The drugs quickly activate the brain's reward system - a primitive neurological circuit buried beneath the cortex - and release dopamine. This neurotransmitter, which is central to pleasure and desire, sends a message to the brain: This is an important experience worth remembering. Through this, the body begins to ask for the sensation released by dopamine, causing the body to become addicted to the substance.
Alcohol, for example, acts on the nervous system by changing behavior and may even lead to addiction. Its consumption initially promotes disinhibition, relaxation and euphoria. In a second moment the depressing effects begin to appear, such as speech and reasoning difficulties, slow reflexes, worsening of motor coordination and behavioral alteration. A laughing alcoholic may suddenly turn into a violent subject. These combined effects can cause a large number of problems, such as domestic violence and traffic accidents, many of them with death or permanent disability.
