Introduction
Delusions are a cardinal feature of psychotic illness, present in around three quarters of people with a schizophrenia spectrum diagnosis [
1,
2]. Religious themes are common across delusion categories and types, with between a fifth and two-thirds of all delusions reflecting religious content [
3‐
6]. To be classified as a religious delusion, the belief must be idiosyncratic, rather than accepted within a particular culture or subculture [
7]. Strongly held beliefs that are shared within an existing religious or spiritual context would not, therefore, be considered to be religious delusions, irrespective of co-occurring psychosis. For example, believing oneself to be able to hear the voice of Jesus is not uncommon in a Christian society and thus would not in itself be classified as a religious delusion. In contrast, believing oneself to be inhabited by the warring spirits of multiple interspatial deities, would be considered to be a religious delusion. Culturally acceptable religious beliefs are cited as an important coping strategy for many people with schizophrenia, and may contribute to lower symptom severity in both severe and enduring mental illnesses [
8,
9] and common mental disorders [
10,
11]. Religious delusions, in contrast, have routinely been linked to poorer prognosis for people with psychotic disorders [
12].
Levels of disability, distress and conviction have all been reported to be higher in people with religious delusions compared to other types of delusions [
1,
3,
4,
13‐
15]. Religious delusions are also associated with poor engagement, low satisfaction with services and with treatment, and longer duration of untreated psychosis [
12,
16‐
19]. People with religious delusions appear, therefore, to be a particularly problematic group to treat effectively, and ought to be targeted for psychological therapies [
20,
21]. However, as the mechanisms underlying the treatment resistance are poorly understood, further study is required to establish what the particular foci of psychological intervention for people with religious delusions should be, and what issues are likely to arise in implementation.
Cognitive models of psychosis [
22,
23] identify specific psychological maintaining factors for delusions. Prominent amongst these are persisting anomalous experiences, reasoning biases, affective processes, and poor adjustment to psychosis resulting from personal beliefs about illness, treatment and recovery. Religious delusions can be plausibly linked to increased difficulty in all these areas.
Anomalous experiences These may be perceived as having religious significance (e.g., communications from higher powers) and thus be specifically attended to, engaged with and even deliberately induced. Frequent anomalous experiences provide repeated evidence to sustain the delusion.
Reasoning biases Delusions are considered to arise from, and be maintained by, biases and errors in evidence-based reasoning. These include ‘jumping to conclusions’ (JTC) by making decisions based on limited data, and belief inflexibility, comprising difficulty adjusting beliefs in response to contradictory evidence; difficulty considering the possibility of being mistaken; and difficulty identifying plausible alternative explanations [
24]. Faith, by its nature, relies on foundations other than a systematic and evolving evidence base, and religious or spiritual insights tend to be based on revelation, dramatic events or inner conviction, rather than a process of hypothesis testing. It is also common, and, in some religions, even desirable, for religious beliefs to be held with high conviction, certainty of rectitude (rather than possibility of being mistaken), and without alternatives. Should these features of religious beliefs equally characterise delusions with religious content, reasoning biases may be particularly prominent, and thus contribute to severity, persistence, and higher levels of conviction.
Affective disturbance Affective processes are implicated in the onset and maintenance of delusions by their impact on attentional, perceptual, interpretative and memory processes, and through maladaptive coping and affect regulation strategies [
25]. Religious delusions, by definition, concern themes of universal existential import, and are therefore likely to be particularly associated with strong affect, with consequent cognitive-perceptual and behavioural changes which may act to further increase delusion severity [
26].
Beliefs about illness, treatment and recovery How a person makes sense of the changes associated with psychosis is important to their adjustment and to their engagement with treatment [
27,
28]. Religious delusions may be particularly likely to involve a rationale at odds with the tradition of Western psychiatric empiricism that characterises mental health services in the UK. This mismatch of explanatory models may underpin the association of religious delusions with poor engagement with treatment and with services [
28,
29].
Aims of the current study
We set out to compare a large sample of people with religious delusions to people with other kinds of delusions to identify the psychological factors which may contribute to the increased persistence, disability and distress reported to be associated with religious delusions. All participants had current delusional symptomatology, and a schizophrenia spectrum diagnosis verified by trained assessors. The aim was to develop a better psychological understanding of religious delusions to inform model development and, thereby, intervention.
We tested the following specific hypotheses:
1.
In line with previous studies, people with religious delusions will have higher levels of symptomatology and delusional conviction, and poorer engagement in treatment than people with other kinds of delusions.
2.
People with religious delusions will have more anomalous experiences, more negative affect and more reasoning biases than people with other kinds of delusions.
3.
People with religious delusions will have less insight and more unhelpful attitudes towards their treatment than people with other kinds of delusions.
Discussion
We set out to examine the psychological correlates of the higher levels of persistence, distress and disability reported in the literature to be associated with religious delusions. Our aim was to understand the perceptual, emotional, cognitive, and behavioural processes underlying the treatment resistance, to better inform cognitive behavioural interventions.
In this large sample, around a fifth of delusions was religious in content. We found that religious delusions were associated with higher levels of positive symptoms, auditory and other hallucinations, thought disorder, bizarre behaviour and passivity phenomena. People with religious delusions also reported more internal evidence for their delusions (anomalous experiences or mood changes), and were very likely to have an accompanying grandiose delusion. In contrast to findings in the literature [
1,
3,
4,
13‐
19], they had lower levels of negative symptoms, with no differences in their degree of delusional conviction or in the likelihood of them engaging in treatment. Levels of affective disturbance were similar in RD compared to other delusions, and reasoning biases were, if anything, less pronounced in the religious delusions group, as people with religious delusions were more likely to be able to identify an alternative to their delusion. The groups did not differ in their levels of insight, engagement or in their beliefs about treatment.
It is possible that by selecting participants for the current study who were already to some degree treatment resistant (history of relapse, or of symptom persistence), some of the differences found between those with religious delusions and those with other delusions in studies based on unselected samples were minimised. Nevertheless, our findings suggest that levels of positive symptoms, and specifically of grandiosity and anomalous experiences, including passivity phenomena, are elevated in people with religious delusions, even when compared to an otherwise similarly ‘unwell’ group. These characteristics could plausibly underlie the persistence of religious delusions and their resistance to treatment. There was no evidence that any other hypothesised maintaining factor was differentially elevated, or that beliefs about treatment were more negative in the religious delusions group. This is surprising as grandiose beliefs were prominent in the group, and are characterised by a greater likelihood of reasoning biases [
47]. As with accompanying persecutory delusions in Garety and colleagues’ study, it is possible that accompanying religious delusions act to moderate the cognitive and affective biases that are characteristic of grandiose delusions. The religious delusions group overall was no more likely to experience paranoid delusions than the group with no religious delusions.
Greater grandiosity may in itself be a block to treatment [
1]; in that professionals may be hesitant to intervene because of the apparently protective effects of the delusion, or because of low levels of distress. Nevertheless, despite the co-occurrence with grandiosity, our findings suggest that beliefs about treatment and engagement are no different in people with religious delusions, compared to any other delusion, and, therefore, that a range of interventions should be offered. Indeed, the greater likelihood of generating an alternative to the beliefs raises the possibility that people with religious delusions may be particularly amenable to cognitive behavioural therapy. There was no evidence from our sample to suggest that this, or any other treatment offered, would be particularly unacceptable to a religious delusions group.
Considering the severity of psychotic symptomatology amongst religiously deluded patients, they may also benefit from being offered a review of their medication. Despite experiencing positive symptoms to a greater degree, medication levels, measured by CPZ equivalents, were no different in the religious delusions group compared to people with other kinds of delusions, and over 60 % were on a ‘low’ or ‘medium’ dose of medication. This is a crude index, and may simply represent avoidance of over-prescribing, but as the group did not demonstrate poor insight, or negative attitudes to medication, the possibility of improving outcomes by optimising pharmacological interventions should also be considered, and may act synergistically with psychological therapy.
Clinical implications
We found that religious delusions were more likely to be accompanied by grandiose delusions, and high levels of positive symptomatology, including hallucinations, passivity phenomena, and unusual behaviour. Within a cognitive model of religious delusions, persistence of distress and disability and poorer outcomes may, therefore, be driven by high levels of ongoing evidence for the delusion in the form of anomalous experiences. It is possible, if the experiences have religious significance, that the person engages in particular behaviours to bring these experiences on. The high levels of bizarre behaviour found in our sample would be consistent with this suggestion. Bizarre behaviour may also act to alienate the person and reduce opportunities for social support and potential disconfirmation through social contact; or form a safety behaviour, preventing testing out of concerns [
48,
49]. Odd behaviours may also act directly to confirm delusions by generating unusual or adverse reactions from others. High levels of grandiosity may limit the person’s ability to reflect upon, and consider, both their actions, and their explanations of experiences. Grandiose delusions may have positive implications which mean the person is reluctant to change them.
Our findings suggest that in therapy with people with religious delusions, particular emphasis should be placed on the nature of ongoing evidence. Alternative explanations for this are likely to be available, but care may be required to ensure that valued and potentially self-esteem enhancing aspects of the belief, and those associated with positive religious coping [
50,
51], are not modified in an unhelpful way, and that interventions are genuinely collaborative and carefully targeted on distress and disability. Attentional processes are also likely to be an important target, aiming to reduce unhelpful tendencies to look out for, and to focus on, anomalous experiences. Some negotiation, and discussion of pros and cons, may be required around behaviours which are causing difficulty or placing the person at risk, if their negative impact is not recognised by the service user. The role of particular behaviours in triggering or maintaining anomalous experiences, or reducing the possibility of disconfirmation should be considered.
Limitations
This study adopted a cross sectional design and thus no causal relationships can be established. Cultural factors were not a focus of either main study, so despite their importance to RD, they could not be considered in this investigation. Multiple tests were carried out, and, although the sample size is large, only the global positive symptom, delusion and bizarre behaviour differences remain significant after Bonferroni correction. The findings should, therefore, be taken as pointers for future research, which should specifically target participants with RD to recruit in sufficiently large numbers.
Future research
Clarification of possible cultural variations in the psychological mechanisms underpinning religious delusions would be a useful area for future research. Researchers have proposed a distinction between African-Caribbean patients and other ethnic groups in their religious activity and belief levels [
52], and the incidence of psychosis is itself influenced by racial and cultural characteristics [
53]. Testable predictions arise from the tentative cognitive model of religious delusions proposed. Further research is required to clarify levels of engagement with and appraisals of anomalous experiences in people with religious delusions, and the impact of experiences and appraisals on behaviour. More work is needed to understand the difference between socially acceptable religious beliefs and religious delusions, particularly the factors determining the helpfulness or otherwise of a belief [
54].
Conclusions
Approximately one-fifth of people with delusions have religious delusions. Their attitudes to and levels of engagement with treatment are similar to those of people with any kind of delusion, and therefore efforts should be made to optimise both psychological therapies and prescribing. Cognitive therapy may be an especially good ‘fit’, with adaptations to specifically target high levels of positive symptoms, particularly anomalous and passivity experiences, and their impact on behaviour, in the context of grandiosity. A cognitive model of religious delusions needs to incorporate an understanding of the differential impact of religious belief compared to religious delusion, and the role of anomalous experiences. Such experiences may be valued, rather than distressing, and care should be taken to understand and to preserve life-enhancing aspects of beliefs, to promote a personally meaningful recovery.
Acknowledgments
The PRP group work was supported by a programme Grant (No. 062452) and a project Grant (No. 085396) from the Wellcome Trust. PG & EK were part funded by the Department of Health via the National Institute for Health Research (NIHR) Specialist Biomedical Research Centre for Mental Health award to South London and Maudsley NHS Foundation Trust (SLaM) and the Institute of Psychiatry at King’s College, London. DFr is supported by a Medical Research Council (MRC) Senior Clinical Fellowship.
We wish to thank the patients taking part in the studies and the participating teams in the four NHS Trusts—South London & Maudsley NHS Foundation Trust, North East London NHS Foundation Trust, Camden & Islington NHS Foundation Trust, Norfolk & Waveney Mental Health NHS Foundation Trust.