Saturday February 21, 2015

Kidults: Does delaying responsibility affect our brains?

Adult daughter sitting between senior couple on settee

Adult daughter sitting between senior couple on settee (Getty Images)

Listen 7:57

New research suggests that real adulthood begins around age 25 because neurological changes are still occurring that could be due to delaying big responsibilities like marriage, parenthood and mortgages. Beatriz Luna, a professor of Psychiatry and Psychology at the University of Pittsburgh in Pennsylvania, discusses the findings.

So what is happening, neurologically, to delay adulthood now to the mid-20s?
What we're seeing in the latest findings are two things: number one, the prefrontal cortex, which supports planning, complex cognition and so forth, that's already there. It's the limbic system, which supports motivation and reward and enthusiasm and novelty-seeking, which we had thought was peaking during adolescence, that seems to continue to increase its hyperactivity all the way through the beginning of the 20s. 

Why do you think this is happening now? 
Well, I'll give you my opinion. I don't think it's a bad thing necessarily. I think that in Western society, we have the luxury to provide a safeguard for 20-somethings when they go to college. We support them, we pay their tuition, and many times we find ways for them to get loans. They have a much more extended, protected period where they don't have to immediately assume responsibilities. The brain is taking advantage of this period to continue to specialize. The longer time you have to affect your brain, to fit its environment, the better because the basis of development during this period is to find which are the best connections that will fit the environmental demands. If you stop that very quickly, you're not going to have as much variability and plasticity at the end of the day. 

But why did it stop before? What was shutting down the limbic action before, when people had different kinds of lives?
Well I think it was the fact that all of a sudden you were married by 19, you had children already, you had a job, and you had huge responsibilities. Novelty seeking and exploration are not going to support your survival if those are your circumstances. 

Right, so what are positives now for people delaying adulthood and having both of these parts of the brain working at top capacity?
What happens now, you really have the ability to explore and, number one, find what it is that you really want to do the rest of your life, and who is it that you want to spend the rest of your life with. As you know, the divorce rates have been incredibly high in the past few generations, and the hope is that now they can afford to have this ability, to be picky and really find their own trajectories, and that it will lead to better survival. 

What about the things that we associate with the developing brain, like the capacity for learning languages, or a musical instrument. Does the window stay open longer for that now? 
I don't know about that. I think that's a really great question. There are different levels of plasticity. The truth is, that the brain is plastic throughout your lifespan. For example, the hippocampus, which is a part of the brain where memory is involved and it supports other functions as well, continues to change into the 60s. That plastic capacity is there, but to different levels. New languages and so forth, that really entails a level of pruning, of being able to get rid of connections and specify connections that's available much earlier in development. But there's still some adjustment that can occur there. 

So you've outlined what the advantages are of having this super-active brain, but what could be the downside of delaying the onset of adulthood, neurologically?
Some of those things could be that you enjoy it so much that you never make that transition to having responsibility. That's something that's discussed, that you might miss the train, for example.

So you'll end up like the Dude in The Big Lebowski.
You've got it, exactly. Nothing wrong with that. [Laughs].

But if people are hitting their adulthood around 25, what does that mean for people in their 30s and 40s? 
Well, in their 30s and 40s, they're starting to have children. At this point when they're having children, they have reached such a greater level of specialization of the ability for the prefrontal brain to talk to the limbic brain, that it might make them better parents.

Mother and child in Kruger's Pumpkin Patch via photopin

(Kruger's Pumpkin Patch 2010 via photopin license)

Does it affect young people's emotional maturity? Does it affect their judgment?
Part of this maturation of these two aspects of brain processing is the ability to control your emotions. One of the things that many of us see, including in my laboratory, is the connectivity between the limbic systems and the prefrontal regions is changing dramatically. The white matter, the actual structural connections between brain regions, that continues to mature into the 30s, even. So this ability to be able to control your emotions is definitely improving all throughout the 20s, and into the 30s.

Beatriz, is this the first time in our evolutionary history that we've been able to delay adulthood so late in life?
I do believe that this is something new. The way that I like to think about it is not to judge it. It's not good or bad. It is what it is, and as you can see, this is something that is characterizing the highly developed societies. It's part of evolution. Another aspect is, the brain is not making judgments. It's not trying to be a good person or a bad person. It is just so beautifully constructed to adapt itself to the environmental demands. It just so happens in these richer, more developed societies, things have evolved to a point where they can support and sustain a longer developmental trajectory. That's wonderful. 

Do you think that that trajectory will continue? Will people's brains be adapting to adulthood later and later in life?
I don't know if later and later. The nature of the adaptation is a little bit different. A lot of growth is occurring from childhood to adolescence, but from adolescence to the mid-20s, it's a slower rate of change, and qualitatively different, because all the systems are already there. It's more a process of fine-tuning what's already there. I don't think this will continue forever. There are other biological time clocks that can determine the length of certain periods of plasticity.