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Addiction as a Disease It seems that wherever one finds intoxication, one likely will find addiction. Recently researchers have argued that the addiction process is like the disease model, with a target organ, a defect, and symptoms of the disease. In other accounts, addiction is a disorder of genes, reward, memory, stress, and choice.

The Disease Model in Addiction

According to the new disease model, rather than being a disease in the conventional sense, addiction is a disease of choice. That is, it is a disorder of the parts of the brain necessary to make proper decisions. As one becomes addicted to cocaine, the ventral tegmentum nucleus accumbens in the brain is the organ. The defect is stress-induced hedonic regulation.

Understanding the impact that genes, reward, memory, stress, and choice have on an individual will begin to explain the Disease Model of Addiction

Genetic

The genetic makeup of an individual determines how they respond to alcohol. What causes an individual to be more prone to addiction is their genetic makeup. For example, there are genetic differences in how people respond to methylphenidate (Ritalin) injections.

Reward

Increased dopamine is correlated with increased pleasure. For that reason, dopamine plays a significant role in reinforcing experiences. It tells the brain the drug is better than expected. When an individual uses a drug, there may be a surge of dopamine in the midbrain, which can result in the shifting of that individual's pleasure “threshold” (see figures one and two).

Memory

The neurochemical, glutamate is the most abundant neurochemical in the brain. It is critical in memory consolidation. When an addict discovers an addicting behavior, glutamate plays a role by creating the drug cues. It is the neurochemical in motivation which initiates the drug seeking, thus creating the addiction.

Stress

When under stress the brain is unable to achieve homeostasis. As a result, the brain reverts to allostasis, which in turn alters the brains ability to process pleasure, which is experienced at the hedonic “set point” (see figures one). Thus, previous pleasures may become no longer pleasurable. This is also known as anhedonia, or “pleasure deafness.” When stressed, the addict may experience extreme craving—an intense, emotional, obsessive experience.

Choice

An addict may incur damage to the orbitofrontal cortex (OFC), the anterior cingulate cortex (ACC), and the prefrontal cortex (PFC). This damage causes a tendency to choose small and immediate rewards over larger but delayed rewards, deficits in social responding due to decreased awareness of social cues, and a failure of executive function such as sensitivity to consequences.