This issue contains one review, on predicting costs of mental health care. Other sets of papers examine various aspects of psychosis.

Background. Cost evaluation research in the mental health field is being increasingly recognized as a way to achieve a more effective deployment of scarce resources. However, there is a paucity of studies that seek to identify predictors of psychiatric service utilization and costs. This paper aims to critically review the published research in the field of psychiatric service utilization and costs, and discusses current methodological developments in this field.

Method. Sixteen studies were identified and are critically reviewed.

Results. No single variable alone can explain variations in costs between patients; instead, a range of different clinical and non-clinical variables provides a greater explanation of cost variations. Having a history of previous psychiatric service use is the most consistent predictor of higher psychiatric costs. Only one study considers indirect costs incurred by users, their families and friends and society as a whole, with the remaining 15 studies focusing on direct mental health care costs. There is a lack of studies that consider the future psychiatric service utilization and costs of care of children and older people. The cross-validation of predictive models is not yet routine, with only four of the studies including a cross-validation procedure.

Conclusions. The predictive approach in mental health cost evaluation has relevance for both mental health policy and practice. However, there is a paucity of studies that focus on children, older people and indirect costs. Furthermore, there remain a number of methodological challenges to address.

Background. Gender differences are commonly reported in schizophrenia research, especially with regard to age at onset. Few studies have reported the age- and gender-specific incidence of schizophrenia in people aged up to 71 years, and no studies have reported the cumulative incidence of schizophrenia in people aged up to 71 years.

Method. Two cohorts were established by linking data from the Danish Civil Registration System (DCRS) with data from the Danish Psychiatric Central Register (DPCR), which covers all incident cases of schizophrenia from 15 to 71 years. We estimated the gender- and age-specific incidence rates of schizophrenia for people aged up to 71 years. We also estimated the cumulative incidences.

Results. The incidence rates for males significantly exceeded those for females in the age range from 17 to 40 years. By their 72nd birthday, 1·59% of males and 1·17% of females had developed schizophrenia.

Conclusion. Male sex is a major risk factor for the development of schizophrenia.

Background. Urban birth, a risk factor for schizophrenia, is more frequent among second-generation immigrants. The aim of the current study was to determine whether the increased risk for schizophrenia found in second-generation immigrants is explained by the degree of urbanization of birthplace and/or factors related to parentage, such as geographic origin or history of residence abroad during upbringing.

Method. Using data from the Danish Civil Registration System (CRS), we established a population-based cohort of 2·0 million Danes (persons born in Denmark). Schizophrenia in cohort members was identified by cross-linkage with the Danish Psychiatric Central Register.

Results. The relative risk of developing schizophrenia was 1·93 [95% confidence interval (CI) 1·79–2·08] and 2·96 (95% CI 2·49–3·51) among persons with one or both parents foreign-born respectively compared to native Danes. Adjustment for urbanization of birthplace and parental characteristics reduced these risks slightly. However, urbanization had a lesser effect in second-generation immigrants than in Danes. History of residence abroad was a risk factor for schizophrenia, regardless of whether parents were foreign-born or native Danes.

Conclusion. The increased risk found in second-generation immigrants cannot be explained by urbanization or parental characteristics pertaining to age, mental illness, geographic origin or residence abroad during a child's upbringing.

Background. Numerous studies have reported high rates of psychosis in the Black Caribbean and Black African populations in the UK. However, few studies have investigated the role of specific risk factors in different ethnic groups. We sought to investigate the relationship between long-term separation from, and death of, a parent before the age of 16 and risk of adult psychosis in different ethnic groups.

Method. All patients with a first episode of psychosis who made contact with psychiatric services in defined catchment areas in London and Nottingham, UK and a series of community controls were included in the AESOP (Aetiology and Ethnicity in Schizophrenia and Other Psychoses) study. Data relating to clinical and social variables, including parental separation and loss, were collected from patients and controls.

Results. Separation from, and death of, a parent before the age of 16 were both strongly associated with a two- to threefold increased risk of psychosis. The strength of these associations were similar for White British and Black Caribbean (but not Black African) subjects. Separation from (but not death of) a parent was more common among Black Caribbean controls than White British controls.

Conclusions. Early separation may have a greater impact in the Black Caribbean population, because it is more common, and may contribute to the excess of psychosis in this population.

Background. The cause of increased schizophrenia rates among immigrants in Europe is unknown. This study explores psychotic features in persons aspiring and actively planning to emigrate, prior to their potential emigration.

Method. Potential future emigrants and controls in Kampala (Uganda) were screened for delusional ideation and manic symptoms, using the Peters et al. Delusions Inventory (PDI) and mania items from the Composite International Diagnostic Interview (CIDI).

Results. Aspirations regarding emigration were associated with increased delusional ideation compared with controls (p=0·01), whereas active plans regarding emigration were not. Neither aspiring nor actively planning to emigrate was associated with increased manic symptoms. Subjects with increased delusional ideation also had increased manic symptoms (p<0·001).

Conclusions. Although some aspects of delusional ideation might include thoughts concerning emigration, practical circumstances (e.g. visa requirements, travel costs) probably prevent emigration of the psychosis-prone in many settings.

Background. Research suggests that low-grade psychotic experiences in the general population are a common but transitory developmental phenomenon. Using two independent general population samples, the hypothesis was examined that common, non-clinical developmental expression of psychosis may become abnormally persistent when synergistically combined with developmental exposures that may impact on behavioural and neurotransmitter sensitization such as cannabis, trauma and urbanicity.

Method. The amount of synergism was estimated from the additive statistical interaction between baseline cannabis use, childhood trauma and urbanicity on the one hand, and baseline psychotic experiences on the other, in predicting 3-year follow-up psychotic experiences, using data from two large, longitudinal, random population samples from the Netherlands [The Netherlands Mental Health Survey and Incidence Study (NEMESIS)] and Germany [The Early Developmental Stages of Psychopathology (EDSP) study].

Results. The 3-year persistence rates of psychotic experiences were low at 26% in NEMESIS and 31% in EDSP. However, persistence rates were progressively higher with greater baseline number of environmental exposures in predicting follow-up psychotic experiences (χ2=6·9, df=1, p=0·009 in NEMESIS and χ2=4·2, df=1, p=0·04 in EDSP). Between 21% and 83% (NEMESIS) and 29% and 51% (EDSP) of the subjects exposed to both environmental exposures and psychotic experiences at baseline had persistence of psychotic experiences at follow-up because of the synergistic action of the two factors.

Conclusion. The findings suggest that environmental risks for psychosis act additively, and that the level of environmental risk combines synergistically with non-clinical developmental expression of psychosis to cause abnormal persistence and, eventually, need for care.

Background. There has been a long-standing debate as to whether postpartum psychoses are distinct from other psychoses. While the outcomes of postpartum psychosis are in general thought to be good, the disorder is linked to a high rate of suicide.

Method. We have utilized a database of 3872 admissions to the North Wales Asylum during the period 1875–1924 to extract data on the prevalence, course and clinical features of postpartum psychoses during this period. We have collected first admissions for postpartum psychosis between 1994 and 2005 in North West Wales to establish a current incidence rate for the disorder.

Results. The incidence of psychoses with a first onset in the postpartum period in North West Wales has fallen in the modern period, while the incidence of postpartum psychoses in women with a pre-existing mental illness remains the same. Some features of the clinical picture and course of postpartum psychoses differ from other psychoses, but may be gender rather than disorder linked.

Conclusions. These findings suggest that psychoses with their first onset in the postpartum period may be vanishing. If replicated, this would support claims that these disorders are distinct from other disorders. Alternately, if regarded as affective disorders, establishing the basis for the apparent decline in frequency of these disorders may have implications for other affective disorders.

Background. Poor clinician-rated parenting outcome and observed interactive deficits in mothers with schizophrenia admitted to a psychiatric mother and baby unit (MBU) reflect continuing concerns over the parenting capacity of this group. However, little is known about whether interaction deficits are accounted for by severity of illness or adverse social circumstances typically experienced by these mothers.

Method. Thirty-eight women with severe perinatal illness (schizophrenia n=13; affective disorders n=25) and their infants were observed in play interaction a week prior to MBU discharge. Clinical and sociodemographic data were also obtained.

Results. Mothers with schizophrenia and their infants were rated to have poorer interactive behaviour than the affective disorders group. Infant avoidance of the mother was associated with a lack of maternal sensitivity and responsiveness. The deficits in mother–infant interaction found in the schizophrenia group could not be accounted for by our measures of illness severity or factors relating to adverse social circumstances.

Conclusions. The results replicate and extend previous findings showing poor interactive behaviours in mothers with schizophrenia, their infants, and in the dyad, in a range of areas following clinical recovery. The findings suggest that factors other than illness duration, dose of medication, marital status and occupational status are explanatory for the interactive deficits associated with maternal schizophrenia. Parenting interventions that aim to improve maternal sensitivity need to be developed specifically for this group.

Background. Aggressive behaviour is increased among those with schizophrenia but less is known about those with affective psychoses. Similarly, little is known about aggressive behaviour occurring at the onset of illness.

Method. The main reasons for presentation to services were examined among those recruited to a UK-based first episode psychosis study. The proportion of individuals presenting with aggressive behaviour was determined and these individuals were compared to those who were not aggressive on a range of variables including sociodemographic, clinical, criminal history, service contact, and symptom characteristics. Among the aggressive group, those who were physically violent were distinguished from those who were not violent but who were still perceived to present a risk of violence to others.

Results. Almost 40% (n=194) of the sample were aggressive at first contact with services; approximately half of these were physically violent (n=103). Younger age, African-Caribbean ethnicity and a history of previous violent offending were independently associated with aggression. Aggressive behaviour was associated with a diagnosis of mania and individual manic symptoms were also associated with aggression both for the whole sample and for those with schizophrenia. Factors differentiating violent from non-violent aggressive patients included male gender, lower social class and past violent offending.

Conclusions. Aggressive behaviour is not an uncommon feature in those presenting with first episode psychosis. Sociodemographic and past offending factors are associated with aggression and further differentiate those presenting with more serious violence. A diagnosis of mania and the presence of manic symptoms are associated with aggression.

Background. In this study we examined patients' false memory, that is memory for a non-presented event, to search for a further source of converging evidence for the impairment of semantic memory in individuals with schizophrenia. In two experiments we compared the pattern of false memory created by the Deese–Roediger–McDermott (DRM) paradigm between individuals with schizophrenia and those of a normal control group.

Method. Experiment 1 tested participants on both recall and recognition of lists of semantically related words. Experiment 2 adopted the meaning recognition test, in addition to the standard recognition test, to assess the participants' gist memory.

Results. Individuals with schizophrenia performed worse than normal controls on both recall and recognition of studied words. The schizophrenia patients had higher rates of false recall and false recognition for semantically unrelated words than did the normal controls, suggesting an abnormal pattern of semantic activation in the former group. More importantly, no differences were found between the two groups with regard to false recall and false recognition of semantically related words. When the participants were tested for meaning recognition, however, the schizophrenia patients gave fewer ‘old’ responses to non-studied semantically related words than did the control group, indicating an impaired gist memory in schizophrenia patients.

Conclusions. When asked to consciously retrieve word lists, individuals with schizophrenia showed impairment not only in item-specific memory but also in gist memory. The pattern of results is consistent with the storage deficit view of semantic memory in schizophrenia.

Background. Current cognitive models of positive symptoms of psychosis suggest a mechanism of defective self-monitoring that may be relevant for (i) expression of psychosis at the clinical and subclinical level and (ii) transmission of risk for psychosis.

Method. The study included 41 patients with psychosis, 39 non-psychotic first-degree relatives, 39 subjects from the general population with a high level of positive psychotic experiences, and 52 healthy controls with an average level of positive psychotic experiences. All subjects performed a speech attribution task in which single adjectives with a complimentary or derogatory meaning were presented to them on a computer screen; subjects had to read aloud and determine the source (self/other/uncertain) of the words they heard. In some of the trials, participants’ speech was distorted, in others they heard someone else's voice (alien feedback condition) that could also be distorted.

Results. No large or significant differences in errors in the speech attribution task were found between the four groups in any of the conditions.

Conclusions. Contrary to previous work using this paradigm, this study found no evidence that either expression of psychosis or risk for psychosis was associated with impairment in self-monitoring.

Background. Previous studies report skin conductance (SC) abnormalities in both patients with schizophrenia and psychosis-prone individuals. However, no studies have assessed SC abnormalities in relation to specific psychotic and emotional symptoms. The aim of the present study was to examine the relationship between SC orienting response and hallucination proneness, delusional ideation, anxiety and self-focused attention in non-clinical individuals.

Method. Forty-three participants were recruited and divided into two groups depending upon the SC habituation profile. Normal habituators (n=28) and slow habituators (n=15) were compared on measures of psychosis proneness, anxiety and self-focused attention.

Results. Slow habituators had significantly higher levels of delusional ideation and hallucination proneness than the normal habituators. SC habituation scores were particularly associated with the conviction of delusional ideas. Levels of anxiety or self-focused attention did not differ significantly between the groups.

Conclusions. The study provides evidence of ‘aetiological continuity’. Common mechanisms may contribute to psychotic experiences in non-clinical and clinical samples, consistent with the notion of a psychosis continuum.

Background. Previous research has confirmed the presence of increased motor overflow in schizophrenia. There are essentially two theories regarding the cortical origins of overflow. Recent research suggests that both may be correct, and that the cortical origin of overflow is highly dependent upon the population in which it presents. Motor overflow, due to an abnormally active ipsilateral corticospinal tract, may indicate a potentially severe brain abnormality arising in early development. In contrast, bilaterally active corticospinal tracts accounting for overflow probably represent a naturally occurring response during fatiguing contractions.

Method. The cortical origins of motor overflow in 20 participants with schizophrenia and 20 normal controls were investigated through the use of a number of transcranial magnetic stimulation (TMS) protocols.

Results. Each of the experimental protocols employed independently supported the contention that overflow was originating in the hemisphere contralateral to the involuntary movement.

Conclusions. Results indicated that the origins of overflow in schizophrenia are the same as those seen in the normal control group, i.e. motor overflow seems to be due to the presence of bilaterally active corticospinal tracts. Potential explanations for greater motor overflow seen in schizophrenia are discussed.

Background. Deficits in a patient's ‘theory of mind’ (TOM) have been proposed to lead to psychosis. However, it remains unclear whether TOM deficits constitute a trait- or a state-related deficit and whether they respond to antipsychotic treatment, and also whether the change in TOM and change in psychosis are associated.

Method. In the cross-sectional component of this study, 71 patients with psychotic disorders were included and TOM ability was measured using a hinting task in which subjects had to infer real intentions behind indirect speech. In the longitudinal study, a different cohort of 17 drug-free patients were included wherein they received antipsychotic treatment for 6 weeks and the effect on psychotic symptoms and TOM was measured every 2 weeks. Associations between TOM and psychopathology were assessed and a mixed effects model was used to investigate the rate of change over time.

Results. Positive and Negative Syndrome Scale (PANSS) total scores were significantly associated with TOM scores. The hinting task was not associated with positive symptoms but was significantly associated with negative and general symptoms. The longitudinal arm of the study showed that both PANSS positive scores and TOM improved after medication was started, particularly during the first 2 weeks of antipsychotic treatment, but these changes were not associated. The TOM response at 2 weeks of antipsychotic treatment reached similar values to those obtained in the cross-sectional sample.

Conclusions. Although TOM and psychotic symptoms are related to each other, antipsychotic treatment impacts each independently, suggesting a dissimilar cognitive or neurobiological substrate for the two.