Christopher F. Fear

Probabilistic reasoning in obsessive-compulsive and delusional disorders

BACKGROUNDnDelusional disorder (DD) and obsessive-compulsive disorder (OCD) have been investigated in previous studies using probabilistic reasoning paradigms and abnormalities in each group have been reported. No study to date has compared results between these groups. This study compares patients with these disorders with those who have both phenomena.nnnMETHODSnThirty subjects with DD, 29 with OCD and 16 with obsessive and delusional features were compared with 30 normal controls in a study of probabilistic reasoning using two different computer-based tasks involving a Bayesian paradigm.nnnRESULTSnDeluded subjects showed a jump to conclusions reasoning style, but on a test that added a consequence to their choices did not differ from normals. OCD subjects deviated from Bayesian and control norms to a greater degree than did DD subjects. In subjects with mixed psychopathology, the presence of both phenomena appeared to normalize these probability estimates.nnnCONCLUSIONSnOur findings extend those of others but require cautious interpretation as to the role of probabilistic reasoning in the genesis of delusions or obsessions. Obsessionals in both the OCD and Mixed groups, showed substantial deviation from Bayesian norms, suggesting that obsessionality leads to a reasoning style that is less normal than that of delusionals. Further work is required to investigate clinical correlates of these findings which provide modest support for the proposal that the combination of obsessions and delusions confers greater functional advantages than simply having delusions or obsessions.

Attributional style and delusions: an investigation based on delusional content

Individuals with persecutory delusions have been reported to make external and stable attributions for negative events and to have a tendency towards internal attributions for positive events. It remains unclear whether this abnormality is present in individuals with non-persecutory delusions. Using the Attributional Style Questionnaire, we assessed the attributional style of 19 individuals with persecutory or grandiose delusions (PG), 12 individuals whose delusional beliefs were non-persecutory and non-grandiose (NPG) and 24 controls. The PG group displayed externality in their causal attributions for bad events but those in the NPG group did not differ from controls. Both deluded groups were significantly more stable in their attributions for bad events in comparison to controls. Such findings argue against a primary role for attributional biases in the genesis of delusions, although a role in shaping delusional content and maintaining the disorder and a role for external attributions in defending against reductions in self-esteem cannot be excluded.

Delusional phenomenology--dimensions of change.

Although the application of cognitive techniques to both the measurement and modification of delusional beliefs has recently been developed in more theoretical detail (e.g. Chadwick & Lowe, 1994, Behaviour Research and Therapy, 32, 355-367) there has not been an effort to examine the variability of delusional phenomenology across time. In the present study we report on the treatment of 6 individuals who fulfilled DSM-III-R (American Psychiatric Association, 1987) criteria for Delusional Disorder and who received cognitive therapy targeted specifically on the single symptom of their delusional belief(s). Single-case time-series methodology was used to examine the associations between different aspects of delusional phenomenology through baseline and intervention study phases. Belief maintenance factors were found to be significantly associated with conviction in all 3 individuals who responded to the intervention. Negative behaviours, affect associated with the belief, preparedness to talk to others about the belief and insight were associated with conviction in some individuals but not others. Preoccupation and acting on the belief were aspects of delusional phenomenology that were found to systematically vary independent of belief conviction. The results support a multidimensional view of delusional phenomenology and the process of change during cognitive intervention.

Obsessive-Compulsive Disorder with Delusions

Obsessive-compulsive (OCD) and delusional disorders (DD) have been recognised with increased frequency in recent years, and the propensity of some OCD subjects to become deluded has become a focus of interest. This study reports illness-specific demography along with measures of symptom severity and tests to assess schizotypal ideation, dysfunctional attitudes, attributional and attention bias in 30 patients with OCD, 29 with DD, 16 with OCD with delusions (OC-DD) and a 30-subject control group (CG). Obsessional features appeared before delusions in the OC-DD group, suggesting that OCD was the primary pathology. Delusions were more likely in subjects obsessional about one rather than multiple themes. There was some support for proposals that depression and schizotypy may bring out delusions in OCD and some evidence for the utility of categorising OCD according to the number of obsessions a subject has.

Symptoms or side effects? Methodological hazards and therapeutic principles

The case is described of a 40 year old man with delusions and hallucinations, who at the start of this study was taking doses of neuroleptic medication greatly in excess of those that have been demonstrated to be optimally effective. Over 48 weeks, using PQ methods and detailed interviewing, his progress was charted as the medication was reduced to more appropriate levels. Across this change, his delusional beliefs remained unchanged, but there were substantial reductions in auditory hallucinations, as well as in hopelessness and anxiety. The case has implications for concepts of therapy in the psychoses and for the methodology of therapy studies. It also illustrates possible benefits of using PQ or other self‐assessment methods as a means of calibrating therapy and perhaps enhancing compliance.