Behind the Brain

Drug addiction is a disease that has plagued the world for decades. It causes several personal and economic problems, apart from it’s health concerns. In fact, over 45 million Americans currently deal with drug addiction. And to help cure drug addiction, scientists had to first figure out what the neurobiology of drug addiction is. So what is happening in the brain while addiction develops?

The Brain Reward System

Addiction is the unintentional side effect of our brain’s reward system, a complicated system of intertwined regions that have evolved to reward behavior that helps us survive with dopamine. The main parts of this circuit, so far, include the nucleus accumbens (processes stimuli), the ventral tegmental area (projects dopamine to the nucleus accumbens), and the prefrontal cortex.

Drugs, however, provoke an unnatural release of dopamine in the circuit. This amount of dopamine, is much greater than the amount of dopamine we receive naturally. Therefore, this flood of dopamine not only creates intense pleasure but also teaches the brain to seek drugs at the expense of healthier pursuits.

Neuroplasticity Role in Addiction

Neuroplasticity is the brain’s ability to change and adapt. Hence, it plays an important role in addiction. Repeated use of drugs leads to brain reward circuit neurons undergoing long-lasting changes in structure and function. Some important changes include altered gene expression, altered synaptic connections, and altered neurotransmitter release and receptor sensitivity.

As a result, the brain becomes numb to both the drug and the dopamine. Therefore, the addicted individual continues seeking larger doses of the drug in an attempt to experience the same effect, hence causing further addiction.

Neurotransmitters Involved

While dopamine is considered the main neurotransmitter of addiction, other neurotransmitter systems also make critical contributions:

1. Glutamate: Glutamate is a neurotransmitter that links the environment to drug abuse, thus partially causing relapse
2. GABA: GABA is the major inhibitory neurotransmitter of the brain and contributes to a lack of self-control.
3. Endogenous opioids: These natural pain-relieving neurotransmitters have their functioning modified by opioid drugs, resulting in severe addiction

The Cycle of Addiction

Addiction often progresses through stages, which are temporally defined by specific neurobiological changes. The first stage is called initiation. Typically the first consumption of the drug, initiation consists of elevated dopamine levels, or being “high”. The second phase is withdrawal, in which the addicted individual attempts to stop using the drug. This leads to chemical imbalance in the brain which causes emotional spikes as well as physical symptoms. The last phase is relapse, in which the addicted individual goes back to the drug, due to a variety of reasons including, stress, environment, and depression. Note that not all people in addiction go through all stages. Some go through withdrawal and go clean, while others never may attempt withdrawal.

New Findings and Treatment Options

Over the last few decades, advancements in brain imaging have led to several findings that have revolutionized the understanding of addiction. These findings have shown a volume reduction of gray matter in areas responsible for decision-making along with self-reduced gray matter volume in areas involved in decision-making and self-control. Additional imaging studies also showed that the dopamine activation patterns were altered, and connectivity between brain regions had been changed.

Along with the new understanding of addiction came more modern treatment options. For example, we developed medications that modulated specific neurotransmitters. We also have begun to use behavioral therapy (to strengthen the prefrontal cortex). Lastly, we’ve begun to utilize new technologies such as transcranial magnetic stimulation of neurotransmitter systems, and neurofeedback.

Conclusion

As our understanding of addiction’s neurobiology grows, so does the potential for more effective treatments. Promising areas of research include:

• Personalized medicine approaches based on an individual’s genetic and neurobiological profile
• Novel interventions targeting specific neural circuits
• Strategies to enhance neuroplasticity and promote brain healing

In conclusion, addiction is a complex disorder deeply rooted in the brain’s structure and function. By understanding its neurobiology, we can discover newer treatment approaches, and ultimately help individuals reclaim their lives from the grip of addiction.