The form of the drug habit envisions dependence as a end result of a course of action in which various items combine to direct drug-using behavior and the deficiency of adaptability regarding the will to use a particular drug. Even though the effects of a given drug are important, it would be foolish to assume that everyone who is addicted to the same drug goes through similar experiences or has similar motivations. Also, different elements may carry different weights during the various stages of development of drug addiction.

Three factors are important In the beginning. These include if the drug is easily accessible, if its accepted socially and whether the person is surrounded by friends who are using it.

There are 7 billion souls on the planet, each of which has a different personality and biological make-up. This means that everyone experiences a given drug differently and the way the brain responds to repeated drug use is different in every body. The pharmacological properties of the drug being used is vital. This may mean the difference between using and being addicted, whether the drug will cause side effects, and how successfully one can recover from the addiction.

According to many scientists,the difference between voluntary drug use and compulsive addiction boils down to alterations in the anatomy and biochemistry of the drug addict. Scientific data is accumulating steadily which confirms this belief. Alas, it remains unknown if these changes are mandatory and ample to explain the addictive habits. Others argue against such a simplistic model. They say that the resourcefulness of drug addicts to change their addictive conduct in reply to rewards or punishments shows that the form of addiction is complicated requiring interplay of diverse ingredients.

These can include pressing social and psychological circumstances in addition to distant events which happened in the past.

Drug use starts a chain reaction which can either reward or punish and which can be learned resulting in high or low probability that the drug using actions will be repeated. The consumption of some drugs also starts the biological actions affiliated with tolerance, addictions and sensitization. Subsequently, tolerance (larger doses required to achieve the same effect) decreases some of the negative effects the drug. This in turn allows the use of greater doses, which can precipitate the progression to physical dependence. Avoiding the very unpleasant withdrawal associated with most of the addicting drugs then becomes a driving force promoting more drug use. Increased (sensitized) drug craving when environmental stimuli associated with drug taking, or drug cues, are encountered. This increases the risk of relapse in addicts attempting to quit.