Decision-Making Functions of the Brain Central to Drug Addiction
Drug addiction is developed through a combination of biological and environmental factors. Each patient with an addiction represents a unique combination of factors that led to the condition. However, even if two individuals have identical environments, it does not guarantee that both individuals will have identical outcomes with addiction development.
A new study helps to explain why some individuals are able to use drugs, but do not develop an addiction. It also helps to explain why some patients are able to resist cravings after completing a substance abuse treatment program, while others experience relapse.
The study, conducted by researchers at the RIKEN Center for Molecular Imaging Science, located in Japan, and the Montreal Neurological Institute at McGill University in Canada, provides new information about brain circuitry that controls decision-making. The study finds that addiction may be linked to abnormal functions in the frontal cortex, the area that is responsible for decision-making.
The study’s findings are published in a recent issue of the journal Proceedings of the National Academy of Sciences of the USA. They show that the orbital and lateral regions of the brain, located in the frontal cortex, work together when cue related to drugs or craving is introduced. When those two areas of the brain do not work together well, addiction may be the result.
To examine this function of the brain, the researchers used a combination of tools, uniting functional magnetic resonance imaging (fMRI) with transcranial magnetic stimulation (TMS). The participants included 10 smokers, who were evaluated for cue-induced cravings and the resulting neural mechanisms. The researchers based this examination not only on cravings, but how the brain responds when drugs are not available, despite a craving.
The researchers found that among smokers the orbitofrontal cortex (OFC) was key in monitoring the level of craving and the dorsolateral prefrontal cortex (DPFC) evaluated drug cues and availability of the drug. The study demonstrated that the DPFC was able to suppress functions in the OFC if the cigarette was not available to the individual.
The study also tested the results of the DPFC being non-active using TMS and found that cravings and the related signals occurring in the OFC were not related to drug availability.
With these findings, the researchers conclude that the DPFC is central to functions of drug cues and evaluating drug availability and then works with the OFC where the information from the DPFC is used to determine whether drug-seeking behaviors will follow.
The authors of the study explain that in their smoker participants, after evaluating the drug cues and availability status in the DFPC, the cravings accumulated in the OFC. The authors found the results interesting, given that the neural circuits involved are central to decision-making and self-control, but normally guide an individual to making the most beneficial decision.
There are many research studies out there trying to understand drug addiction. Read Drug Addiction ‘Turned Off’ With Lasers to see another take on addiction recovery.