Continued Use After Pathological Problems
The initial response in the VTA continues with downstream long term potentiation in the NAc. This area forms associations with the substances of abuse and creates a link between them and the internal and external social and psychological cues that become associated with the intake of the substances. These cues are the conditioned stimulus that are now indicators of the drugs of abuse (APA, 2015; Flagel et al., 2011; Volkow, Wang, Fowler, Tomasi, & Telang, 2011).
The synapses in the brain react to the intake of the substance and lessen the production of dopamine in those areas after repeated use. When persons who do not take drugs regularly are compared to persons who are abusing substances, we can see that in those persons regularly ingesting drugs, the response to the actual drug begins to produce less of an effect in the dopamine pathways in the VTA. This was the reward for taking the drug in the first place. The response rate is reduced. However in that reduced response the environmental and behavioral cues become much more important (APA, 2015).
From (APA, 2015; Volkow, Wang, Fowler, Tomasi, & Telang, 2011) we learn that the dopamine pathways in the NAc now begin the production of the dopamine in response to cues from the environment. This dopamine response encourages the behavior of taking the drug again (Everitt & Robbins, 2013). The brain was designed for survival. In the case of intake of food or engaging in sex, the initial response of the brain is to produce dopamine to move the individual to seek that biological behavior. In other words, to ensure survival, the brain must make certain that the individual engages in the behavior. The new responses to the environmental cues such as drug paraphernalia, the drug dealer’s house or even the routine in drug use in the NAc create an anticipatory dopaminergic response.
The response to the conditioned stimuli is overwhelming. The dopamine begins the anticipation that there is a reward upcoming which is the drug itself (Flagel et al., 2011). The conditioning from this guarantees that the person with the disorder will procure the drug just as they would procure food for their survival. In a sense these two behaviors are the same. The drugs however have hijacked the same reward systems and even though the drugs are not necessary for survival the strong connections now in place make it seem as if they are necessary (APA, 2015) .
The changes from the use of substances in dopamine systems continues its path through the brain. The substances activate the production of dopamine and also make the pathways less sensitive to the normal survival stimuli such as sex or food. These areas then become less sensitive to the drug itself and also reduce natural production of dopamine. The reduction in dopamine sensitivity and production now complicate matters in the prefrontal cortex (APA, 2015).
This area is known as the executive function center. It is a necessary component to inhibit compulsive behavior. This area helps with self-control, emotion regulation, memory, making decisions and in judgement. A reduction in dopamine in the prefrontal cortex also contributes to the actions of ADHD with regard to response to obsessions and compulsions (APA, 2015; Voeller, 2004). The reduced dopamine in the prefrontal cortex then prevents the person with the substance use disorder from being able to make rational decisions or from enacting self-control mechanisms.
One of the issues with prefrontal cortex inhibition is to create thoughts that are in defense of the disorder through justification and rationalization. The thought patterns that are learned and used as a result of lessened ability to remain rational are considered the psychological basis for substance use disorders. At some point in the 1950’s Albert Ellis theorized that thoughts and perceptions were the driving force behind mental disorders (Patterson, 2015). This theory informs the psychology behind substance use disorder today and is a mainstay in cognitive behavioral therapy.
The idea is that the substance abuser engages in faulty logic, a lens through which the world is viewed. This type of thinking can keep the substance use going because the thinking supports continued use. Some of the thinking patterns might include ideas such as, “I am not hurting anyone,” or “I must take this to feel normal.” These thoughts fit nicely with the idea that those areas of the brain that might normally perform the executive function of decision making and judgment have been compromised.
To further complicate matters, ingesting these substances affects the limbic areas of the brain. The amygdala and hippocampus help in processing emotions and control our reactions to stressful triggers. The brain no longer reacts properly to these triggers. The use of the substance then becomes of paramount importance as a behavior in controlling these emotions. The substance user then begins to think and act in ways that can only make sense in light of an understanding of this disease. Even in the face of the fact that the drug no longer is a pleasure because it does not produce the dopamine that it once did, the person will take it because the alternative, which is to face the stressor without it, is unbearable (APA, 2015).