Chronic and excessive drinking is associated with structural, physiological, and functional changes in multiple regions of the human brain, including the prefrontal cortex, the medial temporal lobe (MTL), as well as structures of the brain's reward system. This study of the ability of alcohol-dependent (AD) individuals to learn new reward-related contingencies and then transfer this knowledge to new contexts found the AD patients had transfer deficits.
Results will be published in the June 2012 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"AD individuals often have problems applying the knowledge they acquire during psychotherapy to later prevention of drinking relapses in real life," said Martina Rustemeier, a research associate in the department of neuropsychology at Ruhr University Bochum in Germany as well as corresponding author for the study. "For example, even though AD individuals become quite aware of the negative consequences of drinking such as family problems, as well as the positive consequences of not drinking, they still have difficulties permanently changing their behavior when they are back to their normal lives."
Rustemeier explained that AD patients are taught skills during hospitalization and/or psychotherapy that will help them to cope with daily life problems and difficulties for when they are back at home. They are expected to learn, transfer and apply their coping mechanisms to "life" situations such as dealing with stressful work problems that might have previously caused them to drink. But this "transfer of knowledge" is not always successful.
"By disentangling learning from a positive feedback such as monetary reward, and learning from negative feedback such as no monetary reward," said Rustemeier, "we wanted to examine how AD individuals learn and if they benefit more from positive or negative reinforcers, which could in turn help to find successful reinforcers and therapy methods for AD patients."
Boris Suchan, a professor in the department of neuropsychology at Ruhr University Bochum applauded this study for showing a differentiated pattern of learning deficits in alcoholics. "It is not a zero-one result," he said, "showing that there is a decline in the ability to acquire new information. The results show clearly that context-related processing of newly acquired contents is impaired in AD patients."
Rustemeier and her colleagues gave 24 recently detoxified AD patients (19 men, 5 women) and 20 healthy controls (11 men, 9 women) a feedback-learning task associated with monetary rewards. Learning performance, transfer performance, the individual learning bias (i.e. better learning from positive or negative feedback), and associations among learning variables and alcohol and nicotine consumption patterns, depression, and personality traits were all examined.
Both Rustemeier and Suchan noted that while the AD patients did not show a general learning deficit or problems acquiring new information, the patients clearly had difficulties transferring their acquired knowledge into a new context.
"Deficits in transfer of knowledge to new contexts as shown by AD patients is typically seen in declarative learning impairments," said Rustemeier. "Declarative learning, in turn, is associated with the MTL. However, the behavioral results of our investigation do not allow firm conclusions about dysfunction of the MTL region of the brain in our patient group.
"These findings have profound implication for therapeutic interventions," said Suchan, "as AD patients should be prepared in advance for such situations. AD individuals as well as family members should know that every new situation is a new challenge for which they cannot rely automatically on previously acquired information in a flexible way. Maybe this makes it easier to understand at least in part the behavior of AD patients."
Rustemeier agreed. "Clinicians and therapists should consider this finding during therapy because it can explain why AD individuals have problems applying learned techniques to prevent drinking relapse outside the clinical setting," she said. "They have difficulties in permanently changing their behavior. Therefore, to prevent drinking relapses, adequate and successful reinforcers are necessary. In our study, patients showed good learning with monetary rewards, but it is quite possible that transfer would be more successful with other reinforcers."
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