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Brains of addicts are inherently abnormal: study

Feb. 3, 2012 - 17:12 By

Drug addicts have inherited abnormalities in some parts of the brain which interfere with impulse control, said a British study published in the United States on Thursday.


  
Previous research has pointed to these differences, but it was unclear if they resulted from the ravages of addiction or if they were there beforehand to predispose a person to drug abuse.

Scientists at the University of Cambridge compared the brains of addicts to their non-addicted siblings as well as to healthy, unrelated volunteers and found that the siblings shared many of the same weaknesses in their brains.

That indicates that the brain vulnerabilities had a family origin, though somehow the siblings of addicts -- either due to environmental factors or other differences in brain structure -- were able to resist addiction.

“Presumably, the siblings must have some other resilience factors that counteract the familial vulnerability to drug dependence,” said the study led by Karen Ersche of the University of Cambridge, published in the journal Science.

“An individual’s predisposition to become addicted to stimulant drugs may be mediated by brain abnormalities linked to impaired self-control.”

Researchers tested 50 biological sibling pairs, in which one was addicted to drugs and the other one had no history of chronic drug abuse. They also tested 50 healthy, unrelated pairs of people as a control group.

The tests involved measuring how well they could control their impulses in a stop-signal reaction time test that assesses how quickly a person can switch from following one set of instructions to another.

Addicts are known to have poor impulse control.

The researchers found that the sibling pairs -- even the non-addicts -- fared significantly worse on the test than the healthy volunteers.

Brain scans showed that the siblings shared some of the same weaknesses in the frontal lobe and its connections to the basal ganglia, which mediates motor, cognition and behavior.

In an accompanying Perspective article, Nora Volkow and Ruben Baler of the US National Institute on Drug Abuse said that knowing more about brain circuitry could help understand and treat other “impaired control” disorders, like obesity, pathological gambling, attention deficit hyperactivity disorder, and obsessive-compulsive disorders.

“Several childhood and adolescent interventions can improve executive function and self-control,” though more study is needed to see how such work may or may not impact the brain, they wrote. (AFP)

 

<한글기사>

마약에 중독되는 성향이 유전된다

마약 중독자들의 뇌에서 발견되는 이상구조가 선천적일 수 있다는 연구결과가 나왔다.

캐런 에르쉐 (Karen Ersche) 박사가 이끄는 캠브리지 대학 연구팀은 지난 2일(현지시각) 개인이 각성제 등에 중독되는 성향은 자기 억제력과 관련되어 있는 뇌 이상에 따라 좌우될 가능성이 있다고 발표했다. 그리고 연구결과에 따르면 이러한 뇌 이상은 중독여부와 관계없이 형제자매간에 동일하게 나타난다는 결과가 밝혀졌다.

연구진은 50명의 중독자와 중독되지 않은 그들의 형제자매를 검사한 뒤, 50명의 건강한 사람들을 검사해 비교해 보았다.

검사과정은 피실험자들이 정지 신호 반응 테스트 (stop-signal reaction time test) 과정에서 얼마나 그들의 충동을 잘 억제할 수 있는지 여부를 알아보는 형식으로 이루어졌다. 정지 신호 반응 테스트는 피실험자가 한 가지 지시를 따르다가 다른 지시를 따르는데 얼마나 시간이 걸리는지 알아보기 위해 시행된다.

그 결과, 중독자들과 그들의 정상적인 혈육들은 건강한 사람들에 비해 충동을 억제하는 능력이 동일하게 확연히 떨어지는 것으로 밝혀졌다. 이들의 뇌를 스캔한 결과 운동능력과 인지력, 태도를 관장하는 부분과 전두엽에서 공통적으로 취약한 부분들이 발견되었다.

같은 결함을 갖고 있음에도 일부는 마약에 중독되지 않는 현상에 대해 연구진은 마약에 의존하게 하는 유전적 취약함에 대항할 만한 다른 요소를 갖춘 것으로 보인다고 발표했다.