Delusions in the nonclinical population

Department of Psychology, PO Box 77, Institute of Psychiatry, Kings College London, Denmark Hill, London SE5 8AF, UK.
Current Psychiatry Reports (Impact Factor: 3.24). 06/2006; 8(3):191-204. DOI: 10.1007/s11920-006-0023-1
Source: PubMed


Delusions have long been considered a hallmark of psychotic disorders such as schizophrenia. However, delusions may only be most visibly present in psychotic conditions and could also occur in nonclinical groups. The aim of this review is to establish whether delusions, as traditionally considered and assessed in psychiatric conditions, are also present in individuals without a psychiatric or neurologic condition. Clear evidence is found that the rate of delusional beliefs in the general population is higher than the rate of psychotic disorders and that delusions occur in individuals without psychosis. The frequency of delusional beliefs in nonclinical populations varies according to the content of the delusion studied and the characteristics of the sample population. Approximately 1% to 3% of the nonclinical population have delusions of a level of severity comparable to clinical cases of psychosis. A further 5% to 6% of the nonclinical population have a delusion but not of such severity. Although less severe, these beliefs are associated with a range of social and emotional difficulties. A further 10% to 15% of the nonclinical population have fairly regular delusional ideation. There is convincing evidence that delusional ideation, delusions, and clinically severe delusions are related experiences. Information about clinical delusions can therefore be obtained by studying delusional ideation in nonclinical populations.

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    • "A hubris account of paranoia Delusions are traditionally associated with schizophrenia but are in fact a transdiagnostic, symptom, which are present in many psychiatric disorders. Benign subclinical paranoid beliefs are encountered in 15-20% of the population (Freeman, 2006; Stip & Letourneau, 2009; van Os & Kapur, 2009). "
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    Journal of Behavior Therapy and Experimental Psychiatry 12/2015; 48. DOI:10.1016/j.jbtep.2015.02.011 · 2.23 Impact Factor
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    • "Interestingly, there is converging evidence that such unfounded beliefs in the healthy lie on a continuum with delusions in individuals suffering from psychosis (Freeman, 2006; Linscott and van Os, 2013; Zavos et al., 2014), and alterations in the self-related processes have been demonstrated for both unfounded beliefs in the healthy (Fenigstein and Vanable, 1992) and delusions in psychotic individuals (Smári et al., 1994). This suggests that the tendency toward unfounded beliefs represents a continuously distributed phenotype that in its extreme form can lead to significant distress and social isolation. "
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    Frontiers in Human Neuroscience 09/2015; 9. DOI:10.3389/fnhum.2015.00521 · 3.63 Impact Factor
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    • "132). Echoing this, Freeman (2006) suggested that delusions are commonly found in the general (non-clinical) population , among individuals without psychosis. Approximately 1–3% of the non-clinical population were estimated to have delusions of a level of severity comparable to clinical cases of psychosis, with a further 5–6% having delusions of lesser severity that were nonetheless associated with a range of social and emotional difficulties. "
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