هذیان و سبک تصمیم گیری: استفاده از نیاز برای آزمون تعطیلی

Abstract Clinicians and researchers have suggested that rapidity in belief formation, due to having a high ‘need for closure’ (NFC), may contribute to the acceptance of delusional explanations. The aim of the study is to determine whether NFC has such a direct link with delusions. A secondary aim is to examine if NFC is related to the delusion-associated reasoning process of ‘jumping to conclusions’. One hundred and eighty-seven patients with psychosis, recruited for a treatment trial of psychological therapy (the PRP trial), completed the Need for Closure Scale (NFCS), symptom measures, and probabilistic reasoning tasks. The NFCS was considered in terms of its two dimensions: a desire for simple structure and a preference for quick, decisive answers. The individuals with psychosis reported being poor at making quick, decisive answers but required a greater need for simple structure. NFC was associated with levels of anxiety and depression. There were weak links between NFC and both positive and negative symptoms of psychosis, but these were explained by differences in affect. NFCS scores were unrelated to jumping to conclusions. Contrary to the argument that NFC is directly linked to delusions, individuals with delusions actually perceive themselves as indecisive. There was no evidence that NFC—at least as assessed by the NFCS—could be a proximal cause of delusions. Any potential effect on psychotic symptom presentation is indirect, mediated through affect. The use of the NFCS on its own in the study of psychotic symptoms cannot be recommended.

The idea that individuals with delusions have a high ‘need for closure’ (NFC) is theoretically and clinically appealing. Delusions are often attempts to make sense of a range of confusing and puzzling experiences, and difficulties dealing with uncertainty would be likely to facilitate rapid acceptance of explanations even if they are implausible. In cognitive-behavioural interventions patients are encouraged to be less certain in their judgements and to slow their decision-making processes down in order to consider other evidence and explanations. This can be conceptualised as an attempt to reduce closure. NFC is therefore one of a number of reasoning biases that may be implicated in delusion formation and persistence.

Clinical and demographic data The mean age of the patient group was 37.5 years (SD=10.9). There were more male (n=134n=134) than female (n=53n=53) participants. The group comprised the following ethnicities: White (n=137n=137), Black—African (n=12n=12), Black—Caribbean (n=15n=15), Black—Other (n=5n=5), Indian (n=5n=5), Other (n=13n=13). The case note diagnoses were schizophrenia (n=165n=165), schizo-affective disorder (n=20n=20), and delusional disorder (n=2n=2). The mean length of illness was 10.2 years (SD=8.4). The mean PANSS Positive symptom score was 17.8 (SD=5.3), the mean PANSS Negative symptom score was 13.1 (SD=6.0) and the mean PANSS General Psychopathology score was 33.2 (SD=7.9). For comparison, the mean scores from 101 people from a long-term psychiatric unit reported by Kay et al. (1987) in their development of the PANSS were: PANSS Positive=18.2 (SD=6.1), PANSS Negative=21.0 (SD=6.2), and PANSS General Psychopathology=37.7 (SD=9.5). Thus the current relapsing sample had the same level of positive symptoms but lower levels of negative symptoms compared with a chronic group. The mean BDI score (n=186n=186) was 21.6 (SD=13.0) and the mean BAI score (n=182n=182) was 19.9 (SD=14.4). The comparison group had a mean age of 22.6 (SD=5.9) and the sex ratio was skewed towards female participants (n=227n=227). The mean DASS-Depression score was 9.2 (SD=9.7) and the mean DASS-Anxiety score was 6.7 (SD=7.7).