X developing a disorder of the personality of a drug user may have a profound efect on the likelihood of developing substance addiction: defcient ego development with subsequent weak super‑ego control have been seen as responsible for a lack of personal autonomy leading to a behaviour of withdrawing from conficts and seeking surrogate solutions such as drug use; personality disorders, frequently diagnosed in drug‑dependent patients, and a history of abuse in childhood are likely contributors to the development of substance abuse; X other psychiatric co‑morbidity, such as bipolar disorders and schizophrenia, often accompanies drug use and dependency and may have a strong infuence on the development of drug dependency. It is known that mental diseases and substance dependency have the dysfunction of the mesolimbic dopamine system in common; X poor education, social and personal disadvantages, social isolation, unemployment, lack of future prospects and inability to cope with these adverse conditions make (especially young) people susceptible to drug dependency; X the social environment – the culture and what we call the “subculture” of drug users, full of conduct codes and rites – may contribute; X there is growing evidence that genetic factors have a signifcant infuence on the development of substance dependency.6 Hence, drug dependency is a multifactorial disorder resulting from a complex interplay of individual, psychological, social and neurobiological factors that make a person who is exposed to psychoactive drugs susceptible to developing those persistent neurophysiologic alterations in the brain that are responsible for drug dependency and that make abstinence difcult to achieve in a short time. Based on these persistent brain alterations, substance dependency is a chronic disease and, like other chronic diseases such as diabetes and hyper‑ tension, it is characterised by a long course and frequent relapses; it can be treated but rarely cured in the short term. Addiction Addiction is described (rather than defned) as “monopolisation of the atten‑ tion system by addictive stimuli” or “continued compulsive behaviour in spite of the awareness of its adverse health and social consequences”. In contrast, there exist very clear diagnostic criteria for drug dependency. According to 6. WHO: Neuroscience of psychoactive substance use and dependence (Geneva 2004). Prison health care and medical ethics Page 72