I’m Sorry

Addiction fundamentally alters the brain’s reward and decision-making systems through well-documented neurobiological mechanisms. When substances like drugs (including alcohol and nicotine) are consumed, they trigger massive releases of dopamine in the brain’s reward circuit, particularly in areas like the nucleus accumbens and ventral tegmental area. With repeated exposure, the brain adapts by reducing natural dopamine production and decreasing the number of dopamine receptors, creating tolerance and requiring increasingly larger amounts of the substance to achieve the same effect. This neuroadaptation hijacks the brain’s natural reward system, making everyday activities less rewarding while the addictive substance becomes disproportionately important.

Over time, addiction also impairs the prefrontal cortex, the brain region responsible for executive functions like decision-making, impulse control, and weighing long-term consequences. This creates a neurological double-bind: the midbrain structures driving craving and drug-seeking behaviour become hyperactive, while the prefrontal systems that would normally regulate these impulses become weakened. Chronic substance use also disrupts stress response systems, making individuals more vulnerable to relapse during difficult periods. These changes help explain why addiction is recognised as a chronic brain disease rather than simply a matter of willpower – the neuroplastic changes can persist long after substance use stops, though the brain does have remarkable capacity for recovery with sustained abstinence and appropriate treatment.

The Challenge of Stopping

The challenge of stopping stems from the profound neurobiological changes addiction creates in the brain’s fundamental survival systems. The brain essentially learns to treat the addictive substance as necessary for survival, similar to food or water. When someone tries to quit, they face intense physical withdrawal symptoms as their neurochemistry struggles to return to homeostasis, combined with psychological cravings that can persist for months or years. The damaged prefrontal cortex makes it extremely difficult to override these powerful urges with rational decision-making, while stress, environmental cues, and emotional states can trigger automatic drug-seeking responses that feel almost involuntary. This creates a cycle where attempts to quit often lead to temporary success followed by relapse, which many interpret as personal failure rather than recognising it as part of the neurological reality of the condition.

Addiction appears progressive because tolerance drives escalating use over time, while the brain’s reward system becomes increasingly dysregulated. What begins as recreational use gradually shifts to compulsive use as natural dopamine production diminishes and neural pathways become more deeply entrenched. The condition typically follows a predictable pattern: initial experimentation leads to regular use, then to use despite negative consequences, and finally to compulsive use where the person continues despite severe impairment in major life areas. Additionally, chronic substance use often damages the brain regions responsible for insight and self-awareness, making it harder for individuals to recognise the severity of their condition. The progressive nature is also influenced by external factors – as addiction advances, people often lose social supports, employment, and housing, creating additional stressors that fuel continued use and make recovery more challenging.

Understanding addiction when you’re not “addicted” to alcohol or other drugs

The difficulty in understanding addiction, even among people with their own compulsive behaviors, stems from several key differences in how these conditions manifest and are perceived. While behaviors like sugar consumption, social media use, or shopping can indeed activate similar dopamine pathways, they typically don’t create the same level of neurobiological hijacking that occurs with substances like alcohol, opioids, or stimulants. Addictive drugs often produce dopamine surges 2-10 times greater than natural rewards, creating more profound and lasting changes to brain structure and function. Additionally, many behavioral compulsions allow people to maintain relatively normal functioning in major life areas, whereas substance addiction typically leads to progressive deterioration across multiple domains – relationships, work, health, and legal standing.

The social and cognitive factors also create barriers to understanding. Most people can relate to losing control occasionally – eating too much dessert or spending too much time scrolling their phone – but these experiences usually involve temporary lapses that can be corrected relatively easily through willpower or environmental changes. This creates a false sense of equivalency where people think “I can stop eating cookies when I want to, so why can’t they just stop drinking?” They don’t grasp that addiction involves a qualitatively different level of brain change where the substance has become neurobiologically essential, not just psychologically preferred. There’s also often a moral lens applied to addiction that doesn’t exist for other compulsive behaviours – society tends to view overconsumption of legal, socially acceptable things as personal quirks or minor character flaws, while addiction to illegal substances or excessive alcohol use carries heavy stigma and assumptions about moral failing, making it harder to see as a medical condition requiring treatment rather than simply better self-control.

A Word On Nicotine (Tobacco Products)

Yes, nicotine absolutely does release large amounts of dopamine, making it highly addictive despite being legal and socially accepted in many contexts. Nicotine causes an increase in dopamine levels in the brain’s reward pathways, creating feelings of satisfaction and pleasure.Research shows that nicotine, like opioids and cocaine, can cause dopamine to flood the reward pathway up to 10 times more than natural rewards.

This helps explain why nicotine addiction can be so powerful and difficult to overcome, even though people often view smoking or vaping as less serious than other forms of substance addiction. Repeated activation of dopamine neurons in the ventral tegmental area by nicotine leads not only to reinforcement but also to craving and lack of self-control over intake. The addiction develops through the same basic mechanisms as other substances – as people continue to smoke, the number of nicotine receptors in the brain increases, requiring more of the substance to achieve the same dopamine response.

What makes nicotine particularly insidious is its legal status and social acceptance, which can make people underestimate its addictive potential. The rapid delivery of nicotine to the brain (within 10-20 seconds when smoked) creates an almost immediate reward that strongly reinforces the behaviour. This is why many people who successfully quit other substances still struggle with nicotine, and why nicotine addiction often serves as a gateway that primes the brain’s reward system for addiction to other substances.

Dr Rangan Chatterjee chats with Dr Gabor Maté about his radical findings based on decades of work with patients. We’re currently living in a culture that doesn’t meet our human needs. Maté and Chatterjee delve into how our emotional stress can translate into physical chronic illnesses, and how loneliness and a lack of meaningful connection are on the rise, as are the rates of autoimmune disease and addiction.

To answer that question, I’ll need to explain a part of the brain called the Limbic System.

Within the brain there is a set of structures called the limbic system. There are several important structures within the limbic system: the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus. The limbic system is among the oldest parts of the brain in evolutionary terms. It’s not just found in humans and other mammals, but also fish, amphibians, and reptiles.

The limbic system is the part of the brain involved in our behavioural and emotional responses, especially when it comes to behaviours we need for survival: feeding, reproduction and caring for our young, and fight or flight responses (https://qbi.uq.edu.au/brain/brain-anatomy/limbic-system).

The limbic system contains the brain’s reward circuit or pathway. The reward circuit links together several brain structures that control and regulate our ability to feel pleasure (or “reward”). The sensation of pleasure or reward motivates us to repeat behaviours. When the reward circuit is activated, each individual neuron (nerve cell) in the circuit relays electrical and chemical signals.

In a healthy world without addictive manufactured drugs, humans survive and thrive when they are rewarded for certain behaviours (cleaning, hard work, sex, eating, achieving goals etc), hence evolution has provided us with this feel-good chemical so that we will repeat pleasurable behaviours.

There is a gap between neurons called the synapse. Neurons communicate with each other by sending an electro-chemical signal from one neuron (pre-synaptic neuron) to the next (post-synaptic neuron). In the reward circuit, neurons release several neurotransmitters (chemical messengers). One of these is called dopamine. Released dopamine molecules travel across the synapse and link up with proteins called dopamine receptors on the surface of the post-synaptic neuron (the receiving nerve cell). When the dopamine binds to the dopamine receptor, it causes proteins attached to the interior part of the post-synaptic neuron to carry the signal onward within the cell. Some dopamine will re-enter the pre-synaptic nerve cell via dopamine transporters, and it can be re-released.

When a reward is encountered, the pre-synaptic nerve cell (neuron) releases a large amount of dopamine in a rapid burst. Dopamine transporters will remove “excessive” amounts of dopamine naturally within the limbic system. Dopamine surges like this help the brain to learn and adapt to a complex social and physical world.

Drugs like methamphetamine (a stimulant drug) are able to “hijack” this process contributing to behaviours which can be considered unnatural or potentially dysfunctional. A range of consequences can follow.

When someone uses methamphetamine, the drug quickly enters the brain, depending on how the drug is administered. Nevertheless, meth or ice is quick acting. Meth blocks the re-entry of dopamine back into the pre-synaptic neuron – which is not what happens naturally. This is also what cocaine does to the brain. However, unlike cocaine, higher doses of meth increase the release of dopamine from the presynaptic neuron leading to a significantly greater amount of dopamine within the synapse. Higher doses of cocaine will not release “more dopamine” from the pre-synaptic neuron like meth does. This is why after about 30 minutes or so, people who use cocaine will need more to maintain the high.

Dopamine gets trapped in the synapse (space between nerve cells) because the meth (like cocaine) prevents “transporters” from removing it back into the cell it came from. The postsynaptic cell is activated to dangerously high levels as it absorbs so much dopamine over a long period of time. The person using meth experiences powerful feelings of euphoria, increased energy, wakefulness, physical activity, and a decreased appetite.

When an unnatural amount of dopamine floods the limbic system like this over a long period of time, without reabsorption, then our brain is not replenished with dopamine, hence people who use meth often (even on a single occasion) may feel unmotivated, depressed, joyless, and/or pointlessness when they stop using. Figuratively speaking, the brain is “empty” or low on dopamine fuel, and it will take time to for dopamine to return to baseline levels and replenish itself. This may motivate the user to seek more methamphetamine to return to “normal”.

Methamphetamine can also cause a variety of cardiovascular problems, including rapid heart rate, irregular heartbeat, and increased blood pressure. Hyperthermia (elevated body temperature) and convulsions may occur with methamphetamine overdose, and if not treated immediately, can result in death (What are the immediate (short-term) effects of methamphetamine misuse? | National Institute on Drug Abuse (NIDA) (nih.gov))

SIGNS OF SUBSTANCE MISUSE OR ADDICTION

• Finding it difficult to meet responsibilities.
• Withdrawing from activities or not enjoying activities that used to provide satisfaction e.g. work, family, hobbies, sports, socialising.
• Taking part in more dangerous or risky behaviours e.g., drink driving, unprotected sex, using dirty needles, criminal behaviour.
• Behaviour changes e.g., stealing, exhibiting violence behaviour toward others.
• Conflict with partner/family/friends, losing friends.
• Experiencing signs of depression, anxiety, paranoia, or psychosis.
• Needing more substance to experience the same effects
• Cravings and urges to use the substance and symptoms of withdrawal when not using the substance.
• Having difficulty reducing or stopping substance use.
• Regretting behaviours while under the influence and continuing to use again.

(Substance abuse, misuse and addiction | Lifeline Australia | 13 11 14)