BIOCHEMISTRY OF ADDICTION

Neurotransmitters like dopamine, serotonin, and norepinephrine play a central role. Dopamine, in particular, is associated with pleasure and reward and is often elevated during substance use, reinforcing addictive behaviors. 

The brain's reward pathway, primarily involving the mesolimbic dopamine system, is heavily implicated. Drugs and certain behaviors can overstimulate this pathway, leading to addiction.

Over time, the brain adapts to the presence of substances by reducing the response to neurotransmitters, leading to tolerance. This often results in increased substance use to achieve the desired effect.

When the substance is removed, withdrawal symptoms occur. These are often the opposite of the drug's effects and can be highly unpleasant, driving continued use.

The brain's ability to rewire itself is crucial. Addiction can lead to changes in neural pathways, making it harder to quit and increasing cravings.

Genetic factors can influence an individual's susceptibility to addiction. Certain genes may affect how a person responds to drugs or experiences cravings. 

Stress and underlying mental health issues can contribute to addiction. Substance use often becomes a coping mechanism to alleviate stress or mental health symptoms.

Environmental factors, such as access to substances, peer influence, and trauma, can contribute to addiction risk.

Changes in gene expression due to environmental factors can also impact addiction susceptibility.

Chronic drug use can lead to neuroinflammation, which can further alter brain function and contribute to addiction.