[Drug compliance and health locus of control in schizophrenia]

Schizophrenia is a frequent disorder since it affects about 1% of the general population. Drug compliance, that is to say patients' adherence to their treatment, remains rather poor concerning this disease with, on an average, one patient out of two not complying with his/her medication. Among the factors influencing drug compliance, we focused on patients' beliefs in terms of health control, a concept known as health locus of control. This is a concept that originated from social psychology and derived from the Rotters' original concept of locus of control: it corresponds to the type of connexion established by an individual between subsequent events in the history of his/her disease and internal (personal abilities) or external factors (chance, powerful others). Nowadays, the tridimensional structure of this concept is commonly admitted as being in three dimensions: internality, chance externality and powerful others externality, the latter group being divided between doctors and others. We have assumed that there is a correlation between the degree of drug compliance and the internal and/or doctors' external health locus of control. For this purpose, we have determined the quality of drug compliance by using the Medical Adherence Rating Scale (MARS) and the type of health locus of control by using the Multidimensional Health Locus of Control (MHLC) scale among 65 schizophrenic patients. We have also considered it was important to evaluate patients' insight by using the Amador's scale (Scale of Unawareness of Mental Disorder) because many researchers have established a strong correlation between insight and drug compliance in schizophrenia. Associations between the four dimensions of health locus of control ("internal", "chance external", "others external" and "doctors' external") and drug compliance were assessed by estimating Spearman's rank correlation coefficient (r) and its degree of significance (p). These associations were judged significant at an alpha threshold of 5%, which corresponded to a level of p inferior to 0.05. Our results tend to confirm a statistically significant positive correlation between internal (r=0.25; p=0.043) and/or doctors' external (r=0.27; p=0.027) health locus of control and drug compliance. Conversely, there is no correlation between chance external or others' external health locus of control and drug compliance (p>0.05). This means that the more patients believe that their schizophrenia can be controlled by themselves and/or by doctors, the more they follow their prescriptions. Furthermore, the link between health locus of control and drug compliance appears to be confused by two dimensions of insight, namely awareness of the response to the treatment and perceived need for treatment. An application of these results is that, in the case of patients whose health locus of control is chance or others' external, it can be beneficial to attempt to change their beliefs in order to improve drug compliance. These results hold particular interest in the field of psycho-education and can be directly applied to cognitive therapy for beliefs among stabilized schizophrenic patients.