How Old is Old Enough?

An article in Governing entitled, What is the Age of Responsibility?, observes:

In most respects, people are considered adults at 18. That’s when they can vote and enter into legal contracts—including the purchase, if not rental, of a car. But a 20-year-old Marine, just back from patrolling the streets of Baghdad, would have to turn 21 before he could join a local police force in most cities in the United States. A 20-year-old college junior, far more educated than the average American, cannot buy alcohol or enter a casino. In 10 states, a single 20-year-old cannot legally have sex with a 17-year old. But in nearly every state, a 16-year-old can marry—if he has his parents’ permission.

With regard to juvenile justice, "in most states, a 10-year-old charged with murder can be tried as an adult."

But now some serious rethinking is going on. According to Governing:

Legislatures and courts are hearing a very different argument from a group of people that haven’t traditionally testified before them: neuroscientists. Using advanced brain-scanning technology, scientists are getting a better view of how the human brain develops than ever before. And what they’ve found is that in most people, the prefrontal cortex and its links to other regions of the brain are not fully formed until age 25—much later than anyone had realized. These areas are the seat of “executive decision making”—the parts of the brain that allow people to think through the likely consequences of an action, weigh the risks and benefits and stop themselves from acting on impulse. In other words, the stuff that makes you a mature person.

I had the opportunity last year to talk with scientists first hand on brain development. Or, rather, I stumbled into it. This from a Knowledge is Necessity blog piece late March, 2009:

Another full day at the International Congress on Schizophrenia Research, here in San Diego. To recap:

Breakfast: Beatriz Luna of the University of Pittsburgh tells me she isn't a schizophrenia researcher. Rather, she's into something called "development." I'm thinking development, as in a child psychologist.

No, she tells me. This is about brain development, as in the child brain maturing into the adult brain. She will be one of the speakers at a two-hour symposium later in the morning. Curious, I check it out:

Think of research into normal brain development shedding valuable light on schizophrenia, and, by extension, all of mental illness. The first speaker, Patricio O'Donnell of the University of Maryland, talks about cortical microcircuits and the balance between excitation and inhibition. Dopamine, he says, plays a large role in the modulation of circuits in the prefrontal cortex. During adolescence, he explains, these circuits experience dramatic connecting changes.

For instance, "phasic dopamine" (firing in bursts) gets dialed in, with improved signal to noise ratios.

But suppose the brain doesn't mature? Are we then looking at an approximation of schizophrenia?

David Lewis of the University of Pittsburgh shows slides that highlight the neuron's "dendritic spines." These spines play a major role in brain cells talking to one another. We know that people with schizophrenia are not favorably endowed in this category, but what does it mean?

In normal brain development, he explains, there is an early dramatic increase in spine density followed by a dropping off in adolescence and leveling out in adulthood. But are we talking about a drop-off in "functionally mature" or "functionally immature" connections? In other words, when the brain experiences structural changes, are the right chemical messages crossing the dendritic divide or the wrong ones?

Early intervention, he says, might be directed at enhancing the normal development of these synapses.

Dr Luna informs the audience that adolescence involves major risk of mental illness. As she explained to me over breakfast, this is when the brain changes gears. But what if something goes wrong in the transition? Might this underlie the pathology of mental illness?

During adolescence, the brain undergoes "synaptic pruning," along with axonal "myelination." In essence, brain function becomes more equally distributed, with less reliance on impulses from the basal ganglia and other more primitive regions of the brain.

But what if something goes wrong? Normal child brain function is suddenly not so normal, not in an adult brain anyway. You can kind of see this with the current economic meltdown, Dr Luna explains. It's a new world. AIG and GM and the rest can't behave the way they used to. The failure in executive behavior in this new context, she concludes, now becomes obvious.

The article in Governing notes that lawmakers are not going to exactly change the age of majority to 25 across the board. But there is room for nuanced legislation, say for raising the age for treating minors as adults in the criminal justice system and for lowering the drinking age (to paradoxically discourage binge drinking).

“Graduated driver licensing” (GDL) places conditions on teens behind the wheel. Some form of GDL has been implemented in nearly all states, with corresponding reductions in youth road accidents, fatalities, and injuries.

Yesterday, I put my 19-year-old nephew on a plane back to Connecticut after five or six days here with me in southern CA. He was a delight to have, and very easy to talk with. At his age, I was probably ahead in the book knowledge department, but would have been no match for him in social skills and insights into human nature. This kid was way more perceptive than adults twice or three times his age, and we were able to constructively discuss sensitive family issues adult-to-adult.

At the same time, I was able to openly acknowledge the 19-year-old in both of us. I'm single. I'm male. I don't always think with my brain. With reference to my age-gender cohort, I told him, we're all basically 19-year-old frat boys. The only difference is men my age (60) are physically falling apart.

In regard to some areas of our lives, we never attain the age of 21. Thank God for that.