Substance addictions

Substance addiction (or dependence on psychoactive substances) is a complex, chronic, relapsing condition characterised by a loss of control over the use of a substance, despite awareness of its negative consequences for health, social, professional or psychological life.

Here are the key elements to understand this concept:

1. The neurobiological mechanism

Addiction is based on the hijacking of the brain’s reward circuit.

• When a person uses an addictive substance (alcohol, tobacco, illicit drugs, certain medications), it triggers a massive release of dopamine in the brain, creating an intense feeling of pleasure or relief.

• With repetition, the brain adapts (the phenomenon of tolerance): it demands higher doses to obtain the same effect, while reducing its ability to feel pleasure from natural everyday activities.

2. The pillars of addiction

To define addiction, experts generally rely on several behavioural criteria:

• The overwhelming urge (craving): An irrepressible desire to use the substance.

• Loss of control: Difficulty limiting use (in quantity or duration) despite the desire to stop.

• Priority given to the substance: Use takes precedence over leisure, social relationships, work or family obligations.

• Continued use despite harm: Continuing to use while aware of the physical (illness), psychological (depression, anxiety) or social problems (isolation, legal/financial issues) it causes.

3. The distinction between use, misuse and dependence

• Simple use: Occasional consumption that does not lead to serious consequences.

• At-risk use: Consumption that increases the likelihood of harm (e.g. drink-driving).

• Addiction (dependence): This is the pathological stage. It often includes a withdrawal syndrome: when the person stops using, they experience painful physical or psychological symptoms (anxiety, tremors, irritability, insomnia), which drives them to use again to make these effects disappear.

4. A multifactorial disease

Addiction does not depend solely on the substance. It results from the interaction between three factors:

1. The substance: Its addictive power (how quickly it changes the brain).

2. The individual: Their genetic vulnerability, personal history, psychological state and background.

3. The environment: Social context, peer pressure, living conditions, stress or past trauma.

In summary, substance addiction is not a lack of willpower, but a brain disease that often requires medical and psychological support to be treated.