Research reveals potential cause of youthful impulsiveness

Recent neuroimaging research may have uncovered a neurological pattern explaining the often hasty decisions and rash actions of early adolescence.

In a study using functional magnetic resonance imaging, neuropsychologist Deborah Yurgelun-Todd, PhD, examined the brains of 16 youths, ages 10 to 18, and 18 adults, ages 23 to 32, while showing both groups a picture of a person?s fearful facial expression. (Animal studies associate recognition of fearful emotions with activity in the amygdala, a part of the brain, and Yurgelun-Todd sought to establish if the same is true of human children.)

Adolescents looking at the picture, particularly the younger ones, displayed frenetic brain activity in the amygdala, which is primarily linked with emotions and instinctual reactions. By comparison, the older teen-agers and adults showed the most activity in the more rational frontal lobe?the brain tissue involved in 'planning, insight and organization,' says Yurgelun-Todd.

'The results suggest that adults use a part of the brain that?s better able to process information,' says Yurgelun-Todd, who conducted the study at McClean Hospital in Belmont, Mass., and presented her findings at a symposium on the neurobiology of the psyche at the Massachusetts Institute of Technology.

Based on the findings, Yurgelun-Todd says it?s possible that the frontal lobe only starts maturing at age 17 to 19 and that psychopathology associated with affective illness can set in if a brain abnormality thwarts its growth. She also thinks society can encourage young teen-agers to develop the frontal lobe by teaching them to think rationally.

'The brain is like a muscle in that the more you practice, the better you get,' Yurgelun-Todd says.

?B. Murray