At last, Stanford psychologists have come up with an explanation for our 20s. Or at least my 20s. That period of time when I was in so many ways an adult and yet some higher processing – inpulse control, for example – did not yet seem fully formed.
A group led by psychologist Brian Wandell, PhD, measured the brain composition of 102 people spanning ages 7 to 85 in 24 regions of the brain. The were specifically measuring what’s known as white matter – the fatty protective covering on our nerves that helps them fire more efficiently and, as the name implies, makes up the white part of our brains. People have long known that the white matter increases as the brain matures and white matter abnormalities have been associated with schizophrenia and other conditions. As I wrote in a Stanford News piece:
What [the researchers] found is that the normal curve for brain composition is rainbow-shaped. It starts and ends with roughly the same amount of white matter and peaks between ages 30 and 50. But each of the 24 regions changes a different amount. Some parts of the brain, like those that control movement, are long, flat arcs, staying relatively stable throughout life.
Others, like the areas involved in thinking and learning, are steep arches, maturing dramatically and then falling off quickly. (The group did point out that their samples started at age 7 and a lot of brain development had already occurred.)
That's right. Thinking, learning, emotional control - none of those are firing at full capacity until around age 40. Beyond providing an excuse for a few bad decisions, the work could also become useful for doctors. In this study, the group examined the brains of people with multiple sclerosis, and they were able to detect more subtle decreases in white matter than doctors can when monitoring the disease. The researchers also say the work could help monitor effects of drugs, or diagnose kids who appear to have learning delays.