Editors' ChoiceImpulse Control

The Brain Says Go!

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Science Translational Medicine  09 May 2012:
Vol. 4, Issue 133, pp. 133ec81
DOI: 10.1126/scitranslmed.3004255

As a group, teens are more likely than others to take risks and engage in impulsive behaviors, activities that—perhaps to the disbelief of some parents—might have developmental benefits. Of course, risky, impulsive behaviors can also be dangerous; a classic example is experimentation with recreational drugs, which can lead to abuse and dependence. To understand better the causes of such behaviors, which might in turn have benefits for adolescent health, Whelan et al. sought to determine the brain networks and other factors involved in inhibitory control in young teenagers.

These researchers used functional magnetic resonance imaging to visualize brain activity in nearly 2000 14-year-old adolescents as they performed “stop-signal tasks.” (In this technique, the time required to stop a motor response that has already been initiated is used as a measure of impulse control.) Whelan and colleagues also gathered data about drug use, symptoms of attention deficit with hyperactivity disorder (ADHD), and genetics, investigating variations in genes related to the function of norepinephrine and dopamine (substances previously shown to act in inhibitory control). Statistical analysis revealed that decreased activity of a network in the orbitofrontal cortical region—an area of the brain implicated in impulse control—was associated with drug use in early adolescence. Additionally, activity in the right inferior frontal region was related to the speed of the inhibition process and the use of illegal substances; it was also associated with a particular variant of the norepinephrine transporter gene.

This study indicates that there are distinct neural networks involved in impulse control in teenagers. The work is limited by a cross-sectional design that did not permit direct testing of the temporal relation between network anomalies and the development of substance abuse and other disorders of impulse control. Future studies should address this issue through longitudinal evaluations of network measures in patients with ADHD and substance abuse syndromes, and in individuals at risk for these and other impulse disorders. Despite this limitation, the hope is that research of this kind might advance knowledge about the biological underpinnings of impulsivity and the potential effects of early interventions targeted to ameliorate early risk factors such as ADHD.

R. Whelan et al., Adolescent impulsivity phenotypes characterized by distinct brain networks. Nat. Neurosci. 29 April 2012 (10.1038/nn.3092). [Abstract]

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