once identified, they reported whether the white line inside the ring was vertical or horizontal. If they were right, they received a reward between 2 and 10 cents, depending on the color. For some participants, the red ring paid the highest reward; for others, it was the green. None was told which color would pay the most.

After 240 trials, the participants were asked whether they noticed anything about the colors. Most made no association between a color and reward, which researchers say proves the ring exercise didn’t involve high-level, decision-making.

In the next stage, participants showed they had developed an intuitive association when they were asked to find a diamond-shaped target. This time, the red and green rings were used as decoys.

At first, the adolescents and adults selected the color ring that garnered them the highest monetary reward, the goal of the first trial. But in short order, the adults adjusted and selected the diamond. The adolescents did not.

Even after 240 trials, the adolescents were still more apt to pick the colored rings.

“Even though you’ve told them, ‘You have a new target,’ the adolescents can’t get rid of the association they learned before,” Vecera says. “It’s as if that association is much more potent for the adolescent than for the adult.

“If you give the adolescent a reward, it will persist longer,” he adds. “The fact that the reward is gone doesn’t matter. They will act as if the reward is still there.”

Researchers say that inability to readily adjust behavior explains why, for example, a teenager may continue to make inappropriate comments in class long after friends stopped laughing.

In the future, researchers hope to delve into the psychological and neurological aspects of their results.

“Are there certain brain regions or circuits that continue to develop from adolescence to adulthood that play role in directing attention away from reward stimuli that are not task relevant?” Vaidya asks. “Also, what sort of life experiences and skill help to improve performance on this task?”

Learning Early in Life May Help Keep Brain Cells Alive

Using your brain – particularly during adolescence – may help brain cells survive and could impact how the brain functions after puberty.

According to a recently published study in Frontiers in Neuroscience, Rutgers behavioral and systems neuroscientist Tracey Shors, who co-authored the study, found that the newborn brain cells in young rats that were successful at learning survived while the same brain cells in animals that didn’t master the task died quickly.

“In those that didn’t learn, three weeks after the new brain cells were made, nearly one-half of them were no longer there,” said Shors, professor in the Department of Psychology and Center for Collaborative Neuroscience at Rutgers. “But in those that learned, it was hard to count. There were so many that were still alive.”

The study is important, Shors says, because it suggests that the massive proliferation of new brain cells most likely helps young animals leave the protectiveness of their mothers and face dangers, challenges and opportunities of adulthood.

Scientists have known for years that the neurons in adult rats, which are significant but fewer in numbers than during puberty, could be saved with learning, but they did not know if this would be the case for young rats that produce two to four times more neurons than adult animals.

By examining the hippocampus – a portion of the brain associated with the process of learning – after the rats learned to associate a sound with a motor response, scientists found that the new brain cells injected with dye a few weeks earlier were still alive in those that had learned the task while the cells in those who had failed did not survive.

“It’s not that learning makes more cells,” says Shors. “It’s that the process of learning keeps new cells alive that are already present at the time of the learning experience.”

Since the process of producing new brain cells on a cellular level is similar in animals, including humans, Shors says ensuring that adolescent children learn at optimal levels is critical.

“What it has shown me, especially as an educator, is how difficult it is to achieve optimal learning for our students. You don’t want the material to be too easy to learn and yet still have it too difficult where the student doesn’t learn and gives up,” Shors says.

So, what does this mean for the 12-year-old adolescent boy or girl?

While scientists can’t measure individual brain cells in humans, Shors says this study, on the cellular level, provides a look at what is happening in the adolescent brain and provides a window into the amazing ability the brain has to reorganize itself and form new neural connections at such a transformational time in our lives.

“Adolescents are trying to figure out who they are now, who they want to be when they grow up and are at school in a learning environment all day long,” says Shors. “The brain has to have a lot of strength to respond to all those experiences.”

Oxytocin gene partly responsible for how adolescents feel in company

Loneliness: could there be a genetic explanation for it? Yes, to some extent! At least in the case of young female adolescents who, it appears, are more likely to feel lonely in everyday life if they have a specific variant of the gene that regulates how oxytocin – also known as the ‘bonding hormone’ – is received in the brain. Boys who carry this variant are not lonelier but, like girls, respond more strongly to a negative social environment. These findings were published this week in the academic journal PlosONE.

Oxytocin is a hormone with an important role in social behaviour. In the period following birth, it is an important factor in the bonding process between mother and baby, but it also has an influence on other relationships. The gene that regulates oxytocin-sensitivity in the brain varies between one person and another. Some people are less sensitive to oxytocin and therefore more likely to feel lonely. Various indicators have already suggested this. This prompted a group of behavioural researchers in Nijmegen to carry out a fresh and in-depth study of oxytocin effects in a group in which ‘belonging’ is of paramount importance: young adolescents.

A large group, frequently surveyed

The study involved 278 adolescents, 58 per cent of whom were girls. They were contacted via their smartphones nine times a day over a six-day period and asked to report how they felt and who they were with. The presence of the variant of the oxytocin receptor gene OXTR was also determined. ‘This is a new approach to researching the interaction between gene variation and the environment,’ explains Eeske van Roekel, the lead author of the article published online in PlosONE on Monday 4 November. ‘By asking the subjects nine times a day “How do you feel? Who are you with? What do you think of the people you are with?,” we managed to put together a clear picture of how adolescents feel in everyday life. These real-time reports are more reliable than responses after the event.’

Lonelier with specific OXTR variant

‘Our most important finding was that girls who carried a certain variant of the oxytocin gene in their DNA felt lonelier than girls who did not. Boys with this variant were also adversely affected by negative company at the weekend: their feelings increased the longer they were in such company, while boys without this variant were unaffected. These findings apply to both boys and girls.’ The measured effects are small but still relevant, says Van Roekel. ‘These methods reveal more about actual everyday experiences than methods that ask people once at a later date to describe how they felt.’ Heightened sensitivity to negative company in the case of this specific variant was only visible at weekends. How can that be explained? ‘We surmise that it’s because you have more freedom in the weekend to choose the people you mix with than through the week,’ says Van Roekel. ‘Then it makes a deeper impression if they treat you in a negative manner.’

New trend

No-one knows yet exactly how the receptor gene works. ‘We still don’t know how it translates into, for example, oxytocin levels in the brain,’ says Van Roekel. ‘So more research is needed on that front.’ Research on connections between genes and behaviour is developing gradually. ‘We think that our approach, which takes multiple measurements in the daily life of adolescents, has a lot to offer when it comes to discovering connections.’ Van Roekel conducted her research in the group of Professor Rutger Engels at the Behavioural Science Institute of Radboud University Nijmegen.

Perception of Marijuana as a “Safe Drug” Is Scientifically Inaccurate

The nature of the teenage brain makes users of cannabis amongst this population particularly at risk of developing addictive behaviors and suffering other long-term negative effects, according to researchers at the University of Montreal and New York’s Icahn School of Medicine at Mount Sinai.

“Of the illicit drugs, cannabis is most used by teenagers since it is perceived by many to be of little harm. This perception has led to a growing number of states approving its legalization and increased accessibility. Most of the debates and ensuing policies regarding cannabis were done without consideration of its impact on one of the most vulnerable population, namely teens, or without consideration of scientific data,” wrote Professor Didier Jutras-Aswad of the University of Montreal and Yasmin Hurd, MD, PhD, of Mount Sinai. “While it is clear that more systematic scientific studies are needed to understand the long-term impact of adolescent cannabis exposure on brain and behavior, the current evidence suggests that it has a far-reaching influence on adult addictive behaviors particularly for certain subsets of vulnerable individuals.”

The researchers reviewed over 120 studies that looked at different aspects of the relationship between cannabis and the adolescent brain, including the biology of the brain, chemical reaction that occurs in the brain when the drug is used, the influence of genetics and environmental factors, in addition to studies into the “gateway drug” phenomenon. “Data from epidemiological studies have repeatedly shown an association between cannabis use and subsequent addiction to heavy drugs and psychosis (i.e. schizophrenia). Interestingly, the risk to develop such disorders after cannabis exposure is not the same for all individuals and is correlated with genetic factors, the intensity of cannabis use and the age at which it occurs. When the first exposure occurs in younger versus older adolescents, the impact of cannabis seems to be worse in regard to many outcomes such as mental health, education attainment, delinquency and ability to conform to adult role,” Dr Jutras-Aswad said.

Although it is difficult to confirm in all certainty a causal link between drug consumption and the resulting behavior, the researchers note that rat models enable scientists to explore and directly observe the same chemical reactions that happen in human brains. Cannabis interacts with our brain through chemical receptors (namely cannabinoid receptors such as CB1 and CB2.) These receptors are situated in the areas of our brain that govern our learning and management of rewards, motivated behavior, decision-making, habit formation and motor function. As the structure of the brain changes rapidly during adolescence (before settling in adulthood), scientists believe that the cannabis consumption at this time greatly influences the way these parts of the user’s personality develop. In adolescent rat models, scientists have been able to observe differences in the chemical pathways that govern addiction and vulnerability – a receptor in the brain known as the dopamine D2 receptor is well known to be less present in cases of substance abuse.

Only a minority (approximately one in four) of teenage users of cannabis will develop an abusive or dependant relationship with the drug. This suggests to the researchers that specific genetic and behavioral factors influence the likelihood that the drug use will continue. Studies have also shown that cannabis dependence can be inherited through the genes that produce the cannabinoid receptors and an enzyme involved in the processing of THC. Other psychological factors are also likely involved. “Individuals who will develop cannabis dependence generally report a temperament characterized by negative affect, aggressivity and impulsivity, from an early age. Some of these traits are often exacerbated with years of cannabis use, which suggests that users become trapped in a vicious cycle of self-medication, which in turn becomes a dependence” Jutras-Aswad said.

The researchers stress that while a lot remains unknown about the mechanics of cannabis abuse, the body of existing research has clear implications for society. “It is now clear from the scientific data that cannabis is not harmless to the adolescent brain, specifically those who are most vulnerable from a genetic or psychological standpoint. Identifying these vulnerable adolescents, including through genetic or psychological screening, may be critical for prevention and early intervention of addiction and psychiatric disorders related to cannabis use. The objective is not to fuel the debate about whether cannabis is good or bad, but instead to identify those individuals who might most suffer from its deleterious effects and provide adequate measures to prevent this risk” Jutras-Aswad said. “Continuing research should be performed to inform public policy in this area. Without such systematic, evidenced-based research to understand the long-term effects of cannabis on the developing brain, not only the legal status of cannabis will be determined on uncertain ground, but we will not be able to innovate effective treatments such as the medicinal use of cannabis plant components that might be beneficial for treating specific disorders,” Dr Hurd said.

(Image: AP)

Injuries From Teen Fighting Deal a Blow to IQ

New study explores connection between physical fights, cognitive decline

A new Florida State University study has found that adolescent boys who are hurt in just two physical fights suffer a loss in IQ that is roughly equivalent to missing an entire year of school. Girls experience a similar loss of IQ after only a single fighting-related injury.

The findings are significant because decreases in IQ are associated with lower educational achievement and occupational performance, mental disorders, behavioral problems and even longevity, the researchers said.

“It’s no surprise that being severely physically injured results in negative repercussions, but the extent to which such injuries affect intelligence was quite surprising,” said Joseph A. Schwartz, a doctoral student who conducted the study with Professor Kevin Beaver in FSU’s College of Criminology and Criminal Justice.

Their findings are outlined in the paper, “Serious Fighting-Related Injuries Produce a Significant Reduction in Intelligence,” which was published in the Journal of Adolescent Health. The study is among the first to look at the long-term effects of fighting during adolescence, a critical period of neurological development.

About 4 percent of high school students are injured as a result of a physical fight each year, the researchers said.

Schwartz and Beaver used data from the National Longitudinal Study of Adolescent Health collected between 1994 and 2002 to examine whether serious fighting-related injuries resulted in significant decreases in IQ over a 5- to 6-year time span. The longitudinal study began with a nationally representative sample of 20,000 middle and high school students who were tracked into adulthood through subsequent waves of data collection. At each wave of data collection, respondents were asked about a wide variety of topics, including personality traits, social relationships and the frequency of specific behaviors.

Perhaps not surprisingly, boys experienced a higher number of injuries from fighting than girls; however, the consequences for girls were more severe, a fact the researchers attributed to physiological differences that give males an increased ability to withstand physical trauma.

The researchers found that each fighting-related injury resulted in a loss of 1.62 IQ points for boys, while girls lost an average of 3.02 IQ points, even after controlling for changes in socio-economic status, age and race for both genders. Previous studies have indicated that missing a single year of school is associated with a loss of 2 to 4 IQ points.

The impact on IQ may be even greater when considering only head injuries, the researchers said. The data they studied took into account all fighting-related physical injuries.

The findings highlight the importance of schools and communities developing policies aimed at limiting injuries suffered during adolescence whether through fighting, bullying or contact sports, Schwartz said.

“We tend to focus on factors that may result in increases in intelligence over time, but examining the factors that result in decreases may be just as important,” he said. “The first step in correcting a problem is understanding its underlying causes. By knowing that fighting-related injuries result in a significant decrease in intelligence, we can begin to develop programs and protocols aimed at effective intervention.”

Marijuana use in adolescence may cause permanent brain abnormalities

Regular marijuana use in adolescence, but not adulthood, may permanently impair brain function and cognition, and may increase the risk of developing serious psychiatric disorders such as schizophrenia, according to a recent study from the University of Maryland School of Medicine. Researchers hope that the study, published in Neuropsychopharmacology — a publication of the journal Nature – will help to shed light on the potential long-term effects of marijuana use, particularly as lawmakers in Maryland and elsewhere contemplate legalizing the drug.

"Over the past 20 years, there has been a major controversy about the long-term effects of marijuana, with some evidence that use in adolescence could be damaging," says the study’s senior author Asaf Keller, Ph.D., Professor of Anatomy and Neurobiology at the University of Maryland School of Medicine. "Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent cognitive deficits, and have a significantly higher incidence of psychiatric disorders such as schizophrenia. There likely is a genetic susceptibility, and then you add marijuana during adolescence and it becomes the trigger."

"Adolescence is the critical period during which marijuana use can be damaging," says the study’s lead author, Sylvina Mullins Raver, a Ph.D. candidate in the Program in Neuroscience in the Department of Anatomy and Neurobiology at the University of Maryland School of Medicine. "We wanted to identify the biological underpinnings and determine whether there is a real, permanent health risk to marijuana use."

The scientists — including co-author Sarah Paige Haughwout, a research technician in Dr. Keller’s laboratory — began by examining cortical oscillations in mice. Cortical oscillations are patterns of the activity of neurons in the brain and are believed to underlie the brain’s various functions. These oscillations are very abnormal in schizophrenia and in other psychiatric disorders. The scientists exposed young mice to very low doses of the active ingredient in marijuana for 20 days, and then allowed them to return to their siblings and develop normally.

"In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities," says Ms. Raver. "We also found impaired cognitive behavioral performance in those mice. The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood."

The scientists repeated the experiment, this time administering marijuana ingredients to adult mice that had never been exposed to the drug before. Their cortical oscillations and ability to perform cognitive behavioral tasks remained normal, indicating that it was only drug exposure during the critical period of adolescence that impaired cognition through this mechanism. The researchers took the next step in their studies, trying to pinpoint the mechanisms underlying these changes and the time period in which they occur.

"We looked at the different regions of the brain," says Dr. Keller. "The back of the brain develops first, and the frontal parts of the brain develop during adolescence. We found that the frontal cortex is much more affected by the drugs during adolescence. This is the area of the brain controls executive functions such as planning and impulse control. It is also the area most affected in schizophrenia."

Dr. Keller’s team believes that the results have indications for humans as well. They will continue to study the underlying mechanisms that cause these changes in cortical oscillations. “The purpose of studying these mechanisms is to see whether we can reverse these effects,” says Dr. Keller. “We are hoping we will learn more about schizophrenia and other psychiatric disorders, which are complicated conditions. These cognitive symptoms are not affected by medication, but they might be affected by controlling these cortical oscillations.”

Teens’ Self-Consciousness Linked With Specific Brain, Physiological Responses

Teenagers are famously self-conscious, acutely aware and concerned about what their peers think of them. A new study reveals that this self-consciousness is linked with specific physiological and brain responses that seem to emerge in adolescence.

“Our study identifies adolescence as a unique period of the lifespan in which self-conscious emotion, physiological reactivity, and activity in specific brain areas converge and peak in response to being evaluated by others,” says psychological scientist and lead researcher Leah Somerville of Harvard University.

The findings, published in Psychological Science, a journal of the Association for Psychological Science, suggest that teens’ sensitivity to social evaluation might be explained by shifts in physiological and brain function during adolescence, in addition to the numerous sociocultural changes that take place during the teen years.

Somerville and colleagues wanted to investigate whether just being looked at — a minimal social-evaluation situation — might register with greater importance, arousal, and intensity for adolescents than for either children or adults. The researchers hypothesized that late-developing regions of the brain, such as the medial prefrontal cortex (MPFC), could play a unique role in the way teens monitor these types of social evaluative contexts.

The researchers had 69 participants, ranging in age from 8 to almost 23 years old, come to the lab and complete measures that gauged emotional, physiological, and neural responses to social evaluation.

They told the participants that they would be testing a new video camera embedded in the head coil of a functional MRI scanner. The participants watched a screen indicating whether the camera was “off,” “warming up,” or “on”, and were told that a same-sex peer of about the same age would be watching the video feed and would be able to see them when the camera was on. In reality, there was no camera in the MRI machine.

The consistency and strength of the resulting data took the researchers by surprise:

“We were concerned about whether simply being looked at was a strong enough ‘social evaluation’ to evoke emotional, physiological and neural responses,” says Somerville. “Our findings suggest that being watched, and to some extent anticipating being watched, were sufficient to elicit self-conscious emotional responses at each level of measurement.”

Specifically, participants’ self-reported embarrassment, physiological arousal, and MPFC activation showed reactivity to social evaluation that seemed to converge and peak during adolescence.

Adolescent participants also showed increased functional connectivity between the MPFC and striatum, an area of the brain that mediates motivated behaviors and actions. Somerville and colleagues speculate that the MPFC-striatum pathway may be a route by which social evaluative contexts influence behavior. The link may provide an initial clue as to why teens often engage in riskier behaviors when they’re with their peers.