Usage may start as a weekly thing. Just a party on the weekend. This phase of the disease may last for a while. Friends are using, everyone's having fun, and the drug makes you feel better. This allows the situation to slip into everyday usage which moves the person into the third stage, abuse.
Consequences become a factor.
Friends may drop out of school, lose jobs, or develop legal problems. From the abuse stage to the fourth and final phase - dependency. All of these factors revolve around other complex social, emotional, and cultural factors. One important question is the drug itself. Drugs such as heroin and crack cocaine are so incredibly powerful that their effects on the chemistry of the brain are devastating.