10 parts of the brain affected by addiction

The 10 key parts of the brain affected by addiction are the basal ganglia, extended amygdala, prefrontal cortex, brain stem, hippocampus, ventral tegmental area (VTA), nucleus accumbens, orbitofrontal cortex, Insula and anterior cingulate cortex as expounded by The Surgeon General’s Report on Alcohol, Drugs, and Health: Facing Addiction in America (2016):

1. Prefrontal Cortex

The prefrontal cortex is critical for decision-making, impulse control, and planning. Addiction impairs this area, leading to poor judgment and difficulty controlling urges. Studies shown by the National Institute on Drug Abuse (2022) in their Drugs and the Brain article state that chronic substance use reduces the volume and functionality of the prefrontal cortex, which exacerbates compulsive drug-seeking behavior and makes it difficult for individuals to evaluate long-term consequences​.

2. Nucleus Accumbens

The nucleus accumbens plays a central role in the brain’s reward circuitry. It is heavily involved in the release of dopamine, the neurotransmitter associated with pleasure and reinforcement. Addiction hijacks this system, causing the nucleus accumbens to become hypersensitive to drug-related cues while diminishing response to natural rewards​.

3. Amygdala

The amygdala is essential for emotional processing and the stress response. In addition, it becomes hyperactive, heightening anxiety and stress reactivity, which increases cravings and the risk of relapse as individuals seek substances to alleviate negative emotions. According to Roberto M’s 2021 study, ‘The Role of the Central Amygdala in Alcohol Dependence,’ the central amygdala (CeA) is composed mainly of GABAergic neurons and influences addiction by modulating emotional responses and interacting with reward pathways.

4. Hippocampus

The hippocampus is vital for memory formation and learning, and its role is particularly significant in the context of addiction. Addiction disrupts the hippocampus’s ability to create new memories and retrieve existing ones, especially those related to drug use. This impairment contributes to persistent and intrusive drug-related memories that trigger cravings and increase the risk of relapse.
According to Takashima, Y., & Mandyam, C. D’s 2018 study, ‘The role of hippocampal adult neurogenesis in methamphetamine addiction’, chronic use of addictive substances, such as methamphetamine, can lead to impaired hippocampal function, which is linked to a higher likelihood of relapse, with approximately 40% to 60% of individuals with addiction experiencing at least one relapse episode after recovery.

5. Ventral Tegmental Area (VTA)

The ventral tegmental area (VTA) is a key part of the brain’s dopamine system. It sends dopamine signals to various brain regions, including the nucleus accumbens and prefrontal cortex. Addiction enhances the activity of the VTA, leading to excessive dopamine release and reinforcing drugs’ rewarding effects​​.

6. Hypothalamus

The hypothalamus regulates numerous bodily functions, including stress response, hunger, and thirst. Addiction disrupts the hypothalamus, leading to hormonal imbalances and alterations in stress response. This disruption affects the hypothalamic-pituitary-adrenal (HPA) axis, contributing to the physical and psychological symptoms of addiction and withdrawal​.

7. Insula

The insula is involved in interoception, or the awareness of internal body states. According to Naqvi, N. H., & Bechara, A.’s, 2008, study titled, “The hidden island of addiction: the insula. Trends in neurosciences”, functional imaging studies have shown that activity within the insula is correlated with subjects’ ratings of drug urges.
The insula becomes hyperactive, increasing sensitivity to drug-related cues and physical cravings. This heightened interoceptive awareness reinforces the compulsion to seek and consume substances despite negative consequences. Notably, smokers with brain damage involving the insula are more than 100 times more likely to quit smoking easily and immediately without relapse, highlighting the crucial role of the insula in addiction.

8. Basal Ganglia

The basal ganglia are critical for habit formation and motor control. Addiction alters the functioning of the basal ganglia, leading to the development of compulsive habits and automatic drug-seeking behaviors. These changes make it difficult for individuals to break free from the cycle of addiction even when they consciously want to stop​​.

9. Anterior Cingulate Cortex

The anterior cingulate cortex (ACC) is involved in emotional regulation, decision-making, and error detection. Addiction impairs the ACC, reducing its ability to monitor and control behavior. This impairment contributes to the inability to recognize the negative consequences of drug use and to regulate emotions effectively​.

10. Orbitofrontal Cortex

The orbitofrontal cortex (OFC) is crucial for evaluating rewards and making value-based decisions. The OFC becomes dysfunctional, leading to an overvaluation of drug-related rewards and an undervaluation of natural rewards. This imbalance drives the persistent pursuit of drugs over healthier life choices​

What Role Does the Dorsal Striatum Play in The Development of Addiction?

The dorsal striatum plays a crucial role in the development of addiction by facilitating habit formation and procedural learning. Repeated drug use reinforces neural pathways in the dorsal striatum, transforming voluntary drug use into compulsive habits that become difficult to break.

How Does the Periaqueductal Gray (pag) Contribute to Addiction?

The periaqueductal gray (PAG) contributes to addiction by modulating pain and the body’s stress response. The periaqueductal gray (PAG) plays a key role in opioid effects, as opioids interact with the PAG to produce pain relief and euphoria. Chronic opioid use alters PAG functioning, leading to increased tolerance and dependence.

What Is the Function of The Thalamus in Addiction?

The function of the thalamus in addiction is to act as a relay station for sensory and motor signals to the cerebral cortex. It processes drug-related cues and environmental triggers. This region integrates sensory experiences with the reward system, making certain cues more likely to trigger cravings and relapse.

How Does the Locus Coeruleus (lc) Impact Addiction, Particularly Opioid Addiction?

The locus coeruleus (LC) impacts opioid addiction by regulating arousal and stress through norepinephrine production. Chronic opioid use suppresses LC activity, leading to tolerance. During withdrawal, the LC becomes hyperactive, causing anxiety, agitation, and insomnia.

What Is the Significance of The Bed Nucleus of The Stria Terminalis (bnst) in Addiction?

The significance of the bed nucleus of the stria terminalis (BNST) in addiction lies in its involvement in the extended stress and anxiety response. The BNST plays a critical role in mediating the stress-related aspects of drug craving and relapse. It integrates stress signals and amplifies the emotional reactions that drive drug-seeking behavior.

How Does the Caudate Nucleus Contribute to Addiction?

The caudate nucleus contributes to addiction by being a crucial part of the brain’s learning and memory system, especially in goal-directed behaviors. Alterations in the caudate nucleus intensify the focus on drug-seeking behaviors, reinforcing the association between drug use and perceived rewards.

What Role Does the Substantia Nigra Play in Addiction?

The substantia nigra plays a critical role in addiction by being involved in movement and reward through the production of dopamine. Substances that boost dopamine levels affect the substantia nigra, enhancing the rewarding effects of drugs and perpetuating the cycle of addiction through reinforced drug-seeking behaviors.

How Does the Raphe Nuclei Influence Addiction?

The raphe nuclei influence addiction by modulating serotonin, a neurotransmitter that affects mood, anxiety, and sleep. Altered serotonin levels in the raphe nuclei impact mood and emotional states, spawning the psychological aspects of addiction and affecting an individual’s susceptibility to relapse.

What Is the Role of The Parietal Cortex in Addiction?

The role of the parietal cortex in addiction involves processing sensory information and being crucial for spatial awareness and attention. Changes in the parietal cortex influence how individuals perceive and respond to drug-related cues, enhancing their salience and increasing the likelihood of craving and relapse.