Addiction is a complex disease that affects brain function, and there is substantial evidence that it is related to loss of frontal lobe function and increased impulsivity. The part of the brain that causes addiction is called the mesolimbic dopamine pathway, or the brain reward circuit. The prefrontal cortex acts as a brake on the brain, sending signals to inhibit particular behaviors or actions. When addiction damages this area of the brain, it also limits the brain's ability to control other behavioral systems.
Studies have demonstrated lower glucose metabolism throughout the brain, including the frontal cortex, during cocaine, morphine, or alcohol poisoning. In contrast, marijuana poisoning is associated with higher levels of glucose metabolism in the prefrontal cortex, orbitofrontal cortex, and striatum in marijuana users. Similarly, faster metabolism in the prefrontal cortex, the anterior cingula, the orbitofrontal cortex, and the striatum has been reported in cocaine users after sequential intravenous administration of methylphenidate. We conceptualize drug addiction as a syndrome of altered response inhibition and attribution of salience and called it the “I-RISA syndrome” of drug addiction.
This syndrome is characterized by impaired functioning of the prefrontal cortex (PFC), which is responsible for decision-making and impulse control. Damage to this area of the brain can further interfere with the functioning of other brain regions associated with addictive problems such as reward system, memory and emotions, and stress regulation centers. It is important to understand how addiction affects the prefrontal cortex in order to develop effective treatments for addiction. Neuroimaging studies have shown that drug administration can lead to changes in functional measures such as glucose metabolism and cerebral blood flow (CBF).
Additionally, functional connectivity studies have revealed patterns that predict disease severity and treatment outcomes. In conclusion, addiction is a complex disease that affects multiple areas of the brain, including the prefrontal cortex. Damage to this area of the brain can lead to impaired decision-making and impulse control, which can further interfere with other brain regions associated with addictive problems. Additionally, functional connectivity studies have revealed patterns that predict disease severity and treatment outcomes.