How does addiction work?
Addiction is a complex condition that involves significant changes in the brain's structure and function, particularly in the reward and pleasure systems. Here’s a detailed explanation of how addiction works:
The Reward System and Dopamine
The brain's reward system is designed to reinforce behaviors essential for survival, such as eating and reproducing, by releasing the neurotransmitter dopamine. This dopamine release creates a pleasurable sensation, encouraging the repetition of these behaviors135.
Hijacking the Reward System
Addictive substances and behaviors hijack this natural reward system. When an individual uses an addictive substance, such as opioids, cocaine, or nicotine, it triggers a massive surge of dopamine in the brain's reward pathways, often 10 times higher than what is released by natural rewards. This intense dopamine release associates the substance or behavior with an overwhelming sense of pleasure134.
Adaptation and Tolerance
Chronic use of addictive substances leads to adaptations in the brain. The brain reduces its sensitivity to dopamine by decreasing the number of dopamine receptors and releasing less dopamine. This phenomenon, known as tolerance, means that the individual needs increasingly larger doses of the substance to achieve the same level of pleasure. Over time, the brain's reward system becomes less responsive to natural rewards, making everyday activities less pleasurable compared to the addictive substance or behavior135.
Compulsion and Loss of Control
As the brain adapts, the drive to seek the addictive substance or engage in the addictive behavior becomes compulsive. This is not a matter of willpower but rather a biological response. The brain's systems involved in decision-making, memory, and judgment are also affected, leading to drug-seeking behavior driven by habit rather than conscious thought134.
Conditioned Responses and Cravings
The hippocampus and amygdala play roles in storing memories associated with the addictive substance or behavior. These memories create conditioned responses, where environmental cues can trigger intense cravings. For example, seeing a hypodermic needle can trigger a craving in someone addicted to heroin. This conditioned learning explains why relapse can occur even after long periods of abstinence3.
Impact on Brain Function
Addiction affects multiple brain regions beyond the reward system, including those involved in motivation, learning, and memory. It can lead to problems with focus, memory, and decision-making. The overall effect is a shift from conscious, rational decisions to automatic, compulsive behaviors134.
Understanding Addiction as a Disease
Addiction is now recognized as a chronic brain disease rather than a moral failing or lack of willpower. It involves complex biological changes that require comprehensive treatment, often combining medication and counseling to manage the condition effectively135.
In summary, addiction works by hijacking the brain's natural reward system, leading to adaptations that result in tolerance, compulsion, and loss of control, and is driven by biological changes rather than conscious choices.