Left Hemispheric "Imbalance" in Drug Addiction

Drug addiction is a chronic brain disease that leads to functional and structural changes in the brain and an alteration of the function of specific regions, such as the neural circuits of the limbic system (reward related), and the prefrontal cortex delegated to higher cognitive functions (planning and motivational behavior). Moreover, the dorsolateral prefrontal cortex (DLPFC), which is part of a more complex network of brain areas, including the orbitofrontal cortex and the nucleus accumbens, is thought to underlie decision-making processes and to be impaired in substance use disorder patients. Indeed, the DLPFC may show an interhemispheric imbalance with increasing of the left hemisphere cortical activity, attributable to reward-related processes induced by reward bias in addiction. We considered the main theoretical models that try to explain the transition between casual substance use to addiction behavior, and we propose the "Cortical Imbalance Model," which may have significant implications for treatments by modulating the DLPFC: indeed, brain stimulation might improve both clinical phenomenology and metacognitive strategies in addiction.