Monitor on Psychology - October 2011 - (Page 58)
The danger of
Stimulant drugs damage the brain’s decision-making abilities, revving up the course of addiction and making it harder for people to quit, research suggests.
BY S AD IE F. DI NG FELDER • Monitor staff
timulant drug abuse packs a triple-whammy to people’s decision-making abilities, hampering their reasoning and increasing impulsive and compulsive behaviors, according to research presented at APA’s 2011 Annual Convention by Trevor W. Robbins, a behavioral and clinical neuroscientist at the University of Cambridge in England. These three tendencies all have slightly different origins in the brain, he said, but they all contribute to the story of stimulant drug addiction — clouding people’s judgment during the early stages of addiction, and then making it harder for them to quit. “These drug abusers ... have poisoned their frontal cortex and produced decision-making deficits,” Robbins said. Poor judgment During the early stages of stimulant use, people often make a bad bet — underestimating the number of times they can use cocaine, for example, before becoming dependent. This tendency may be explained in part by the fact that stimulant drug use itself makes people worse gamblers, according to one study by Robbins and his colleagues, published in Neuropsychopharmacology (Vol. 2, No. 4). In the study, the researchers asked four groups of participants — 18 chronic amphetamine users, 13 opiate users, 10 people with orbitofrontal cortex lesions and 10 people with dorsolateral or medial prefrontal cortex lesions — to play a computer game known as the Cambridge Gambling Task. In the game, the computer presents participants with an array of 10 red and blue boxes, and asks them to guess which color box is hiding a yellow square. So, for instance, if the computer
presents participants with six red boxes and four blue ones, a smart participant would bet on the red boxes, since that’s probably where the yellow square is hiding. Then, the computer asks participants to bet a proportion of their points on the correctness of their answer. The stimulant users performed poorly on the task — making decisions slowly and often making the wrong decision. In addition, the longer the participants had been abusing the drug, the worse their decision-making. Opiate users, in comparison, showed slowed performance but generally made the correct bet. Among the participants with brain damage, only the ones with orbitofrontal cortex damage showed a pattern of impaired and slowed decision-making. In a follow-up study, the researchers depleted serotonin levels among healthy participants and found that the participants made poorer decisions, but their decision-making speed was not slowed. “This suggests that, among amphetamine users, their poor decision-making may be associated with orbitofrontal damage and with reduced serotonin function in that region, as methamphetamine addicts have been shown to have reduced signs of serotonin function in the orbitofrontal cortex post mortem,” said Robbins. Flexibility In addition to poor decision-making, stimulant drug use seems to make people less able to adapt when the rules of a game change, according to a study published by Robbins and his colleagues in Nature (Vol. 380, No. 6,569). In a procedure
MONITOR ON PSYCHOLOGY • OCTOBER 2011
Table of Contents for the Digital Edition of Monitor on Psychology - October 2011
Monitor on Psychology - October 2011
Subtle and stunning slights
From the CEO
Live science on the showroom floor
Zimbardo re-examines his landmark study
Ready, set, mentor
Attention students and ECPs: Self-care is an ‘ethical imperative’
Suicide risk is high among war veterans in college, study finds
Psychotherapy is effective and here’s why
From toilet to tap: getting people to drink recycled water
What’s ahead for psychology practice?
A push for more accountability is changing the accreditation process
Peer, parental support prove key to fighting childhood obesity
Popular media’s message to girls
Bullying may contribute to lower test scores
A consequence of cuckoldry: More (and better) sex?
Manatees’ exquisite sense of touch may lead them into dangerous waters
Building a better tomato
How will China’s only children care for their aging parents?
‘Spice’ and ‘K2’: New drugs of abuse now on the market
Many suspects don’t understand their right to remain silent
Boosting minority achievement
Where’s the progress?
And social justice for all
Helping new Americans find their way
Segregation’s ongoing legacy
A new way to combat prejudice
Retraining the biased brain
Suppressing the ‘white bears’
How to eat better — mindlessly
Protect your aging brain
Must babies always breed marital discontent?
The danger of stimulants
Keys to making integrated care work
Is technology ruining our kids?
Facebook: Friend or foe?
The promise of Web 3.0
NIMH invests in IT enhanced interventions
PsycAdvocates work to safeguard key programs
The psychology of spending cuts
APA’s strategic plan goes live
Vote on bylaws amendments
Monitor on Psychology - October 2011