For this study, we chose to categorise drug and alcohol use as treated and untreated drug use rather than as problem and recreational drug use. This is because the question of whether or not drug use is a problem for an individual is a subjective question which can only be properly answered by the individual, their family or close contacts, whereas the question of whether drug use is treated or untreated is an objective measurement. The term recreational drug use tends to de-emphasise the seriousness of the behaviour. It should be noted that individuals often underestimate the harm to themselves and rarely perceive the harm to the community which results from such behaviours.