THE DISEASE MODEL
Addiction is a chronic disease that changes both the structure and function of the brain. The power of addiction arises from the way in which it hijacks parts of the brain that govern behavior and life-sustaining functions—namely, the prefrontal cortex and limbic system. These neurobiological changes, which include atrophy of brain tissue and interference with the brain's reward pathway, become more pronounced over time, reinforcing the addictive and self-destructive behaviors.
The prefrontal cortex is considered the "control center" of the brain. It is responsible for impulse and behavioral control, judgment, planning, decision-making, problem solving, and executive functioning. Chronic opioid use has an inhibitory effect on the cortex, which leads to loss of control over opioid use. The brain's reward center, which is housed in the limbic system, is also implicated in opioid addiction. When the brain's reward center is activated, it triggers the release of dopamine—a chemical in the brain that results in happiness and pleasure.
It's all in your head.
But not how you might think.
There are three distinct aspects of opioid use disorder:
1. Cravings for Opioids
Cravings result from the effect of opioid's on the brain's reward center. Activation of the brain's reward system triggers the release of dopamine—a chemical in the brain that results in feelings of happiness and pleasure. The brain's reward center rewards us for survival activities, like eating, drinking, and having sex. The positive feelings associated with these activities has a positive reinforcing effect and conditions us to repeat them. Unfortunately, the same pathway that rewards survival behaviors also rewards opioid use. When opioids bind to receptors in the brain, it releases excessive amounts of dopamine. The dopamine surge results in intense euphoria, which has a powerful reinforcing effect on the brain. Dopamine is also implicated in memory, and the quick satisfaction and euphoria associated with opioids becomes engrained in one's memory. This conditions the brain to crave opioids, and the brain becomes chemically motivated to seek out opioids. The incentive to seek out opioids for relief or pleasure is commonly referred to as "incentive salience."
2. Loss of Control Over Opioids
Loss of control over opioids results from disruptions in the prefrontal cortex (PFC) and its behavioral control mechanisms. During early stages of opioid addiction, the prefrontal cortex (PFC) sends inhibitory signals to the limbic system to stop releasing dopamine in order to preserve self-control. The limbic system sends a message back to the PFC that opioids are important for survival, which effectively silences the PFC. Because the PFC is responsible for behavioral control, when it is compromised, the individual loses volitional control over opioids. The PFC eventually stops functioning, and the lack of activity causes atrophy (degeneration) in this region of the brain (shown above). Impairment of the PFC leads to total loss of self-control, and the opioid addict eventually becomes incapable of avoiding opioids. This leads to continued opioid use, despite the apparent negative consequences.
3. Continued Opioid Use, Despite Apparent Negative Consequences
Continued opioid use, despite negative consequences, is a manifestation of significant neurochemical changes in both the PFC and the limbic system. The learned association of opioids and euphoria incentivizes opioid use, particularly in response to stress, and motivates the use to seek out opioids regardless of the consequences. Unfortunately, the consequences of opioid use often involve criminalization. Criminalization creates a host of new environmental stressors—namely, social and economic upheaval—which motivates the individual to seek of opioids to provide relief from these new stressors. Criminalization yields a cycle of relapse and re-incarceration, and the increased risk of overdose is renewed with each cycle. Unfortunately, the disease of addiction does not respond to incarceration or punishment, and the desire and will are too powerful to be overcome by these potential deterrents. This is why incarceration is futile. Opioid addiction, like any other chronic and relapsing disease, responds to proper treatment and medication—not judgment and jail time.