The Monkey on Your Back or the Bug in Your Brain?
Dealing with addiction is no small feat. Those who are living with addiction face each day fighting the desire to relapse. But why do people become addicted? What happens to make the cravings people feel so hard to ignore? Although not everything is fully understood, the general principles of what happen in the brain of someone addicted to drugs or alcohol can be explained fairly simply.
To begin, when the drug is introduced, the neurotransmitter flow in the natural reward system is disrupted. The neurons recognize the drug as a good experience and the brain tells the body to continue doing whatever action gave the brain this rewarding sensation. The natural reward system primarily works in specific areas of the brain. The ventral tegmental area (VTA) sends dopamine signals to the nucleus accumbens (NAc), which then send signals to make memories about good and bad experiences for future references. Because of this process, dopamine plays a critical role in memory formation. Once the brain forms these memories associating the drug with the intense pleasure, the craving for the drug will be the most prominent when the body is seeking reward in the future.
The dopamine receptors of the NAc have two different types; D1 and D2. When it comes to decision making, D1 receptors lay out all of the options for a typical decision. For instance, it will help recall all of the restaurants you have been to when deciding to do out to eat. D2 receptors help eliminate choices to come to the best decision. In drug addicts, the neural chemistry is imbalanced between the D1 and D2 receptors by having more D1 activity than D2 activity. This means that the D1 receptors are proposing the drug as the easiest possibility to obtain reward and the low activity of the D2 receptors isn’t enough to veto the decision.
Memory is not the only brain function that is affected by drug addiction. The expression of genes also contributes to a person’s development of addiction. When the drug is introduced to the brain, an excess amount of dopamine is released to the neurons. The neurons then respond over time with continued use of the drug by producing more receptors than normal for the excess dopamine. When the individual attempts to quite using the drug, the extra receptors are calling for more dopamine causing withdrawal symptoms, urging the body to find more drugs. The neurons also grow more spines and change their shape to accommodate for the abnormal environment.
Many enzymes and messenger molecules are affected by the excess dopamine, but in general, too much calcium is being pumped into the neuron. Calcium then activates many cell signals such as the gene expression for more receptors and the sensitization to the drug itself.
Unfortunately, treatment for addicts has not quite been pinned down. As we know, rehabilitation and support groups are the main forms of helping individuals recover from addiction. It personally makes me uneasy to think about treating someone with a drug addiction by giving them a different drug to help. It seems like it would be an endless cycle. If a drug could be developed that was not addictive and would fix the neuronal issues, perhaps there will be hope for the future of dealing with addiction!
For more information about the symptoms, risk factors and treatment of addiction, visit the Mayo Clinic’s page about addiction.