ABSTRACT
The randomized controlled trial (RCT) is revered by researchers and has become the gold standard by which treatments are assessed. The application of the RCT to psychotherapy research is deceptively simple. A homogeneous group of patients with a specific problem are allocated randomly to different treatments. The acceptability of the Medical Research Council statement may depend on careful definition of a complex intervention. The research field lacks a reliable instrument for measuring structural changes in personality functioning as a result of psychotherapeutic intervention. Offering them referral into a research project in which their allocation appears to be dependent on the toss of a coin confronts them with loss of control and threatens tenuous stability. The guiding principle of mentalization-based treatment is that psychotherapy with borderline patients should focus on the capacity for mentalization, by which is meant the implicit or explicit perception or interpretation of the actions of others or oneself as intentional—mediated by mental states or mental processes.
