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Just bad boys, or malfunctioning brains?

Sept. 26, 2010
Courtesy of the University of Colorado Denver
and World Science staff

An­ti­so­cial boys who abuse drugs, break laws and act reck­lessly aren’t just “bad”: many of them may have mal­func­tion­ing brains, ac­cord­ing to a new stu­dy.

“Brain re­sponses to eve­ry­day re­wards and pun­ish­ments grad­u­ally guide most young­sters’ de­ci­sions to con­form with so­ci­ety’s rules,” said Thom­as Crow­ley, a psy­chi­a­trist at the Uni­vers­ity of Col­o­rad­o School of Med­i­cine and lead­er of the stu­dy.

A brain area known as the dor­so­lat­er­al pre­fron­tal cor­tex is as­socia­ted with de­ci­sion­mak­ing, after re­ceiv­ing in­for­ma­tion about re­wards and pun­ish­ments from an inner part of the brain. (Im­age cour­tesy US Nat'l Cen­ter for Bio­tech­nol­ogy Info/NIH)


But “when these se­ri­ously trou­bled kids ex­pe­ri­ence re­wards and pun­ish­ments… their brains ap­par­ently mal­func­tion,” he added. “Our find­ings strongly sug­gest that brain mal­func­tion un­der­lies their fre­quent fail­ure to con­form to rules, to make wise de­ci­sions, and to avoid re­lapses back to drug use and an­ti­so­cial acts.”

The sci­en­tists, from the Uni­vers­ity of Col­o­rad­o at Boul­der and the Uni­vers­ity of Mar­y­land, stud­ied 20 ad­o­les­cent boys who on av­er­age had been on proba­t­ion 139 of the pre­v­ious 180 days. 

Nine­teen of the 20 had the psy­chi­at­ric di­ag­no­sis of con­duct dis­or­der, and all had di­ag­noses of sub­stance use dis­or­der. They had been ab­sti­nent, how­ev­er, an av­er­age of about five weeks when stud­ied. They were com­pared with 20 oth­er boys who did not have se­ri­ous an­ti­so­cial or drug prob­lems, but who were of si­m­i­lar age, eth­nicity, and home neigh­bor­hoods.

All were asked to play a com­pu­ter­ized risk-taking game that re­peat­edly pre­sented a choice be­tween a cau­tious and a risky be­hav­ior: press the left but­ton and al­ways win one cent, or press the right but­ton and ei­ther win five cents or lose ten cents. 

In­ter­est­ing­ly, the sci­en­tists said, the num­ber of risky right presses was si­m­i­lar in the two groups. This might have oc­curred, they added, be­cause the game forced the boys to de­lib­er­ate for sev­er­al sec­onds be­fore press­ing ei­ther but­ton.

Yet there were dra­mat­ic dif­fer­ences in brain ac­ti­vity be­tween the two groups of play­ers, the re­search­ers not­ed. They ex­am­ined which parts of the brain were most ac­tive dur­ing play us­ing a scan­ning tech­nol­o­gy known as func­tion­al mag­net­ic res­o­nance im­ag­ing. 

Nor­mal­ly, a brain re­gion called the the an­te­ri­or cin­gu­late cor­tex mon­i­tors chang­ing re­wards and pun­ish­ments, and then sends that in­forma­t­ion to anoth­er brain re­gion, the dor­so­lat­er­al pre­fron­tal cor­tex, which reg­u­lates one’s choices among pos­si­ble be­hav­iors. 

Dur­ing decision-making, an­ti­so­cial boys had sig­nif­i­cantly less brain ac­ti­vity than nor­mals in both of those re­gions, and al­so in oth­er decision-making ar­eas, the in­ves­ti­ga­tors found. On the oth­er hand, there were no parts of the brain in which the an­ti­so­cial young­sters showed more ac­tiva­t­ion.

As pre­dicted by oth­ers not as­so­ci­at­ed with the stu­dy, the an­ti­so­cial boys al­so had dys­pho­ria, a chron­ic sad-anxious state, the re­search­ers said. They also di­splayed “re­ward in­sen­si­ti­vity”; in the game their brains showed less res­ponse than the com­par­i­son boys’ brains to wins. They add­it­ional­ly were found to have “pun­ish­ment hy­per­sen­si­vi­ty,” with great­er brain re­sponse to losses than com­par­i­son boys.

The study was pub­lished Sept. 22 on­line in the re­search jour­nal PLoS One.


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Antisocial boys who abuse drugs, break laws and act recklessly aren’t just “bad”: many of them may have malfunctioning brains, according to a new study. “Brain responses to everyday rewards and punishments gradually guide most youngsters’ decisions to conform with society’s rules,” said Thomas Crowley, a psychiatrist at the University of Colorado School of Medicine and leader of the study. But “when these seriously troubled kids experience rewards and punishments… their brains apparently malfunction,” he added. “Our findings strongly suggest that brain malfunction underlies their frequent failure to conform to rules, to make wise decisions, and to avoid relapses back to drug use and antisocial acts.” The scientists, including collaborators at the University of Colorado at Boulder and the University of Maryland, studied 20 adolescent boys. On average they had been on probation 139 of the last 180 days; 19 of the 20 had the psychiatric diagnosis of conduct disorder, and all had diagnoses of substance use disorder. They had been abstinent, however, an average of about five weeks when studied. They were compared with 20 other boys who did not have serious antisocial or drug problems, but who were of similar age, ethnicity, and home neighborhoods. All were asked to play a computerized risk-taking game that repeatedly presented a choice between a cautious and a risky behavior: press the left button and always win one cent, or press the right button and either win five cents or lose ten cents. Interestingly, the scientists said, the number of risky right presses was similar in the two groups. This might have occurred, they added, because the game forced the boys to deliberate for several seconds before pressing either button. Yet there were dramatic differences in brain activity between the two groups of players, the researchers noted. They examined which parts of the brain were mostactive using a scanning technology known as functional magnetic resonance imaging. Normally, a brain region called the the anterior cingulate cortex monitors changing rewards and punishments, and then sends that information to another brain region, the dorsolateral prefrontal cortex, which regulates one’s choices among possible behaviors. During decision-making, antisocial boys had significantly less brain activity than normals in both of those regions, and also in other decision-making areas, the investigators found. On the other hand, there were no parts of the brain were the antisocial youngsters showed more activation. As predicted by others not associated with the study, the antisocial boys also had dysphoria, a chronic sad-anxious state, with “reward insensitivity”; in the game their brains responded less than the comparison boys’ brains to wins. They also had “punishment hypersensitivity”, with greater brain response to losses than comparison boys.