Severe Mental Disorders from a Cognitive-Behavioural Perspective: A Comprehensive Review from Conceptualization to Intervention

Research has shown that hallucinations and delusions (characteristic of severe mental disorders) are relatively common. Many people in the general population will experience mild instances of such events at some point in their lives. However, for others, these are very disturbing events. Cognitive-behavioural models argue that these differences result from the interpretation of those same experiences. Therefore, cognitive behavioural therapy seeks to know the factors that contribute to the development (e.g. early traumatic experiences) and maintenance (e.g. selective attention, safety behaviours, disruptive control strategies) of psychotic processes, from the deep and isolated understanding of each patient’s experience of specific symptoms (e.g. paranoid delusions) rather than their syndromal diagnosis (e.g. schizophrenia). The case formulation for each complex psychotic symptom results from the initial intake assessment at the start of a prospective intervention. This article reviews the cognitive behavioural conceptualization of psychotic symptoms (i.e. auditory hallucinations, delusions and negative symptoms), as well as the key areas of assessment and therapeutic interventions proposed by these models. Key-words: Cognitive-Behavioural Therapy; Psychosis; Hallucinations; Delusions A growing number of meta-analyses have supported the use of Cognitive Behavioural Therapy (CBT) in the treatment of psychosis [1-14]. Overall, findings suggests that cognitive behaviour therapy for people with psychosis (CBTp) can be beneficial in reducing positive and negative symptoms, hallucinations and delusions, while also improving overall functioning and level of disability, both during post-intervention and follow-up. In one of the most recent studies [1], a systematic review and meta-analysis of 10 controlled trials evaluating low intensity CBT (i.e. fewer than 16 therapy contact hours) dealing with psychosis symptom outcomes, found significant between-group effects on psychosis symptoms during postintervention (d=−0.46) and follow-up (d=−0.40). It showed that low intensity CBTp led to significant post-intervention, between group differences in psychotic symptoms compared to control conditions with a medium effect size. Where follow-up was measured, this effect was maintained, with the follow-up time period ranging from 3 to 18 months. Pfammatter, [2] in a systematic review of findings of all relevant meta-analyses on CBT in the treatment of psychosis, demonstrates considerable differences in controlled efficacy; CBT for psychosis has long-term effects on the persistence of positive and negative symptoms, yet without any effect on acute positive symptoms and with limited benefits as an early intervention. Gould et al. [3] conducted a meta-analysis using all available controlled treatment outcome studies of cognitive therapy (CT) for psychotic symptoms in schizophrenia. The mean effect size for reduction of psychotic symptoms was 0.65. The findings suggest that cognitive therapy is an effective treatment for patients with schizophrenia with persistent psychotic symptoms. Follow-up analyses in four studies indicated that patients receiving CT continued to make gains over time (ES=0.93). Philling et al. [4] conducted a meta-analysis of a wider range of randomized controlled trials and compared both standard care and other active interventions. As in other meta-analyses, CBT produced higher rates of significant improvement in mental state and demonstrated positive effects on continual measures of mental state at follow-up. CBT also seems to be associated with low dropout rates. Wykes et al. [5] in a meta-analysis of thirty-four CBTp trials, found overall beneficial effects for the target symptom (d = 0.40) as well as significant effects for positive symptoms (32 studies), negative symptoms (23 studies), functioning (15 studies), mood (13 studies), and social anxiety (2 studies) with effects ranging from 0.35 to 0.44. Dickerson [6], in another meta-analysis, reviews seventeen CBTp studies and found the strongest evidence for the benefit of that to outpatients with residual symptoms including hallucinations, delusions, or negative symptoms. Turner et al. [7] conducted a meta-analysis of comparative outcome studies of psychological interventions for psychosis. Forty-eight outcome trials, with 3,295 participants, compared psychological interventions for psychosis. Results showed that cognitive-behavioural therapy was significantly more efficacious than other interventions in reducing positive symptoms (g=0.16). In another meta-analysis, van der Gaag et al. [8] reviewed eighteen studies of CBT using individually tailored case formulations aimed at reducing hallucinations and delusions. The statistically significant effect-sizes were 0.36 for delusions and 0.44 for hallucinations. Contrasted with active treatment, CBT for delusions lost statistical significance (0.33), but the effect-size for CBT for hallucinations increased (0.49). Blinded studies reduced effect-size in delusions (0.24) and increased it somewhat in hallucinations (0.46). The authors conclude that CBT is effective in treating auditory hallucinations. CBT is also effective for delusions, but the results must be interpreted with caution, because of the heterogeneity and the non-significance of effect-sizes when compared with active treatment [12]. Velthorst et al. [9] reviewed all available evidence regarding the factors contributing to the improvement of negative symptoms and the identification of subgroups of patients that may benefit the most from CBT directed at ameliorating negative symptoms. A total of 35 publications covering 30 trials in 2,312 patients, published between 1993 and 2013, were included. The results showed studies' pooled effect on symptom alleviation to be small and heterogeneous in studies with negative symptoms as a secondary outcome. Similar results were found for studies focused on negative symptom reduction. Meta-regression revealed that stronger treatment effects were associated with earlier year of publication, lower study quality and with CBT provided individually (as compared with group-based). There has been some debate about the degree of effect of CBTp [15]. However, taking into account the severity of the psychotic disorders and the lack of other proven effective therapeutic responses, these findings should be sufficient to defend the use of CBTp (as a primary or adjunctive therapy) to help reduce the suffering of patients with severe mental disorders. 1. Understanding serious mental disorders The cognitive behavioural therapeutic approach is based on two central theoretical assumptions: (1) that thought influences affect, behaviour and biology, and (2) that it is not the events themselves that disturb people but the interpretation they make of them [16]. In addressing serious mental disorders, cognitive behavioural models focus on specific experiences (e.g. auditory hallucinations, persecutory delusions, delusions of grandeur), rather than global diagnoses (e.g. schizophrenia) when trying to understand the vulnerability factors, activators events and maintenance factors involved in each of these specific symptoms. The complexity of the psychotic experience requires a idiosyncratic formulation for each. Cognitive-behavioural case formulation provides insight into how life experiences and reactions to events have led to patients’ particular interpretation of voices and strange thoughts. This personal explanation allows therapists to understand how patients’ reactions are understandable and justified in their eyes. 2. Understanding auditory hallucinations The cognitive-behavioural model considers auditory hallucinations to be relatively "normal" experiences. In fact, it is relatively common for people from non-clinical populations to hear voices [17]. Research shows that individuals experiencing auditory hallucinations had a bias towards externally attributing their internal and private cognitions, suggesting a relation between voices and inner speech [18,19]. Based on empirical evidence, it is arguable that people who hear voices are actually misinterpreting their own thoughts as speech that they then attribute to an external source. This misinterpretation seems to be more likely to occur in environments with many different auditory stimuli (e.g. a noisy coffee shop) or in the absence of any external auditory stimulus. From this perspective, more than the experience of hearing voices, it is the meaning that each person attributes to those voices and the way they react to hearing them that determine the disturbing nature of the experience. For example, during bereavement for a loved one, it is not unusual to hear the voice of the person who has died. Some people consider this to be relatively understandable and undisturbing. This happens when people make positive attributions to hearing voices (e.g. as a sign that the person "is still with me"), or they realize that hearing voices can be seen as related to experiencing life stress. However, if people attribute the voice to malevolent external sources from which they feel the need to protect themselves, their answers will be very different. So it is the meaning, the type of meaning attributed to the voices i.e., how they threaten patients’ psychological or physiological personal integrity (e.g. "I'm going crazy," "the devil is talking to me", "if I not obey voices they will hurt me") and the resulting reactions to them (i.e. adoption of safety behaviours) that determine the person's relationship to the voice(s). Hallucinations are problematic when they are interpreted by the patients as representing powerful and destructive forces. The set of cognitive, emotional and behavioural reactions will be determined by who we are, by previous experiences we have had, as well as by the context in which the voices occurs [19,20]. Hearing voices may arise in response to particularly stressful lif