Exploring the Adolescent Brain

Neuroscientists say adolescence is “a wonderful time.” Beleaguered parents may disagree.

“The adolescent brain isn’t broken or defective,” Dr. Jay Giedd told an audience at the American Association for the Advancement of Science (AAAS) on Wednesday. “It’s different from the child’s brain, and it’s different from the adult’s brain, but those differences have many upsides.”

In our digital age, for example, adolescents have a great advantage: “They’re old enough to master the technology, and young enough to embrace change,” Dr. Giedd said. Part of the difference is the teen brain’s extreme plasticity: New connections are being formed and others pruned at an astounding rate. This helps teens adapt quickly to any change in the environment (moving to the Arctic; learning a new computer operating system). [Watch video of the brain’s development based on fMRI images.]

Yet, this process also puts them in danger of “over-adapting,” which could potentially lead to serious illness. Psychoses, such as schizophrenia, for example, seem to appear more during adolescence than at other stages of life, said Dr. Giedd, chief of the Unit on Brain Imaging in the Child Psychiatry Branch at the National Institute for Mental Health.

Last spring we wrote about Dr. Giedd’s work on the how the teen brain changes, and he wrote a great explanatory piece for us in Cerebrum describing the double-edged sword that is this plasticity. New to me in this talk was the idea of comparing brain development to language. The basic senses (like sight, hearing), which develop at one of the earliest “sensitive periods” in life, might be considered the “letters” of cognition. Next, association areas come online, tying together the senses as we tie letters into words.

“By age 8 months, the letters are all there,” Dr. Giedd said, and as we grow, “the letters become words; the words become sentences. So the idea is, in schizophrenia, it’s not the words but the sentences” that go awry.

Fellow speaker Elaine Walker of Emory built on that idea. “We’re starting to describe [psychoses] as a brain degenerative process that’s occurring—a kind of ‘brain overshoot’ of the rapid-growth process Dr. Giedd described … It’s like a normal adolescent developmental trajectory that has been amplified over time.”

Her research also suggests that there may be signs as early as the “word” level that a child might be at risk for later psychoses. Examining home movies, researchers saw differences in movement and affect between children who later developed symptoms and their brothers and sisters who did not. “Long before the onset of the first psychotic symptoms, there were subtle abnormalities,” she said.

Showing us one video, she pointed out oddities in posture and in gait, how they held their hands when walking, and  specific errors in coordination. She also noted a rather flat affect, describing it as “a lack of emotional connectedness with his environment.” During the ‘sensitive period’ of adolescence, these children showed “a gradual onset of symptoms, and a decline in social and cognitive function,” she said.

The good news is that what we once considered a genetically determined disease may have a strong epigenetic component: The environment may trigger—or dampen—a psychotic illness, Walker said. Instead of a congenital illness, we might think
of psychoses as a congenital vulnerability, she suggested.

For example, “young adulthood is characterized by greater biological sensitivity to stress,” which increases levels of cortisol in the body, which “can affect the architecture of the brain, especially at vulnerable developmental stages” like adolescence, she said.

Dr. Walker’s lab is part of a consortium called NAPLS that is tracking a large group of people age 12 to 30 to find better ways to identify those who are at risk of developing a serious disorder and to discover ways to prevent it or stop it. Research is still in early stages, but she described some general findings. For one, at-risk kids are experiencing much more daily stress, and life stress (serious change that may have happened far earlier in life). “Stressful life events in the past seem  to set the stage for super-sensitivity to daily stress,” she said.

“We see much higher levels of cortisol in at-risk children, and even higher levels among those soon seen to develop  schizophrenia. We see a change in gray matter,” as Dr. Giedd’s research also showed, but in the opposite direction. “Those who convert to a psychotic disorder show much more pronounced decline in gray matter than those who do not.” In addition, individuals at risk who show more gray matter decline also show higher cortisol levels.

This all sounded dire to me, but really these findings “are making us more optimistic,” said Dr. Walker, who is also a member of the Dana Allliance for Brain Initiatives. “We have a lot more leverage for intervening to prevent the onset of psychosis than we ever had before. They do not have an unchangeable risk genotype, and now we’re seeing there are many potential avenues for intervention.”

Taking another angle on intervention, speaker Elizabeth Albro spoke of the challenges of translating cognitive  neuroscience into something teachers could use to help students learn. Albro, a commissioner at the Institute of Education  Sciences at the US Department of Education, described in-school studies trying to bridge the gap between what scientists have gleaned about learning from the quiet of their labs and what might actually work in the maelstrom that is classroom learning and lifelong learning.

They’ve seen some promising early results using biofeedback to improve attention when doing schoolwork and “interleaving” math problems (combining the new type of problem with types learned earlier) to improve retention.

“We’ve been using them to redesign curricula,” she said, keeping in mind that any one discrete action happens in an environment where many things are happening simultaneously. “The learning brain is working on these things all the time.”

The session was part of the Neuroscience and Society series, a partnership between the Dana Foundation and AAAS. A video of this session is at dana.org; videos of previous sessions are there, too: Neuroscience and the Law, and The Aging Brain: What’s New in Brain Research, Treatment, and Policy.

– Nicky Penttila

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