Objectives: There has been a resurgence of interest in the view that persecutory delusions serve a function of defending self-esteem. An alternative account of levels of self-esteem in individuals with persecutory delusions is that they result from processes similar to those studied in people with depression (i.e. from the occurrence of a range of life experiences and how the individual interprets and copes with them). This study aimed to examine both hypotheses together for the first time, and, as the literature indicates that delusions may not share a common cause, attention was given to the possibility of the presence of subgroups.
Design: Data were examined cross-sectionally and longitudinally from a randomized controlled trial of cognitive behaviour therapy for 60 people with drug-resistant psychosis.
Method: The study is based on the initial assessment of all participants on self-esteem, delusional conviction and a large number of demographic, clinical and cognitive measures. Longitudinal analyses were also carried out, and are reported separately for those who received the therapy intervention and those in the control group.
Results: Almost three-quarters of participants with persecutory delusions reported low self-esteem. Changes over time in total self-esteem correlated with changes in measures of mood and social functioning, but not conviction in persecutory delusions. The individuals who initially had normal levels of self-esteem displayed a different pattern of results from the majority of participants.
Conclusion: Low self-esteem in people with drug-resistant persecutory delusions is common and, in most cases, can best be understood in terms of normal emotional processes. There was evidence that the majority of persecutory delusions do not fit either strong or weak formulations of the delusion-as-defence explanation and that there may be subgroups with differing aetiologies. These results need to be replicated, and extended to groups in which symptoms are not resistant to medication.