An estimated 25% to 50% of patients with schizophrenia experience residual symptoms, including medication-resistant delusions.1,2 These persistent symptoms contribute to the chronic, debilitating course of the illness. Delusions are defined as “fixed false beliefs” that have the following attributes3:
• Certainty: held with absolute conviction
• Incorrigibility: not changeable by compelling counterargument or proof to the contrary
• Impossibility or falsity of content: implausible, bizarre, or patently untrue convictions
In addition, a delusional belief is generally not shared by other members of a person’s culture or community.4
According to this definition, delusional patients would not be expected to express doubt about their delusional beliefs. However, recent research suggests that delusions in fact are multidimensional and that they vary over time in degree of conviction, distress, preoccupation, action, insight, and interference with daily functioning.5-7Some of the factors thought to contribute to the origin of delusions and maintenance of delusional conviction are belief inflexibility and a “jumping to conclusions” bias.5,8-17
Studies have shown that cognitive-behavioral therapy (CBT) reduces acute and medication-resistant psychotic symptoms, including delusional beliefs.18-26 In this setting, CBT aims to enlist the patient in a collaborative investigation of evidence for and against his or her beliefs, using the A-B-C model, where:
• A is an event (such as a “voice”)
• B is a belief about the meaning of A (the voices are omnipotent and must be obeyed)
• C is the emotional and behavioral consequence of this belief (fear and social isolation)
In psychosis, A and B are often fused in the patient’s mind.
The clinician attempts to separate event from belief about event by gently kindling doubt about the delusions and therefore decreasing the patient’s belief inflexibility. Garety and colleagues27 found that among patients who received CBT, the ability to acknowledge “the possibility of being mistaken” about their delusional beliefs was a strong predictor of success of therapy. In a small study of cognitive therapy for delusions, Sharp and colleagues8 found that changes in items of the Maudsley Assessment of Delusions Schedule (MADS), a scale that measures conviction in delusions, correlated with therapeutic improvement. More recent evidence suggests that women with schizophrenia and a low level of conviction in their delusions are most likely to respond to brief CBT.9
While CBT for psychosis attempts to increase the patient’s doubts about his delusional beliefs during treatment, little is known about preexist-ing doubts that patients may harbor before receiving CBT. In a study we undertook at the State University of New York Medical Center, the goal was to examine doubts patients might have about their delusions before their beliefs were challenged with CBT. More specifically, the study aimed to determine (1) the feasibility of measuring doubt about delusions in a single cross-sectional interview; (2) the reasons patients doubted their delusions; and (3) the correlation between degrees of doubt and conviction with other dimensions of psychosis.
We hypothesized that some degree of doubt may be present before delusions are challenged in treatment and that this doubt may be elicited in a single semistructured interview when the interviewer uses an open, nonconfrontational approach. We predicted that patients might report both conviction and doubt simultaneously, and that low levels of doubt would correlate with higher scores on measures of severity of psychotic illness.