Background: Psychosis exists in the community as a continuum of severity. Here, we examine the correlates of self-reported psychotic symptoms in an urban catchment area of Iran. Sampling and Methods: Two thousand one hundred and fifty-eight participants (age 18–65 years) residing in southern Tehran (the capital city of Iran) were interviewed using the psychoticism and paranoia dimensions of the Symptom Checklist-90-Revised (SCL-90-R) to assess the severity of psychotic symptoms. Other dimensions of the SCL-90-R assessing nonpsychotic symptoms and a sociodemographic questionnaire were also used. Paykel’s Interview for Recent Life Events was used to assess stressful life events. Results: Independent associations were observed between younger age, female gender, stressful life events and dimensions of depression, anxiety, hostility, obsessive-compulsive symptoms and interpersonal sensitivity and psychoticism. Independent associations were also observed for marital problems, unemployment, stressful life events and dimensions of depression, anxiety, hostility, interpersonal sensitivity and phobic anxiety with paranoid ideation. There was also a trend toward an association between higher educational levels and the severity of psychotic symptoms, particularly paranoid ideation. Conclusions: Most of the previously accepted correlations for psychotic symptoms in the community were replicated. An unexpected association between paranoia and female gender, and a trend toward higher rates of psychotic symptoms in more educated participants, were in contrast with the studies in developed settings. The insufficient coverage of psychosis-relevant questions from the SCL-90-R for the entire psychotic diagnostic spectrum should be considered a limitation.

Psychotic symptoms such as hallucinations and delusions are commonly reported at subclinical levels in the community [1,2,3,4,5]. It has been shown that self-reported psychotic experiences in general population samples lie on a continuum with psychotic symptoms in clinical samples [6]. In 2000, a 15-year follow-up by Poulton et al. [7] showed that high rates of psychotic experiences in adolescence predicted schizophreniform diagnosis at the age of 26 years. This association was specific to schizophreniform diagnosis and due to the link between child and adult psychotic symptoms. These results were replicated in a 21-year longitudinal study by Welham et al. [8] in which nonaffective psychosis was predicted by increased psychopathology during childhood and adolescence.

The risk factor profile of these nonclinical symptoms has been reported to be similar to that of clinical disorders [2,6], has been regarded as disabling [9] and has been associated with violent behavior in at least one study [10]. A recent review of the population studies of risk factors for psychotic symptoms [11] outlined the previously shown associations of nonclinical psychotic symptoms with stressful life events [4,12,13,14], single and divorced marital status [2,5], unemployment [5,9], lower socioeconomic status [2,4,5,12] and nonpsychotic symptoms such as depression [2,7,13,15,16,17], anxiety [7,18,19,20] and hostility [21,22,23]. In addition, psychotic experiences have been shown to be associated with younger age [1,2,4,6,24] and some neurotic symptoms such as phobias [25,26], obsessive-compulsive symptoms [25,27], somatoform experiences [27,28,29] and interpersonal problems [30,31,32]. Depression, anxiety and interpersonal problems have been further reported to be commonly observed in the prodromal phase of psychotic disorders [20].

Despite the rich body of literature regarding psychotic experiences in the general population, there is a lack of related studies in developing countries of the Middle East. Considering the need for transcultural collaborations in this field, we decided to determine the correlates of self-reported psychotic symptoms in an urban general population in Iran.


This study was a secondary analysis of data from a population-based cross-sectional study in Tehran, Iran [33]. The study population consisted of 18- to 65-year-old individuals residing in the catchment area of the Abouzar health center. This is a densely populated region in the southern part of Tehran, the capital city of Iran, whose inhabitants mostly belong to the lower socioeconomic classes of the capital. The sample comprised 2,158 participants.

The sampling method was a two-stage random sampling from the households in the area. In the first stage, 5 out of 8 districts located in the area of the research center were selected by simple random sampling. In the second stage, 2,158 people from the selected age range living in the 5 districts were recruited to the study and interviewed by systematic random sampling. If the selected participant was not present in the house or unable to provide a coherent interview, the interviewer left for the next dwelling. The refusal rate was low, at 4%.


To assess self-reported psychotic symptoms, we used the questions from two dimensions of the Symptom Checklist-90-Revised (SCL-90-R), namely ‘paranoid ideation’ and ‘psychoticism’ [34]. The SCL-90-R is a relatively brief self-report psychometric instrument (questionnaire) designed to evaluate a broad range of psychological problems and symptoms of psychopathology. The instrument is also useful for measuring patient progress or treatment outcomes. The 90 items of the SCL-90-R are grouped along 9 symptom dimensions reflecting broad psychological symptom status. ‘Paranoid ideation’ is a 6-item dimension that is characterized by projective thoughts, hostility, suspiciousness, grandiosity, centrality, fear of loss of autonomy and delusions. The ‘psychoticism’ dimension (10 items) includes items indicative of a withdrawn, isolated and schizoid lifestyle as well as items representing symptoms of psychosis and schizophrenia, such as hallucination and thought broadcasting. Other dimensions of the SCL-90-R were used to study the other mental (nonpsychotic) associates of the psychotic symptoms. These include depression, anxiety, phobic anxiety, somatization, hostility, obsessive-compulsive symptoms and interpersonal sensitivity. Participants responded on a 5-point Likert scale of distress ranging from ‘not at all’ (0) to ‘a little bit’ (1), ‘moderately’ (2), ‘quite a bit’ (3) and ‘extremely’ (4). The time period covered by the SCL-90-R in this study was 4 weeks. The SCL-90-R has shown good consistency and test-retest reliability [35,36]. Its Persian-language version has also been reported to have adequate psychometric properties [37]. However, its interpretability and utility as a self-report measure have been criticized. Denial, minimization of symptoms and bias are three mechanisms which could cause inaccurate reports [38]. To examine these mechanisms for the two psychosis-relevant dimensions in the present study setting, we ran a parallel study to detect the discriminative validity and the resultant utility of these two dimensions. The self-reported scores of a group of 90 psychiatric patients were compared with their clinician-based DSM-IV diagnoses. The sample consisted of 34 patients clinically diagnosed with nonpsychotic disorders or psychotic disorders in remission, 29 patients with psychotic disorders and 27 patients with nonpsychotic disorders with psychotic features. The interviewers were blinded to the clinical diagnosis of the participants. A univariate analysis of variance (ANOVA) was used to compare the three diagnostic groups with regard to the means of their self-reported scores for the paranoid ideation and psychoticism dimensions.

For stressful life events, we used Paykel’s Interview for Recent Life Events [39]. The participants were asked whether they had experienced any of the life events in the interview during the past 6 months and to describe the amount of psychological distress from each life event, scored from 1 to 20. We defined 2 variables for stressful events, i.e. the frequency (number) of stressful life events experienced in the last 6 months and the sum of the scores of the distressfulness of life events for each person in the same period. The Persian-language version of the instrument has been shown to be highly reliable [40].

Participants were interviewed by 15 health technicians and paramedical students. The interviewers were trained in a 3-day workshop and 1 briefing session with a master-level expert in clinical psychology. All the participants signed the informed consent forms, and confidentiality was protected. If the participants were illiterate, the questions were read to them and their answers were recorded.

Statistical Analysis

Analyses were conducted using the Statistical Package for Social Sciences, version 16. The two dimensions of psychotic symptoms from the SCL-90-R (paranoid thoughts and psychoticism) yield a score which arises from summing the scores for different questions in each dimension (0 to 23 for paranoid ideation and 0 to 40 for psychoticism). To examine the association of the above-mentioned nonpsychotic symptoms, stressful life events and demographic variables with the psychotic dimensions, we performed χ2 tests, Pearson correlations, ANOVAs, independent-sample t tests and linear regressions.

The study sample consisted of 2,158 participants with a mean age of 33.17 years (SD 12.45), 1,159 of whom were female (54.7%).

With regard to marital status, there were 5 categories: single (30.3%, n = 653), widowed (2.4%, n = 51), separated (0.45%, n = 9), married (66.4%, n = 1,432) and divorced (0.5%, n = 11). For educational attainment, there were 5 defined levels: illiterate (10.8%, n = 233), primary (18.6%, n = 402), intermediate (23.9%, n = 515), high school (37.5%, n = 810) and university degree (9.2%, n = 198). For job status, there were 5 categories: homemaker (40.3%, n = 869), laborer (8.6%, n = 186), employer (12.7%, n = 273), self-employed (17.1%, n = 370) and unemployed (11%, n = 237).

The average monthly income of the family caretaker in USD was divided into 4 categories: 62.5–93.75 (13.3%, n = 286), 93.75–125 (25.1%, n = 541), 125–156.25 (24.1%, n = 521) and 125–187.5 (19.9%, n = 430).

When considering the test for discriminative validity of the self-reported psychotic symptoms, using the data from psychiatric patients, a univariate ANOVA showed significant between-subject effects for both the paranoid ideation (F = 11.7, d.f. = 2, p < 0.01) and psychoticism dimension (F = 8.2, d.f. = 2, p < 0.01). Post hoc analysis (Tukey’s honestly significant difference test) revealed that the patients with nonpsychotic disorders or psychoses in remission scored significantly lower on both dimensions (mean = 7.1, SD = 4.5 for paranoid ideation, and mean = 7.3, SD = 6 for psychoticism) than either the patients with psychotic disorders (mean = 12.9, SD = 4.7 for paranoid ideation, and mean = 13.4, SD = 7 for psychoticism) or the patients with nonpsychotic disorders with psychotic features (mean = 10.4, SD = 4.8 for paranoid ideation, and mean = 12.2, SD = 6.3 for psychoticism). The latter two groups did not show a significant difference from each other on either dimension. The results showed that the two self-reporting psychosis-relevant dimensions of the SCL-90-R were capable of detecting the psychotic symptoms in the present study setting.

Both SCL-90-R dimensions of psychosis were correlated with age, stressful life events and the dimensions of depression, anxiety, phobic anxiety, somatization, hostility, obsessive-compulsive symptoms and interpersonal sensitivity (table 1).

Table 1

Correlation between two dimensions of psychosis in the SCL90-R (psychoticism and paranoid ideations) and age, stressful life events and nonpsychotic symptom dimensions in the SCL90-R

Correlation between two dimensions of psychosis in the SCL90-R (psychoticism and paranoid ideations) and age, stressful life events and nonpsychotic symptom dimensions in the SCL90-R
Correlation between two dimensions of psychosis in the SCL90-R (psychoticism and paranoid ideations) and age, stressful life events and nonpsychotic symptom dimensions in the SCL90-R

The severity of paranoid ideation and psychoticism was significantly higher among female compared with male participants. The mean paranoid ideation scores were not different across categories for marital status, but mean psychoticism scores showed a significant difference across these categories. There were significant differences across educational levels, job categories and income levels for both dimensions of psychosis, and contrary to our expectations, there was a trend toward more symptoms in subjects with higher levels of education (F = 19.44, d.f. = 1, p < 0.01, R = 0.094, and F = 2.89, d.f. = 1, p < 0.01, R = 0.06, for tests of linearity regarding paranoid and psychoticism symptoms, respectively). No significant linear trends were detected for the effect of income levels on the severity of psychotic symptoms. Table 2 shows the scores on both dimensions for the above-mentioned groups.

Table 2

Comparison of psychotic symptom dimensions across different subgroups of demographic variables

Comparison of psychotic symptom dimensions across different subgroups of demographic variables
Comparison of psychotic symptom dimensions across different subgroups of demographic variables

When considering nonpsychotic symptoms, a multiple regression analysis with a backward elimination method showed a significant positive linear correlation between the psychoticism dimension and the dimensions of depression, anxiety, hostility, phobias and interpersonal sensitivity. There was also a significant positive linear correlation between paranoid ideation and the dimensions of depression, anxiety, hostility, obsessive-compulsive symptoms and interpersonal sensitivity (table 3).

Table 3

Final multiple regression models examining associations between sociodemographic variables and nonpsychotic symptoms using ‘paranoid ideations’ and ‘psychoticism’ as dependent variables

Final multiple regression models examining associations between sociodemographic variables and nonpsychotic symptoms using ‘paranoid ideations’ and ‘psychoticism’ as dependent variables
Final multiple regression models examining associations between sociodemographic variables and nonpsychotic symptoms using ‘paranoid ideations’ and ‘psychoticism’ as dependent variables

For paranoid ideation, additional associations were observed for age, sex and the frequency of stressful life events. There was also a trend toward a positive correlation between paranoid ideation and educational levels in the final regression model (p = 0.073). For the psychoticism dimension, further associations were observed between the sum of the distressfulness of stressful life events, marital status and job status. No significant association was observed between income level and either dimension of psychosis (table 3).

We observed strong associations between dimensions of nonpsychotic symptoms and self-reported psychotic symptoms from dimensions on the SCL-90-R, with some exceptions (e.g. somatization was not associated with either of the dimensions, phobia was not associated with paranoia and the obsessive-compulsive dimension was not associated with psychoticism). Nevertheless, because our study used a cross-sectional design, disentangling the exact nature of these associations is not possible, and we cannot know whether these reported psychotic symptoms are a part of these nonpsychotic syndromes or whether the nonpsychotic syndromes are triggered by these psychotic symptoms [17]. Another theory proposed is that psychotic symptoms are risk factors for both psychotic and mood disorders [17].

As reported in previous studies, age was shown to be negatively correlated with both aspects of psychosis, albeit with a small R value (table 1). Linear regression confirmed these results for paranoid ideation but not for the psychoticism aspect of psychosis. The same results were shown in the British National Psychiatric Morbidity Survey [4], in which there was a significant association between age and paranoid thoughts and no association between age and psychotic and hallucinatory experiences. Indeed, the dimensional view of the correlation between the intensity of psychotic symptoms and age, which has some supporting evidence [24,41], requires more attention in future studies.

The intensity of stressful life events was shown to be associated with both aspects of psychosis, which is in line with the evidence for a predictor role of these events in the proposed stress-gene interaction model for the prediction of psychosis [42].

We observed a higher severity of psychoticism and paranoid ideation among women, which was supported by the multiple regression analysis for paranoia. In general, the prevalence of nonclinical psychotic symptoms seems to be equal for both genders, with more negative symptoms and paranoid ideation in males and more hallucinations and magical thinking for females [4,43,44,45]. Our results indicating more paranoid ideation observed in females were contrary to some previous research findings [4,46,47]. This observation requires further replication in other studies before a hypothesis can be proposed.

In line with previous research, single or divorced marital status and unemployment were reported to be correlated with the psychoticism dimension of our questionnaire, which includes core schizophrenia symptoms in the first four questions. However, contrary to previous work, we failed to confirm the associations between psychotic symptoms and lower income and lower education in secondary analysis. Unexpectedly, we observed a trend in which people with higher educational levels showed higher rates of psychotic symptoms in post hoc analyses. Moreover, there was a tendency toward a positive linear correlation between educational level and paranoid symptoms, which is in contrast with most previous studies that have indicated that more paranoid symptoms are associated with lower levels of education. The idea has been postulated in one other study – and, interestingly, in a nondeveloped setting like the present study – that there is a strengthening effect of higher education on the prevalence of delusional ideation for urban dwellers [48]. Those authors correlated this phenomenon with more aspirations and ambitions and more resultant disappointments due to a lack of infrastructure for this more educated group. They have proposed that the resulting discrepancy between this educated group’s notion of actual self and ideal self is a mechanism for delusional ideas. It seems that this trend needs more investigation as it relates to psychopathology in developing countries.

Our study sample size seems to be large enough to generalize the results, but the self-rating nature of the instrument (SCL-90-R) requires reliance on individuals to correctly interpret their conditions. This creates limitations for the instrument to assess psychotic symptoms [37]. Through a parallel study, we demonstrated the capability of the self-report to assess the two psychosis-relevant dimensions of the SCL-90-R in the present study setting. There is at least one other study that proves the capability for the other dimensions of the SCL-90-R in the Iranian population [49]. Moreover, not all the symptoms required in the DSM-IV and ICD-10 for the diagnosis of schizophrenia, schizotypal personality disorders or other psychotic disorders are part of the SCL-90-R, and therefore some symptoms are not included in our study. Another limitation was the uncertain nature of the two dimensions of psychosis in the SCL-90-R [35,50], which necessitates confirmatory factor analyses in future studies.

In conclusion, in a nondeveloped setting, we found that the severity of psychotic symptoms in the general population correlated with stressful life events and most of the nonpsychotic symptoms. However, we were unable to make any judgment on the nature of the associations. Social losses, such as marital loss and unemployment, showed correlations with the psychoticism dimension of the SCL-90-R, including the core schizophrenia symptoms. A dimensional correlation between psychotic symptoms and age was also observed. In contrast with some previous studies, there were higher scores on paranoid ideas for females and a tendency for more educated participants to show more psychotic symptoms. Further research about the real nature of these correlations should be conducted.

This study was supported by a grant from Tehran University of Medical Sciences. The authors are grateful to the staff of the Abouzar Health Center and the authorities at the Tehran Municipality. The authors wish to thank Mrs. H. Noktehdan, Dr. F. Bathai, Mrs. M. Kiani and Mr. H. Bakhtiari for their kind help.

Kendler KS, Gallagher TJ, Abelson JM, Kessler RC: Lifetime prevalence, demographic risk factors, and diagnostic validity of nonaffective psychosis as assessed in a US community sample. The National Comorbidity Survey. Arch Gen Psychiatry 1996;53:1022–1031.
Van Os J, Hanssen M, Bijl RV, Ravelli A: Strauss (1969) revisited: a psychosis continuum in the general population? Schizophr Res 2000;29:11–20.
Spauwen J, Krabbendam L, Lieb R, Wittchen HU, Van Os J: Sex differences in psychosis: normal or pathological? Schizophr Res 2003;1:45–49.
Johns LC, Cannon M, Singleton N, Murray RM, Farrell M, Brugha T, Bebbington P, Jenkins R, Meltzer H: Prevalence and correlates of self-reported psychotic symptoms in the British population. Br J Psychiatry 2004;185:298–305.
Scott J, Chant D, Andrews G, Mcgrath J: Psychotic-like experiences in the general community: the correlates of CIDI psychosis screen items in an Australian sample. Psychol Med 2006;36:231–238.
Verdoux H, Van Os J: Psychotic symptoms in non-clinical populations and the continuum of psychosis. Schizophr Res 2002;54:59–65.
Poulton R, Caspi A, Moffitt TE, Cannon M, Murray R, Harrington H: Children’s self-reported psychotic symptoms and adult schizophreniform disorder: a 15-year longitudinal study. Arch Gen Psychiatry 2000;57:1053–1058.
Welham J, Scott J, Williams G, Najman J, Bor W, O’Callaghan M, McGrath J: Emotional and behavioural antecedents of young adults who screen positive for non-affective psychosis: a 21-year birth cohort study. Psychol Med 2009;39:625–634.
Olfson M, Lewis-Fernandez R, Weissman MM, Feder A Gameroff MJ, Pilowsky D, Fuentes M: Psychotic symptoms in an urban general medicine practice. Am J Psychiatry 2002;159:1412–1419.
Mojtabai R: Psychotic-like experiences and interpersonal violence in the general population. Soc Psychiatry Psychiatr Epidemiol 2006;41:183–190.
Kelleher I, Cannon M: Psychotic-like experiences in the general population: characterizing a high-risk group for psychosis. Psychol Med 2011;41:1–6.
Bazargan M, Bazargan S, King L: Paranoid ideation among elderly African American persons. Gerontologist 2001;41:366–373.
Freeman D, Dunn G, Garety PA, Bebbington P, Slater M, Kuipers E, Fowler D, Green C, Jordan J, Ray K: The psychology of persecutory ideation I: a questionnaire survey. J Nerv Ment Dis 2005;193:302–308.
Wiles NJ, Zammit S, Bebbington P, Singleton N, Meltzer H, Lewis G: Self-reported psychotic symptoms in the general population: results from the longitudinal study of the British National Psychiatric Morbidity Survey. Br J Psychiatry 2006;188:519–526.
Krabbendam L, Myin-Germrys I, de Graaf R, Vollebergh W, Nolen WA, Iedema J, Van Os J: Dimensions of depression, mania and psychosis in the general population. Arch Gen Psychiatry 2004;34:1177–1186.
Yung AR, Buckby JA, Cosgrave EM, Killackey EJ, Baker K, Cotton SM, McGorry PD: Association between psychotic experiences and depression in a clinical sample over 6 months. Schizophr Res 2007;91:246–253.
Yung AR, Buckby JA, Cotton SM, Cosgrave EM, Killackey EJ, Stanford C, Godfrey K: Psychotic-like experiences in nonpsychotic help-seekers: associations with distress, depression, and disability. Schizophr Bull 2006;32:352–359.
Ohayon MM: Prevalence of hallucinations and their pathological associations in the general population. Psychiatry Res 2000;27:153–164.
Freeman D, Garety PA, Bebbington P, Slater M, Kuipers E, Fowler D, Green C, Jordan J, Ray K, Dunn G: The psychology of persecutory ideation. II. A virtual reality experimental study. J Nerv Ment Dis 2005;193:309–315.
Salokangas RK, Mcglashan TH: Early detection and intervention of psychosis. A review. Nord J Psychiatry 2008;62:92–105.
Brugha T, Singleton N, Meltzer H, Bebbington P, Farrell M, Jenkins R, Coid J, Fryers T, Melzer D, Lewis G: Psychosis in the community and in prisons: a report from the British National Survey of psychiatric morbidity. Am J Psychiatry 2005;162:774–780.
Nielssen O, Misrachi S: Prevalence of psychoses on reception to male prisons in New South Wales. Aust NZ J Psychiatry 2005;39:453–459.
Nishida A, Tanii H, Nishimura Y, Kajiki N, Inoue K, Okada M, Sasaki T, Okazaki Y: Associations between psychotic-like experiences and mental health status and other psychopathologies among Japanese early teens. Schizophr Res 2008;99:125–133.
Verdoux H, van Os J, Maurice-Tison S, Gay B, Salamon R, Bourgeois M: Is early adulthood a critical developmental stage for psychosis proneness? A survey of delusional ideation in normal subjects. Schizophr Res 1998;29:247–254.
Cassano G, Pini S, Saettoni M, Rucci P, Dell’osso L: Occurrence and clinical correlates of psychiatric comorbidity in patients with psychotic disorders. J Clin Psychiatry 1998;59:60–68.
Cassano GB, Pini S, Saettoni M, Dell’osso L: Multiple anxiety disorder comorbidity in patients with mood spectrum disorders with psychotic features. Am J Psychiatry 1999;156:474–476.
Schafer MR, Klier CM, Papageorgiou K, Friedrich MH, Amminger GP: Early detection of psychotic disorders (in German). Neuropsychiatr 2007;21:37–44.
Phillips KA: Psychosis in body dysmorphic disorder. J Psychiatr Res 2004;38:63–72.
Van Der Zwaard R, De Leeuw AS, Van Dael F, Knook LM: ...with psychotic features? An investigation into the delusional nature of convictions in patients with non-psychotic disorders (in Dutch). Tijdschr Psychiatr 2006;48:461–466.
Martin JA, Penn DL: Social cognition and subclinical paranoid ideation. Br J Clin Psychol 2001;40:261–265.
Addington J, Penn D, Scott W, Woods SW, Addington D, Perkins DO: Social functioning in individuals at clinical high risk for psychosis. Schizophr Res 2008;99:119–124.
Freeman D, Gittins M, Pugh K, Antley A, Slater M, Dunn G: What makes one person paranoid and another person anxious? The differential prediction of social anxiety and persecutory ideation in an experimental situation. Psychol Med 2008;38:1121–1132.
Faghih-Nasiri L, Sharifi V, Hatmi Z, Sadeghianmehr Z, Mirkia SH, Darbooy SH, Effatpanah M, Mirsharifa SM: Prevalence of stressful factors and psychiatric symptoms among individuals under the care of Abouzar health and medical center. Adv Cogn Sci 2006;8:47–53.
Derogatis LR: SCL90. Administration, Scoring and Procedures. Manual-1 for the R (revised) Version and Other Instruments of the Psychopathology Rating Scale Series. Chicago, Johns Hopkins University School of Medicine, 1977.
Derogatis LR, Cleary PA: Confirmation of the dimensional structure of the SCL-90: a study in construct validity. J Clin Psychol 1977;33:981–989.
Schmitz N, Hartkamp N, Kiuse J, Franke GH, Reister G, Tress W: The Symptom Check-List-90-R (SCL-90-R): a German validation study. Qual Life Res 2000;9:185–193.
Pourshahbaz A: The relation between the evaluation of stressful life events rates and personality in the oncology patients; dissertation, Tehran Psychiatry Institute, Tehran, 1995.
Eisen SV, Leff HS, Schaefer E: Implementing outcome systems: lessons from a test of the BASIS-32 and the SF-36. J Behav Health Serv Res 1999;26:18–27.
Paykel ES: Methodological aspects of life events research. J Psychosom Res 1983;27:341–352.
Mohajer M, Motaghipour Y, Katuzian B: Ranking for stressful life events: an investigation in a group of Shahid Beheshti university students. Pejouhesh 1990;14:33–48.
Larøi F, Van der Linden M, DeFruyt F, van Os J, Aleman A: Associations between delusion proneness and personality structure in non-clinical participants: comparison between young and elderly samples. Psychopathology 2006;39:218–226.
Van Winkel R, Stefanis NC, Myin-Germeys I: Psychosocial stress and psychosis. A review of the neurobiological mechanisms and the evidence for gene-stress interaction. Schizophr Bull 2008;34:1095–1105.
Maric N, Krabbendam L, Vollebergh W, de Graaf R, van Os J: Sex differences in symptoms of psychosis in a non-selected, general population sample. Schizophr Res 2003;63:89–95.
Scott J, Welham J, Martin G, Bor W, Najman J, O’Callaghan M, Williams G, Aird R, McGrath J: Demographic correlates of psychotic-like experiences in young Australian adults. Acta Psychiatr Scand 2008;118:230–237.
López-Ilundain JM, Pérez-Nievas E, Otero M, Mata I: Peter’s delusions inventory in Spanish general population: internal reliability, factor structure and association with demographic variables (dimensionality of delusional ideation). Actas Esp Psiquiatr 2006;34:94–104.
Freeman D, Pugh K, Antley A, Slater M, Bebbington P, Gittins M, Dunn G, Kuipers E, Fowler D, Garety P: Virtual reality study of paranoid thinking in the general population. Br J Psychiatry 2008;192:258–263.
Freeman D, McManus S, Brugha T, Meltzer H, Jenkins R, Bebbington P: Concomitants of paranoia in the general population. Psychol Med 2010;24:1–14.
Lundberg P, Cantor-Graae E, Kabakyenga J, Rukundo G, Ostergren PO: Prevalence of delusional ideation in a district in southwestern Uganda. Schizophr Res 2004;71:27–34.
Yazdi AB, Bolhari J, Shah Mohammadi D: An epidemiological study of psychological disorders in a rural area (Meibod, Yazd) in Iran. Attitude Behav 1994;1:32–41.
Olsen LR, Mortensen EL, Bech P: The SCL-90 and SCL-90R version validated by items response models in a Danish community sample. Acta Psychiatr Scand 2004;110:225–229.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.