Substance abuse, also known as drug abuse, is a patterned use of a substance (drug) in which the user consumes the substance in amounts or with methods which are harmful to themselves or others. The exact cause of substance abuse is impossible to know because there is not just one direct cause. However substance abuse and addiction is known to run in families. One theory suggests there is a genetic disposition which predisposes certain individuals toward substance abuse. Another suggests substance abuse is learned there for people subjected to substance abuse by those around them begin to copy the same behaviors. Substance abuse might start out as a bad habit but when and if addiction develops it manifests as a chronic debilitating disease. (Full article...)