Personality disorder (PD) in psychosis is poorly studied. As PD can affect outcome in mental disorders, it is important to understand its prevalence in order to plan services, understand prognosis more fully and maximize management options.

Literature searching revealed 3972 potential papers. Twenty papers including 6345 patients were included in the final analysis. There was great variation in prevalence and multilevel modelling was used to identify possible reasons for this heterogeneity.

The prevalence of PD varied from 4.5% to 100%. Multilevel analysis suggested country of study, study type, the instruments used to diagnose PD and patient care correlated with the prevalence data explaining the study level heterogeneity, with 34.2, 33.4, 17.0 and 4.5% by each variable respectively. Personality studies in Canada and Sweden reported lower PD prevalence, whereas in Spain it was higher than the multinational study. Compared with randomized controlled trials, case-control studies reported lower prevalence [odds ratio (OR)=0.35, 95% confidence interval (CI) 0.15–0.79] and observational studies higher prevalence (OR 70.5, 95% CI 8.5–583). Primary-care patients were less likely to be diagnosed (OR 0.02, 95% CI 0–0.19) than hospital patients, and out-patients had higher prevalence (OR 12.5, 95% CI 1.77–88.6).

The reported prevalence of PD in schizophrenia varies significantly. Statistical modelling suggests care, country, study type and diagnostic tools for PD all bias prevalence rates. The number of papers reaching the inclusion criteria, the relative paucity of information and the difficulties in developing an accurate statistical model limited interpretation from the study.

Social capital has been considered aetiologically important in schizophrenia but the empirical evidence to support this hypothesis is absent. We tested whether social capital, measured at the neighbourhood level, was associated with the incidence of schizophrenia (ICD-10 F20).

We administered a cross-sectional questionnaire on social capital to 5% of the adult population in 33 neighbourhoods (wards) in South London (n=16 459). The questionnaire contained items relating to two social capital constructs: social cohesion and trust (SC&T) and social disorganization (SocD). Schizophrenia incidence rates, estimated using data from the Aetiology and Ethnicity in Schizophrenia and Other Psychoses (AESOP) study, provided the outcome. We used multi-level Poisson regression to test our hypothesis while controlling for individual- and neighbourhood-level characteristics.

We identified 148 cases during 565 576 person-years at-risk. Twenty-six per cent of the variation in incidence rates was attributable to neighbourhood-level characteristics. Response from the social capital survey was 25.7%. The association between SC&T and schizophrenia was U-shaped. Compared with neighbourhoods with medial levels of SC&T, incidence rates were significantly higher in neighbourhoods with low [incidence rates ratio (IRR) 2.0, 95% confidence interval (CI) 1.2–3.3] and high (IRR 2.5, 95% CI 1.3–4.8) levels of SC&T, independent of age, sex, ethnicity, ethnic density, ethnic fragmentation and socio-economic deprivation.

Neighbourhood variation in SC&T was non-linearly associated with the incidence of schizophrenia within an urban area. Neighbourhoods with low SC&T may fail to mediate social stress whereas high SC&T neighbourhoods may have greater informal social control or may increase the risk of schizophrenia for residents excluded from accessing available social capital.

Psychotic disorders are more common in people from ethnic minorities. If psychosis exists as a continuous phenotype, ethnic disparities in psychotic disorder will be accompanied by similar ethnic disparities in the rate of psychotic symptoms. This study examined ethnic disparities in self-reported hallucinations in a population sample of young adults.

A cross-sectional population survey (n=2258) was carried out in the south-west Netherlands. Seven ethnic groups were delineated: Dutch natives, Turks, Moroccans, Surinamese/Antilleans, Indonesians, other non-Western immigrants (mostly from Africa or Asia) and Western immigrants (mostly from Western Europe). Self-reported auditory and visual hallucinations were assessed with the Adult Self-Report (ASR). Indicators of social adversity included social difficulties and a significant drop in financial resources.

Compared to Dutch natives, Turkish females [odds ratio (OR) 13.48, 95% confidence interval (CI) 5.97–30.42], Moroccan males (OR 8.36, 95% CI 3.29–21.22), Surinamese/Antilleans (OR 2.19, 95% CI 1.05–4.58), Indonesians (OR 4.15, 95% CI 1.69–10.19) and other non-Western immigrants (OR 3.57, 95% CI 1.62–7.85) were more likely to report hallucinations, whereas Western immigrants, Turkish males and Moroccan females did not differ from their Dutch counterparts. When adjusting for social adversity, the ORs for self-reported hallucinations among the non-Western immigrant groups showed considerable reductions of 28% to 52%.

In a general population sample, several non-Western immigrant groups reported hallucinations more often than Dutch natives, which is consistent with the higher incidence of psychotic disorders in most of these groups. The associations between ethnicity and hallucinations diminished after adjustment for social adversity, which supports the view that adverse social experiences contribute to the higher rate of psychosis among migrants.

The incidence of schizophrenia and the prevalence of psychotic symptoms in the general adult population are elevated in migrant and ethnic minority groups relative to host populations. These increases are particularly prominent among African-Caribbean migrants to the UK. This study examined the associations of ethnicity and migrant status with a triad of putative antecedents of schizophrenia in a UK community sample of children aged 9–12 years. The antecedent triad comprised: (i) psychotic-like experiences; (ii) a speech and/or motor developmental delay or abnormality; and (iii) a social, emotional or behavioural problem.

Children (n=595) and their primary caregivers, recruited via schools and general practitioners in southeast London, completed questionnaires. Four indices of risk were examined for associations with ethnicity and migrant status: (i) certain experience of at least one psychotic-like experience; (ii) severity of psychotic-like experiences (total psychotic-like experience score); (iii) experience of the antecedent triad; and (iv) severity of antecedent triad experiences (triad score).

African-Caribbean children, as compared to white British children, experienced greater risk on all four indices. There were trends for South Asian and Oriental children to present lowered risk on several indices, relative to white British children. Migration status was unrelated to any risk index.

Prevalence of the putative antecedents of schizophrenia is greater among children of African-Caribbean origin living in the UK than among white British children. This parallels the increased incidence of schizophrenia and elevated prevalence of psychotic symptoms among adults of African-Caribbean origin.

Being a small and culturally different minority, or having a different appearance, has been invoked to account for the increased prevalence of psychotic disorders among immigrants. The majority of the Jewish Israeli population are first- or second-generation immigrants from Europe, North Africa or Asia, and during the late 1980s and 1990s, 885 000 persons immigrated to Israel from the former Soviet Union and 43 000 immigrated from Ethiopia. These Ethiopian immigrants came from a very different culture compared to the rest of the population, and have a distinct appearance. To further understand the association between immigration and schizophrenia, we compared risk for later schizophrenia between adolescents who immigrated from Ethiopia with risk among the other immigrant groups, and with native-born Israelis.

Of 661 792 adolescents consecutively screened by the Israeli Draft Board, 557 154 were native-born Israelis and 104 638 were immigrants. Hospitalization for schizophrenia was ascertained using a National Psychiatric Hospitalization Case Registry. All analyses controlled for socio-economic status (SES).

Risk for schizophrenia was increased among both first- [hazard ratio (HR) 1.62, 95% confidence interval (CI) 1.18–2.22] and second-generation immigrants [HR 1.41, 95% CI 1.01–1.95 (one immigrant parent) and HR 1.49, 95% CI 1.11–2.0 (two immigrant parents)]. When risk for schizophrenia was calculated for each immigrant group separately, immigrants from Ethiopia were at highest risk of later schizophrenia (HR 2.95, 95% CI 1.88–4.65).

This comparison between diverse groups of immigrants supports the notion that immigrants who differ in culture and appearance from the host population are at increased risk for schizophrenia.

In recent years a close association between anxiety and persecutory ideation has been established, contrary to the traditional division of neurosis and psychosis. Nonetheless, the two experiences are distinct. The aim of this study was to identify factors that distinguish the occurrence of social anxiety and paranoid thoughts in an experimental situation.

Two hundred non-clinical individuals broadly representative of the UK general population were assessed on a range of psychological factors, experienced a neutral virtual reality social environment, and then completed state measures of paranoia and social anxiety. Clustered bivariate logistic regressions were carried out, testing interactions between potential predictors and the type of reaction in virtual reality.

The strongest finding was that the presence of perceptual anomalies increased the risk of paranoid reactions but decreased the risk of social anxiety. Anxiety, depression, worry and interpersonal sensitivity all had similar associations with paranoia and social anxiety.

The study shows that social anxiety and persecutory ideation share many of the same predictive factors. Non-clinical paranoia may be a type of anxious fear. However, perceptual anomalies are a distinct predictor of paranoia. In the context of an individual feeling anxious, the occurrence of odd internal feelings in social situations may lead to delusional ideas through a sense of ‘things not seeming right’. The study illustrates the approach of focusing on experiences such as paranoid thinking rather than diagnoses such as schizophrenia.

There is abundant evidence that schizophrenia is associated with cognitive deficits in childhood. However, previous studies investigating school performance have been inconclusive. Furthermore, there are several biological and social factors that could confound the association. We investigated whether school performance at age 16 is associated with risk of adult schizophrenia and other psychoses in a large national cohort, while controlling for multiple confounders.

Using a national sample of 907 011 individuals born in Sweden between 1973 and 1983, we used Cox regression to assess whether scholastic achievement at age 15–16 predicted hospital admission for psychosis between ages 17 and 31, adjusting for potential confounders.

Poor school performance was associated with increased rates of schizophrenia [hazard ratio (HR) 3.9, 95% confidence interval (CI) 2.8–5.3], schizo-affective disorder (HR 4.2, 95% CI 1.9–9.1) and other psychoses (HR 3.0, 95% CI 2.3–4.0). Receiving the lowest (E) grade was significantly associated with risk for schizophrenia and other psychoses in every school subject. There was no evidence of confounding by migrant status, low birthweight, hypoxia, parental education level or socio-economic group.

Poor school performance across all domains is strongly associated with risk for schizophrenia and other psychoses.

The outcome of schizophrenia appears to be more favourable than once thought. However, methodological issues, including the reliance on diagnosis at first presentation have limited the validity of outcome studies to date.

We conducted a first-episode follow-up study of 97 patients with DSM-IV schizophrenia over the first 4 years of illness. First presentation and follow-up assessments were compared using paired t tests and a forced-entry regression analysis was used to determine prognostic variables.

There were significant improvements in positive and negative symptoms and global assessment of functioning between first presentation and follow-up. At first presentation, fewer negative symptoms (t=−3.40, p<0.01), more years spent in education (t=3.25, p<0.01), and a shorter duration of untreated psychosis (DUP) (t=−2.77, p<0.01) significantly predicted a better outcome at follow-up.

The outcome of schizophrenia may not be as pessimistic as once thought and most patients did not display a downward deteriorating course of illness. This study supports the relationship between DUP and outcome beyond the early stages of illness.

Few studies have examined the underlying factor structure of signs and symptoms occurring before the first psychotic episode. Our objective was to determine whether factors derived from early signs and symptoms are differentially associated with non-affective versus affective psychosis.

A principal components factor analysis was performed on early signs and symptoms reported by 128 individuals with first-episode psychosis. Factor scores were examined for their associations with duration of untreated illness, drug abuse prior to onset of psychosis, and diagnosis (schizophrenia versus affective psychosis).

Of the 27 early signs and symptoms reported by patients, depression and anxiety were the most frequent. Five factors were identified based on these early signs and symptoms: depression, disorganization/mania, positive symptoms, negative symptoms and social withdrawal. Longer duration of untreated illness was associated with higher levels of depression and social withdrawal. Individuals with a history of drug abuse prior to the onset of psychosis scored higher on pre-psychotic depression and negative symptoms. The two mood-related factors, depression and disorganization/mania, distinguished the eventual first-episode diagnosis of affective psychosis from schizophrenia. Individuals with affective psychosis were also more likely to have a ‘mood-related’ sign and symptom as their first psychiatric change than individuals later diagnosed with schizophrenia.

Factors derived from early signs and symptoms reported by a full diagnostic spectrum sample of psychosis can have implications for future diagnostic trajectories. The findings are a step forward in the process of understanding and characterizing clinically important phenomena to be observed prior to the onset of psychosis.

The association between the duration of untreated psychosis (DUP) and outcome of schizophrenia may be confounded by other factors such as poor pre-morbid adjustment. The aim of the present study was to examine the independent contributions of DUP and of pre-morbid adjustment to the clinical and social outcomes of schizophrenia.

A longitudinal, prospective, 2-year follow-up study of 423 patients with first-episode schizophrenia-spectrum psychosis was conducted. Patients were comprehensively assessed at entry, 1-year and 2-year follow-up. At entry, DUP was measured by IRAOS (an instrument for the assessment of onset and early course of schizophrenia) and pre-morbid adjustment was measured by the Pre-morbid Adjustment Scale (PAS) as ‘pre-morbid social adaptation’ and ‘pre-morbid school adaptation’. Outcome measures included the Scale for the Assessment of Positive Symptoms (SAPS), the Scale for the Assessment of Negative Symptoms (SANS), the Social Network Schedule and social information. Multiple linear regression models were used for data analysis.

The median DUP was 48 weeks, which is long compared to other studies. Longer DUP was independently associated with more psychotic symptoms at entry, 1-year and 2-year follow-up. Poorer pre-morbid social adaptation was independently associated with more negative symptoms and smaller social network at entry and 1-year follow-up. Poorer pre-morbid school adaptation was independently associated with poor vocational outcome at 1-year and 2-year follow-up.

Longer DUP is associated with poorer 2-year outcome of psychosis in schizophrenia-spectrum disorders, when pre-morbid functioning and other prognostic factors are controlled for. Impaired pre-morbid development is independently associated with more negative symptoms and poorer social outcome.

Determining how patients distinguish auditory verbal hallucinations (AVHs) from their everyday thoughts may shed light on neurocognitive processes leading to these symptoms.

Fifty patients reporting active AVHs (‘voices’) with a diagnosis of schizophrenia or schizo-affective disorder were surveyed using a structured questionnaire. Data were collected to determine: (a) the degree to which patients distinguished voices from their own thoughts; (b) the degree to which their thoughts had verbal form; and (c) the experiential basis for identifying experiences as voices versus their own verbal thoughts. Six characteristics of acoustic/verbal images were considered: (1) non-self speaking voice, (2) loudness, (3) clarity, (4) verbal content, (5) repetition of verbal content, and (6) sense of control.

Four subjects were eliminated from the analysis because they reported absent verbal thought or a total inability to differentiate their own verbal thoughts from voices. For the remaining 46 patients, verbal content and sense of control were rated as most salient in distinguishing voices from everyday thoughts. With regard to sensory/perceptual features, identification of speaking voice as non-self was more important in differentiating voices from thought than either loudness or clarity of sound images.

Most patients with schizophrenia and persistent AVHs clearly distinguish these experiences from their everyday thoughts. An adequate mechanistic model of AVHs should account for distinctive content, recognizable non-self speaking voices, and diminished sense of control relative to ordinary thought. Loudness and clarity of sound images appear to be of secondary importance in demarcating these hallucination experiences.

It has recently been suggested that auditory hallucinations are the result of a criterion shift when deciding whether or not a meaningful signal has emerged. The approach proposes that a liberal criterion may result in increased false-positive identifications, without additional perceptual deficit. To test this hypothesis, we devised a speech discrimination task and used signal detection theory (SDT) to investigate the underlying cognitive mechanisms.

Schizophrenia patients with and without auditory hallucinations and a healthy control group completed a speech discrimination task. They had to decide whether a particular spoken word was identical to a previously presented speech stimulus, embedded in noise. SDT was used on the accuracy data to calculate a measure of perceptual sensitivity (Az) and a measure of response bias (β). Thresholds for the perception of simple tones were determined.

Compared to healthy controls, perceptual thresholds were higher and perceptual sensitivity in the speech task was lower in both patient groups. However, hallucinating patients showed increased sensitivity to speech stimuli compared to non-hallucinating patients. In addition, we found some evidence of a positive response bias in hallucinating patients, indicating a tendency to readily accept that a certain stimulus had been presented.

Within the context of schizophrenia, patients with auditory hallucinations show enhanced sensitivity to speech stimuli, combined with a liberal criterion for deciding that a perceived event is an actual stimulus.

Functional imaging studies using working memory tasks have documented both prefrontal cortex (PFC) hypo- and hyperactivation in schizophrenia. However, these studies have often failed to consider the potential role of task-related deactivation.

Thirty-two patients with chronic schizophrenia and 32 age- and sex-matched normal controls underwent functional magnetic resonance imaging (fMRI) scanning while performing baseline, 1-back and 2-back versions of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups.

The controls showed activation in the expected frontal regions. There were also clusters of deactivation, particularly in the anterior cingulate/ventromedial PFC and the posterior cingulate cortex/precuneus. Compared to the controls, the schizophrenic patients showed reduced activation in the right dorsolateral prefrontal cortex (DLPFC) and other frontal areas. There was also an area in the anterior cingulate/ventromedial PFC where the patients showed apparently greater activation than the controls. This represented a failure of deactivation in the schizophrenic patients. Failure to activate was a function of the patients' impaired performance on the n-back task, whereas the failure to deactivate was less performance dependent.

Patients with schizophrenia show both failure to activate and failure to deactivate during performance of a working memory task. The area of failure of deactivation is in the anterior prefrontal/anterior cingulate cortex and corresponds to one of the two midline components of the ‘default mode network’ implicated in functions related to maintaining one's sense of self.

A potential association between schizophrenia and osteoporosis or osteopenia has recently been reported. Various factors affect bone mineral density (BMD) such as polydipsia, nicotine, alcohol abuse, lack of physical activity, an unbalanced diet, a lack of ultraviolet exposure and/or vitamin D. In addition, decreased BMD in women with schizophrenia has been attributed to drug-induced hyperprolactinaemia and/or secondary hypogonadism. This study was undertaken because empirical evidence from larger patient cohorts is limited and the data are still controversial.

Seventy-two premenopausal, regularly menstruating women suffering from schizophrenia and 71 age- and sex-matched healthy controls were included in the study. Biochemical markers of bone turnover (serum osteocalcin, urinary pyridinium crosslinks), parathyroid hormone and 25-hydroxyvitamin D were measured. BMD at the femoral neck and lumbar spine was determined by dual-energy X-ray absorptiometry in a subgroup of 59 patients. In addition, 17β-oestradiol, prolactin, testosterone, gonadotrophins and dehydroepiandrosterone sulfate were measured.

Compared with healthy controls, both markers of formation and resorption were increased in women with schizophrenia. However, in the subgroup of 59 patients, BMD was within the normal range. In women suffering from schizophrenia, testosterone levels were higher than in controls, and serum oestradiol levels were lower compared with the normal range.

Despite significantly increased bone turnover, we conclude that premenopausal and regularly menstruating women suffering from schizophrenia have normal spine and hip BMD. This may be due to the opposite effects of the various parameters influencing bone metabolism, especially of the gonadal hormones, and due to an intact coupling mechanism.

Previous studies suggest that offspring of mothers with psychotic disorders have an almost two-fold higher mortality risk from birth until early adulthood. We investigated predictors of mortality from late adolescence until middle age in offspring of mothers with psychotic disorders.

The Helsinki High-Risk Study follows up offspring (n=337) of women treated for schizophrenia spectrum disorders in mental hospitals in Helsinki before 1975. Factors related to mortality up to 2005 among offspring of these mothers was investigated with a survival model. Hazard rate ratios (HRR) were calculated using sex, diagnosis of psychotic disorder, childhood socio-economic status, maternal diagnosis, and maternal suicide attempts and aggressive symptoms as explanatory variables. The effect of family was investigated by including a frailty term in the model. We also compared mortality between the high-risk group and the Finnish general population.

Within the high-risk group, females had lower all-cause mortality (HRR 0.43, p=0.05) and mortality from unnatural causes (HRR 0.24, p=0.03) than males. Having themselves been diagnosed with a psychotic disorder was associated with higher mortality from unnatural causes (HRR 4.76, p=0.01), while maternal suicide attempts were associated with higher suicide mortality (HRR 8.64, p=0.03). Mortality in the high-risk group was over two-fold higher (HRR 2.44, p<0.0001) than in the general population, and remained significantly higher when high-risk offspring who later developed psychotic disorders were excluded from the study sample (HRR 2.30, p<0.0001).

Offspring of mothers with psychotic disorder are at increased risk of several adverse outcomes, including premature death.