One of the main obstacles to the diagnosis and treatment of co-morbidity is the fact that psychiatric staff generally have little knowledge of drug treatment and drug treatment staff generally know little about psychiatry. The paradigms of the two specialties are quite different: one is based on the disciplines of medical and science, the other on psychosocial methods and theories. Additionally, the philosophy of mental health services is usually concerned principally with preserving the safety of individuals and the public, whereas addiction services expect clients to be motivated, to some degree, to attend treatment. These different points of departure often prevent a global, integrated perception.
As discussed above, both psychiatric teams and substance services regularly fail to identify significant numbers of patients with co-morbidity. When patients with dual diagnosis seek treatment, their acute psychiatric syndromes are often mistaken for substance-induced symptoms or, conversely, withdrawal or intoxication phenomena are misinterpreted as psychiatric illness. Too often, mental health workers are inclined to send people with co-morbidity to addiction care and workers in addiction care promptly send them back – or vice versa. Continuity of care is impossible under such circumstances. Even when co-morbidity is diagnosed, it is often considered no further in the subsequent treatment interventions (Krausz et al., 1999). The same is true of patients diagnosed with substance use problems in psychiatric care, who normally do not receive any substance-related interventions (Weaver et al., 2003). These generalisations do not, of course, exclude the fact that some psychiatric and drug services achieve very good results with patients with co-morbidity.
In addition, when identified, drug users are often met with suspicion in psychiatric services, and may be refused admission, as may happen to users who are stable on substitution treatment. Similarly, clients may be excluded from drug treatment because of their mental problems. In Spain, for example, most psychiatric services exclude clients with substance disorders and their staff members have no appropriate training. A survey among Austrian psychotherapists revealed that only some are willing to admit drug-addicted patients as clients (Springer, 2003). From Italy it is reported that there are no clear rules for the referral of clients from drug treatment services to mental health services and that there is resistance in mental health services because of lack of expertise. In Norway, referral from low-threshold drug services to psychiatric treatment is reported to be difficult.
In Greece, 54 % of drug treatment programmes do not admit drug users with psychiatric disorders. In drug-free residential treatment in Slovenia, and also in other countries, treatment programmes require patients to be drug-free as a condition for admission. In the case of dual diagnosis patients, this presents a serious obstacle, as complete abstinence would require the termination of other treatments, which is not always possible.