Adolescence, defined as the transition period between puberty and adulthood, is characterized by major changes in psychological, emotional, and social processes and is often associated with challenging behaviors. Adolescents may be moody, defiant, and engage in substance use and other risky behaviors. It is at this stage of life that people are most vulnerable to developing mental health problems such as schizophrenia.
According to neuroscientific theory, adolescence is characterized by the gradual maturation of executive functions and the development of higher-order cognitive skills, such as decision-making and planning, with which we coordinate other cognitive abilities and behaviors. But at what point in adolescence is this maturation process complete?
A new “big data” study shows precisely when executive function matures. The results, published in the journal Natural communicationsdemarcate the boundary between adolescence and adulthood, to reveal when adolescents begin to think like adults.
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Studies of executive function development typically examine how processes such as working memory, inhibitory control, and task switching change with age, but most use either small numbers of children and adolescents performing a wide range of these tasks, i.e. a large number performing only one task. little. Brenden Trevo-Clemmens of the University of Minnesota and colleagues pooled the results of four large independent studies to create a dataset including the performance of nearly 10,800 individuals aged 8 to 35 on 23 different measures of function. executive from 17 distinct tasks. They were thus able to trace the maturation of executive functions throughout adolescence.
Analysis of the data revealed that performance on almost all tasks improved with age, with the greatest improvements occurring between early and mid-adolescence (ages 10 to 15), and improvements more modest but nevertheless significant between mid and late adolescence (15 to 18 years). years). Performance on all measures stabilized at adult levels between 18 and 20 years old.
The authors say their findings support and provide rare direct evidence for the idea that adolescence is a distinct transitional phase during which goal-directed executive functioning reaches maturity.
The brain continues to change
Executive function depends largely on a brain structure called the prefrontal cortex (PFC), which undergoes prolonged maturation during adolescence. Numerous brain imaging studies, however, show that PFC maturation continues into the third decade of life, much later than the maturation of executive function observed here.
“The PFC is clearly relevant to executive function, and brain processes and cognitive performance can be used to delineate the boundaries of adolescence,” says Tervo-Clemmens. “Our work focuses on behaviors defined by computerized cognitive tasks, and we have not measured the brain processes themselves.”
“One idea we have is that brain maturation in the 20s may be important for fine-tuning day-to-day or context-to-context variability, which is not well captured by assessments computerized cognitive techniques in the laboratory,” he adds.
“Similarly, we believe that cognitive graphs and brain changes are only part of the puzzle when determining when adolescents reach adulthood, and should be used alongside emotional responses and sociocultural frameworks to discuss and consider the limits of adolescence. »
Tervo-Clemmens says he and his colleagues plan to study the issue in contexts closer to the real world, assessing executive function in participants’ daily lives using, for example, smartphone apps, rather than relying solely on laboratory tasks.
“This will help us better understand multiple sources of variability, both within and between individuals, and get closer to real-world results,” he says. “We also plan to continue to develop this knowledge to illuminate the emergence of mental health symptoms, which typically first appear in adolescence, and which may be associated with executive function. »