The bio-psychosocial or BPS approach to treatment of drug abuse is often defined in opposition to reductionist models. Reductionist models tend to assume a single cause for medical conditions and addictions. The most common reductionist model is a purely biological one which assumes that the singular cause of a problem such as addiction is biomedical and thus that the problem can be solved by medication alone. The BPS model takes a more holistic approach, assuming that while biology is a contributing factor, individual psychology and social situation are equally important. For instance, taking a teen drug addict who was the victim of child abuse and is living in a single parent home, in a neighbourhood filled with gangs, and just giving him medication to help with drug or mental health problems without counselling or changes to external environment, is, according to the BPS model and empirical studies, ineffective. Instead, all three contributing causes must be addressed.