The development of the Early Intervention in Psychosis (EIP) outpatient unit of Eginition University Hospital into an EIP Network

Over the past 25 years, in the field of psychosis there is an increased interest in early detection of symptoms and treatment provision for people who are either at Ultra High Risk (UHR) of developing psychosis or with First Episode Psychosis (FEP). Extensive research has proved, that by engaging quickly into treatment and addressing the needs of each case individually, clinical outcomes could be improved substantially. The above evidence-based argument has resulted in the establishment of specialized Early Intervention in Psychosis (EIP) services worldwide. Eginition University Hospital (EUH) in Athens has been providing care for Early Psychosis through a specialized outpatient EIP service since 2012, which receives all early psychosis cases. Initially clinical focus was mainly directed towards UHR cases, since EUH had long been providing standard care for FEP. However, over the last 4 years, the EIP Unit has evolved incrementally into a network of directly linked services, involving the EIP outpatient service, an Inpatient Unit for prompt hospitalization and a Day Clinic for partial hospitalization, to address acute treatment, follow-up and recovery/relapse prevention phases. Diagnostic evaluation is made through specialized instruments along with the typical psychiatric interview. The therapeutic approach follows the international guidelines for EIP, namely symptom-based and phase-specific treatment, which includes supportive counselling, coping strategies and psychoeducation both for subjects and family members, as well as pharmacotherapy when needed and preferably in low doses. Regarding our results, in the first 3 years (3/2012-3/2015) the EIP unit received 26 (60%) UHR subjects and 17 (40%) FEP patients. Over the last 4 years (3/2015-3/2019) the referrals rose to 167 with 35 (21%) UHR and 132 (79%) FEP cases. All of the UHR subjects were from the outset followed by the specialized outpatient EIP service for up to 3 years. As to the FEP patients, seventy-seven (60%) were acutely hospitalized for less than a month, and 10 (8%) attended the Day Clinic for 6 - 12 months, before being referred to the outpatient service. Concluding, the development of the EIP network of specialized services has cohesively enabled a broader therapeutic framework, shifting the clinical focus towards FEP, although UHR subjects are still being assessed systematically. However, there is still considerable work to be done, in order to enhance the full potential of all units and promote the interconnection with potential community settings.

[A proposal for the implementation of Early Intervention in Psychosis (EIP) services in Greece: If not now, when?]

The disorders of the psychosis spectrum, with the most severe being schizophrenia, are prevalent and have a great impact on the patients' quality of life. The purpose of this article is to highlight the need for a novel national strategic approach to the management of psychotic disorders in accordance with the international principles of early intervention. Even though outpatient treatment is considered adequate, there is an urgent need to adopt an early and more comprehensive and effective intervention strategy for young patients with psychosis and their families whose clinical and personal needs are clearly not met by the existing infrastructure of our mental health services. This can be accomplished by the legislation and implementation within the national health system of EIP services which on the one hand actively engage community organizations with the purpose of early identification of cases, reduction of the duration of untreated psychosis and on the other, offer assertive community-based support and treatment, based on a multi-disciplinary community team model. The effectiveness of early intervention in psychosis is supported by evidence provided by 9 international RCTs. The results of these programs indicate a superior effect in indexes of quality of life, retention in treatment, psychopathology, judicious use of medication and return to work/school as well as the patient's effective recovery. International experience (Denmark, Norway, Australia, UK, USA, Canada and Italy) and the corresponding prevention programs emphasize the effectiveness of EIP services and thus the patients' reintegration. However, in contrast to Northern European countries, Southern European countries have not yet incorporated EIP services in their national health system. From a financial perspective, EIP services seem to be cost-effective for the national health system, since the economic burden is compensated in the long term through their qualitative benefits. In Greece, specialized services for those young afflicted for the first time by the most serious of mental disorders are non-existent and no local information exists for the patient's outcome and social integration after a first psychotic-episode nor for the financial burden, placed on mental health services. Overall, the implementation of EIP services is expected to have long-term benefits for our country's National Health System as well as for the patients and their families.

Shared variance of oculomotor phenotypes in a large sample of healthy young men

This study used canonical correlation analysis to investigate patterns of shared variance between parameters measured in seven different occulomotor function tasks, namely the visually guided saccade task, the antisaccade task, the closed-loop smooth-pursuit task, the open-loop smooth-pursuit task, and three active visual fixation tasks. These tasks were performed by 2130 young army recruits. Only a small percentage (1-10%) of shared variance existed between sets of parameters for all oculomotor function tasks measured. The most correlated tasks were the visually guided saccade and the antisaccade. The first common factor correlated with speed of performance between these tasks (latency), while the second and third correlated with accuracy of performance. Better performance in active visual fixation tasks correlated with better performance accuracy (lower error rate) and increased speed (lower latency) in the antisaccade and saccade tasks as well as better performance in the closed-loop smooth-pursuit task (increase in gain and decrease in the rate of unwanted saccades during pursuit). Better performance in the closed-loop smooth-pursuit task (increased gain and decreased number of unwanted saccades) also correlated with increased accuracy and increased speed of performing saccades and antisaccades. Finally, the open-loop fixation task had no correlation with all other oculomotor tasks except for a very weak negative correlation with the closed-loop pursuit task where better performance (increased gain) in one correlated with worse performance (decreased gain) in the other. The results of this analysis showed that a small percentage of variance is shared among different oculomotor function tasks. The structure of this shared variance could be used to derive common oculomotor function indices to study their relation to genetic and other sources of inter-subject variation.

Steinberg and Durell (1968) revisited: increased rates of First Episode Psychosis following military induction in Greek Army Recruits

Since the seminal study of Steinbeck and Durell (1968), few epidemiological studies have attempted to replicate whether psychosocial stress precipitates the onset of a first psychotic episode. Our aim was to support or refute the finding of elevated psychosis incidence in the first month of army induction and to examine factors impacting the timing of onset. Data were collected from medical files of 186 army conscripts, hospitalized with a diagnosis of First Episode Psychosis (FEP) between 2005 and 2014 in the Psychiatric Military Hospital in Athens, Greece. FEP rates were at least 4.5 times higher in the first month of military service, compared with any other month. Earlier FEP onset was associated with rural environment at the time of birth, multiple drug use and service away from home. Psychosocial stress precipitates FEP, particularly in those exposed to other risk factors.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

This corrects the article DOI: 10.1038/mp.2016.244.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

The complex nature of human cognition has resulted in cognitive genomics lagging behind many other fields in terms of gene discovery using genome-wide association study (GWAS) methods. In an attempt to overcome these barriers, the current study utilized GWAS meta-analysis to examine the association of common genetic variation (~8M single-nucleotide polymorphisms (SNP) with minor allele frequency ⩾1%) to general cognitive function in a sample of 35 298 healthy individuals of European ancestry across 24 cohorts in the Cognitive Genomics Consortium (COGENT). In addition, we utilized individual SNP lookups and polygenic score analyses to identify genetic overlap with other relevant neurobehavioral phenotypes. Our primary GWAS meta-analysis identified two novel SNP loci (top SNPs: rs76114856 in the CENPO gene on chromosome 2 and rs6669072 near LOC105378853 on chromosome 1) associated with cognitive performance at the genome-wide significance level (P<5 × 10^-8). Gene-based analysis identified an additional three Bonferroni-corrected significant loci at chromosomes 17q21.31, 17p13.1 and 1p13.3. Altogether, common variation across the genome resulted in a conservatively estimated SNP heritability of 21.5% (s.e.=0.01%) for general cognitive function. Integration with prior GWAS of cognitive performance and educational attainment yielded several additional significant loci. Finally, we found robust polygenic correlations between cognitive performance and educational attainment, several psychiatric disorders, birth length/weight and smoking behavior, as well as a novel genetic association to the personality trait of openness. These data provide new insight into the genetics of neurocognitive function with relevance to understanding the pathophysiology of neuropsychiatric illness.

Early psychotic experiences: Interventions, problems and perspectives

Psychotic or psychotic-like experiences and symptoms may precede and be indicative of later psychosis emergence. DSM-5 has introduced Attenuated Psychosis Syndrome (APS) as a condition for further study, arguing for its clinical validity and the need for identifying sub- threshold psychotic states. Early psychosis intervention has an already established role in reducing the Duration of Untreated Psychosis (DUP), delaying psychosis onset and relieving Ultra High Risk (UHR) individuals from their presenting symptoms. Pharmacological and mainly psycho-therapeutical approaches are suggested for this purpose. Cognitive Behavior Therapy (CBT) seems to have clear evidence of favorable outcome concerning transition to psychosis rates, omega-3 fatty acids lower but promising evidence, while low-dose antipsychotic medication or antidepressant treatment may seem beneficial, but it remains unclear if the reported favorable effects persist in the long term and how long intervention in UHR subjects should be given for. Case management and close monitoring based on principles of social psychiatry are considered key elements for the management of UHR individuals. However, the blazing case about early psychosis concerns the accurate specification of the prodromal stage of psychosis, which may set the basis for meaningful and effective early intervention. Although psychometric tools have been developed and provide a common criteria-based recognition method, debate is alive and well regarding "false positive" cases, since most UHR subjects will not finally develop psychosis. Moreover, transition rates to psychosis have been declining over the years, leading to fierce criticism over the validity of the UHR/ APS state and legitimacy of its treatment. On this framework, ethical issues of stigmatizing through unnecessary diagnosing and antipsychotics' prescribing are matters of serious questioning. Clinical heterogeneity and high comorbidity are further implications of the UHR state. Current research emphasizes on improving validity of inclusion criteria and formulating personalised and clinical stage- based intervention strategies. In order to do that, early psychosis recognition and intervention services are established throughout the world, trying to contribute in research by applying clinical, cognitive or neuropsychological criteria. Nevertheless, in the majority of so far conducted studies, samples sizes are considered small and duration of follow-up short, which are limitations yet to overcome. Other scientific voices argue that the UHR state might represent a non-specific risk factor for psychiatric disorders in general and not necessarily for psychosis and tend to examine the UHR and early intervention idea under the prism of subthreshold or early mental distress state. Either way, recognizing and intervening early in emerging psychiatric states, especially in those with psychotic or psychotic-like symptomatology, share indisputable benefits under the broader concept of prevention, setting a strong scientific-clinical rationale for service provision to help-seeking people and the possibility of changing the course for those with vulnerability to psychotic illnesses.

Cognitive impairments and psychopathological parameters in patients of the schizophrenic spectrum

Cognitive impairment is a core feature of schizophrenia and it is considered by many researchers as one of the dimensional components of the disorder. Cognitive dysfunction occurs in 85% of schizophrenic patients and it is negatively associated with the outcome of the disorder, the psychosocial functioning of the patients, and non-compliance with treatment. Many different cognitive domains are impaired in schizophrenia, such as attention, memory, executive functions and speech. Nowadays, it is argued that apart from clinical heterogeneity of schizophrenia, there is probable heterogeneity in the accompanying neurocognitive dysfunction. Recent studies for cognitive dysfunction in schizophrenia employ computerized assessment batteries of cognitive tests, designed to assess specific cognitive impairments. Computerized cognitive testing permits for more detailed data collection (e.g. precise timing scores of responses), eliminates researcher's measurement errors and bias, assists the manipulation of data collected, and improves reliability of measurements through standardized data collection methods. The aims of the present study are: the comparison of cognitive performance of our sample of patients and that of healthy controls, on different specific cognitive tests, and the testing for possible association between patients' psychopathological symptoms and specific cognitive impairments, using the Cogtest computerized cognitive assessment battery. 71 male inpatients diagnosed with schizophrenia or other psychotic spectrum disorders (mean = 30.23 ± 7.71 years of age), admitted in a psychiatric unit of the First Department of Psychiatry, Athens University Medical School, Eginition Hospital (continuous admissions) were studied. Patients were excluded from the study if they suffered from severe neurological conditions, severe visual or hearing impairment, mental retardation, or if they abused alcohol or drugs. The patients' diagnoses were based on the semi-structured diagnostic interview "Diagnostic Interview for Psychosis" (DIP) and were clinically confirmed by two independent expert psychiatrists, according to the criteria of DSM-IVTM. Our healthy control group consisted of 20 healthy male participants (mean = 31.65 ± 5.90 years of age), who met the same inclusion criteria for the study as the patient group, as well as the same exclusion criteria from the study, having no history of psychiatric disorders. All statistical analyses were conducted using the statistical package SPSS.17. According to our results, healthy controls cognitively outperform our patient sample in all cognitive tests, with the differences between performances being statistically significant. Results concerning the association between psychotic symptoms and cognitive deficits of our patients indicated that hallucinations, highly organized delusions, persecutory delusions, agitation, catatonia and inappropriate affect did not associate with any subtype of cognitive deficit. Blunted affect associated significantly with response inhibition ("GoNoGo test", p = 0.007), and poor speech associated significantly with declarative memory of faces ("FMT test", p = 0.002). Moreover, psychomotor ability (non-dominant hand) associated significantly with generalized delusions ("TST test", p = 0.033), and with constricted affect ("TST test", p = 0.026). Furthermore, there was a tendency towards significance association between persecutory delusions and executive function ("CPT test", p = 0.053), inappropriate affect and declarative face memory ("FMT test", p = 0.056), and psychomotor ability and poor speech (p = 0.086).

Theory of Mind as a potential trait marker of schizophrenia: a family study

INTRODUCTION

Although there is some evidence that Theory of Mind (ToM) deficits may be trait markers of schizophrenia it is not clear yet if ToM deficits are primary deficits, that is, to be independent of deficits in general intellectual abilities and executive function. The aim was to examine if ToM deficits may be trait markers of the illness and the effect of cognitive inhibition, general intellectual abilities and depression on ToM abilities of patients with schizophrenia and their unaffected parents.

METHODS

We assessed ToM abilities (first-order and second-order ToM stories, The Revised Eyes Test), cognitive inhibition (Stroop Task), general intellectual ability (Standard Progressive Matrices Test Plus) in patients with schizophrenia (N=21) and their unaffected fathers (N=21) and mothers (N=21) in comparison with healthy control families (healthy control males, N=21, healthy control fathers, N=21, healthy control mothers, N=21)

RESULTS

Patients showed deficits in first-order ToM tasks but some of these deficits were mediated by general intellectual abilities. Impairments in cognitive inhibition mediated only patients' performance in The Revised Eyes Test. Patients showed deficits in second-order ToM stories independently of deficits in general intellectual abilities and cognitive inhibition. Unaffected parents did not show deficits in first-order ToM tasks, whereas they showed deficits in second-order ToM stories. However, the deficits that unaffected parents showed in second-order ToM stories were mediated by their deficits in general intellectual abilities, and there was an effect of remitted depression on the unaffected mothers' performance.

CONCLUSIONS

The results suggest that intact neurocognitive and general intellectual abilities are necessary in order patients and their unaffected parents to pass successfully ToM tasks. Patients and their unaffected parents show ToM deficits but these deficits are not similar. Patients show ToM deficits but these deficits seem to be a component of the pathophysiology of the illness (e.g., deficits in executive function, general intellectual abilities).

Schizophrenia-related RGS4 gene variations specifically disrupt prefrontal control of saccadic eye movements

BACKGROUND

The gene encoding the regulator of G-protein signaling subtype 4 (RGS4), located on chromosome 1q23-3, has been proposed as a possible susceptibility gene for schizophrenia and has been specifically linked to prefrontal cortical structural and functional integrity.

METHOD

The effects of four core single nucleotide polymorphisms (SNPs) within the RGS4 gene on oculomotor parameters in a battery of oculomotor tasks (saccade, antisaccade, smooth eye pursuit, fixation) were investigated in a sample of 2243 young male military conscripts.

RESULTS

The risk allele of RGS4SNP18 was found to be associated with two variables of antisaccade performance, increased error rate and variation in the correct antisaccade latency. By contrast, the same allele and also the risk allele of RGS4SNP4 led to an improvement in smooth eye pursuit performance (increased gain). Structural equation modeling confirmed that the combined gene variation of RGS4SNP4 and RGS4SNP18 was a significant predictor of antisaccade but not smooth eye pursuit performance.

CONCLUSIONS

These results provide evidence for a specific effect of schizophrenia-related RGS4 genotype variations to prefrontal dysfunction measured by oculomotor indices of performance in normal individuals, further validating the hypothesis that RGS4 is related to prefrontal dysfunction in schizophrenia.

Serotonin transporter gene variants and prediction of stress-induced risk for psychological distress

The response to psychosocial stress is influenced by both psychosocial factors and genetic vulnerability. The most investigated gene in gene × environment studies in abnormal response to environmental stressors is the one coding for the serotonin transporter (SLC6A4). Variability within this gene has been associated with functional brain differences, personality dimensions, reactivity to stress and risk for various psychopathological conditions. In the present study, we set out to investigate the association of common genetic variants within SLC6A4 with state psychopathology in a community sample homogeneously exposed to stress, thus inquiring about potential genetic differences in stress sensitivity. One thousand eight hundred seventy-five young conscripts were evaluated for psychopathological distress with the 90-item Symptoms Checklist Revised in their first 2 weeks of admission to obligatory military service. Of these, 1594 were genotyped for the biallelic ins/del polymorphism (5-HTTLPR S/L) within the promoter region of SLC6A4, as well as the variation within the 'long' 5-HTTLPR allele (rs25531A/G). Homozygous for the 5-HTTLPR S allele reported significantly higher scores for paranoid ideation as compared with L-allele carriers. Slight effects on other subscales were observed, but were not significant after correction for multiple testing. Despite limitations linked to the evaluation of psychopathology by a single general scale and multiple comparisons, the present study support a role of SLC6A4 in modulating abnormal responses to environmental stress. In particular, variation within this gene may confer risk for paranoid/defensive reactions under conditions of environmental stress associated with military induction.

Early adolescent cannabis exposure and positive and negative dimensions of psychosis

AIMS

To investigate the effect of exposure to cannabis early in adolescence on subclinical positive and negative symptoms of psychosis.

DESIGN

Cross-sectional survey in the context of an ongoing cohort study.

SETTING

Government-supported general population cohort study.

PARTICIPANTS

A total of 3500 representative 19-year olds in Greece.

MEASUREMENTS

Subjects filled in the 40-item Community Assessment of Psychic Experiences, measuring subclinical positive (paranoia, hallucinations, grandiosity, first-rank symptoms) and negative psychosis dimensions and depression. Drug use was also reported on.

FINDINGS

Use of cannabis was associated positively with both positive and negative dimensions of psychosis, independent of each other, and of depression. An association between cannabis and depression disappeared after adjustment for the negative psychosis dimensions. First use of cannabis below age 16 years was associated with a much stronger effect than first use after age 15 years, independent of life-time frequency of use. The association between cannabis and psychosis was not influenced by the distress associated with the experiences, indicating that self-medication may be an unlikely explanation for the entire association between cannabis and psychosis.

CONCLUSIONS

These results add credence to the hypothesis that cannabis contributes to the population level of expression of psychosis. In particular, exposure early in adolescence may increase the risk for the subclinical positive and negative dimensions of psychosis, but not for depression.

Is the excess risk of psychosis-like experiences in urban areas attributable to altered cognitive development?

BACKGROUND

Rates of psychotic disorder and related attenuated psychotic experiences are higher in urban areas. We examined to what degree differences between urban and rural areas could be attributed to differences in cognitive development.

METHOD

Scores on the nine subscales of the schizotypal personality questionnaire (SPQ) as well as IQ and specific neuropsychological functions of memory and attention were assessed in a representative sample of 943 young army conscripts from the 49 counties of Greece.

RESULTS

Young men from urban areas had higher scores on the SPQ subscale Odd beliefs/magical thinking (OR = 1.99, 95% CI: 1.42, 2.78), but lower scores on Excessive social anxiety (OR = 0.63, 95 % CI: 0.49, 0.81) and No close friends (OR = 0.42, 95% CI: 0.29, 0.62). Adjustment for demographic factors, IQ and specific neuropsychological functions did not change the results. When the lower scores on Excessive social anxiety and No close friends were taken into account, the differences on the Odd beliefs/magical thinking subscale became even more pronounced (OR = 2.33, 95% CI: 1.56, 3.49).

CONCLUSIONS

Young men from urban areas are socially more competent, but display higher levels of positive psychotic experiences, which are not mediated by lower IQ or higher levels of neuropsychological impairment.

Active eye fixation performance in 940 young men: effects of IQ, schizotypy, anxiety and depression

A total of 940 young men performed a task in which they actively maintained fixation for 50 s in three conditions: a). on a visual target, b). on a visual target while distracting targets appeared briefly on the periphery and c). with no visual target present. The same individuals completed psychometric evaluation tests measuring IQ, schizotypy and current state-dependent psychopathology. The proportion of fixation time decreased and saccade frequency increased in condition b compared wih condition a, and sequentially in condition c compared with condition b. A trend towards a decrease in proportion of fixation time and increase in saccade frequency was found as the subjects maintained fixation during the task and this time-dependent deterioration of performance was again most pronounced in condition c, less so in condition b and absent in condition a. Psychometric test scores were significantly correlated with fixation performance in the population. Worse performance in all three fixation conditions was observed for individuals with lower IQ scores. A deterioration of fixation performance with time in condition b was correlated with disorganization characteristics of schizotypy, suggesting that these individuals had difficulty maintaining active fixation in the presence of increased inhibitory load. A connection of such a difficulty with the frontal lobes and their role in the control of voluntary inhibitory functions is discussed.

Effects of direction on saccadic performance in relation to lateral preferences

A sample of 676 healthy young males performed visually guided saccades and antisaccades and completed the Porac-Coren questionnaire measuring lateral preferences. There was no difference in mean latency between rightward versus leftward saccades or for saccades executed in the left versus right hemispace. There was also no right/left asymmetry for individuals with left or right dominance as assessed by the lateral preferences questionnaire. The same results were observed for the latency of antisaccades and for the error rate in the antisaccade task. Finally, we did not confirm any substantial subpopulation of individuals with idiosyncratic left/right latency asymmetries that persisted both in the saccade and antisaccade task. These results suggest that neither latency nor antisaccade error rate are good indicators of lateral preferences in these tasks. Other oculomotor tasks might be more sensitive to hemifield differences, or cerebral hemispheric asymmetry is not present at the level of cortical organization of saccades and antisaccades.

Higher scores of self reported schizotypy in healthy young males carrying the COMT high activity allele

The gene for COMT is located on chromosome 22q11, an area that has been implicated in the pathogenesis of schizophrenia through linkage studies and through the detection of deletions in schizophrenics and velocardiofacial syndrome patients that often present psychotic symptomatology. Additionally catechol-O-methyl transferase activity has been found increased in schizophrenia and a functional polymorphism in the COMT gene itself has been associated with the disease, as well as with aggression in patients. We tested the hypothesis that COMT genotype for the functional Val158Met might contribute to the variance of self reported schizotypy and aggression scores in the normal population. We genotyped 379 healthy 18- to 24-year-old male individuals who had completed the PAS, SPQ and AQ questionnaires. Our results showed that self-reported schizotypy scores in both questionnaires were significantly related to COMT genotype (P = 0.028 for the PAS and P = 0.015 for the SPQ) with individuals homozygous for the high activity allele showing the highest scores. No significant differences were detected for AQ scores. We conclude that the COMT genotype for the functional Val158Met polymorphism is correlated to self-reported schizotypy in healthy males. This finding is in the same direction as reported findings on schizophrenia and it adds to the list of evidence that COMT or a nearby gene in linkage disequilibrium is involved in the pathogenesis of the disease.

The antisaccade task in a sample of 2,006 young men. I. Normal population characteristics

A population of 2,075 young men aged 18-25 years selected from the conscripts of the Greek Air Force performed an antisaccade task as part of a prospective study for the identification of risk factors in the development of psychoses. The aim of this study, which is ongoing, is to follow this population and investigate the possible predictive value of oculomotor, cognitive, and psychometric factors for the development of psychosis and other psychiatric conditions. In this report we present data concerning the antisaccade task in this population. We measured performance indices, including the percentage of errors (PE), the latencies of different eye movement responses (latency for correct antisaccades, errors, corrections), and performance in perseveration-prone trials. These indices were also evaluated with respect to IQ (measured by the Raven progressive matrices test) and educational level. Mean PE was 23%, with 17% variance. This large variance is of particular importance whenever the detection of a putative deviant behavior is explored. As mean latency of the first eye movement decreased, the PE increased, as did the latency variance. While the negative correlation between percentage of error and mean latency is well established, the relationship of the latency variability of the first response to error production has not been studied before. Thus, optimal performance appears to require both an intermediate mean latency and a small variability. Furthermore, performance seems to be affected by IQ (the higher the IQ score, the lower the percentage of errors). This report offers an analysis of the interindividual variation in the performance of the antisaccade task and discusses some of the sources of this variation.

The antisaccade task in a sample of 2,006 young males. II. Effects of task parameters

Antisaccade performance was investigated in a sample of 2,006 young males as part of a large epidemiological study investigating psychosis proneness. This report summarizes the effects of task parameters on performance using a sample of 55,678 antisaccade trials collected from a subpopulation of 947 individuals. Neither the amplitude nor the latency of an error prosaccade in the antisaccade task was correlated with the latency of the ensuing corrective antisaccade that almost always followed an error. However, the latency of the corrective antisaccade decreased with increasing stimulus distance. Concerning the effects of specific task parameters, trials with stimuli closer to the central fixation point and trials preceded by shorter fixation intervals resulted in more errors and longer latencies for the antisaccades. Finally, there were learning and fatigue effects reflected mainly in the error rate, which was greater at the beginning and at the end of the 5-min task. We used a model to predict whether an error or a correct antisaccade would follow a particular trial. All task parameters were significant predictors of the trial outcome but their power was negligible. However, when modeled alone, response latency of the first movement predicted 40% of errors. In particular, the smaller this latency was, the higher the probability of an error. These findings are discussed in light of current hypotheses on antisaccade production mechanisms involving mainly the superior colliculus.

Evidence that three dimensions of psychosis have a distribution in the general population

BACKGROUND

The aims of the study were: first to examine, using clinical symptoms of patients as a template, whether the correlated but independent dimensions of positive, negative and depressive symptoms that have been identified in clinical psychosis, also have a distribution as non-clinical experiences in the general population; and second, to establish to what degree population variation in experience of positive and negative features of psychosis is actually independent of experience of depression.

METHOD

In a representative population sample of 932 young men, we measured experiences of positive, negative and depressive features of psychosis, using a 40-item self-report instrument. Confirmatory factor analysis was used to compare the fit of hypothesized one-, two- and three-factor solutions.

RESULTS

A three-factor model of separate depressive, positive and negative dimensions provided a better fit to the data than either a two-factor or unidimensional model. All three dimensions were correlated with each other, but also showed good discriminant validity in relation to established scales, confirming their relative independence.

CONCLUSION

The data suggest that the correlated dimensions of clinical psychosis also have a distribution in the general population, and that depressive symptoms may form an integral part of psychosis-like experiences in the general population.

Elevation of D4 dopamine receptor mRNA in postmortem schizophrenic brain

The D4 dopamine (DA) receptor has been proposed to be a target for the development of a novel antipsychotic drug based on its pharmacological and distribution profile. There is much interest in whether D4 DA receptor levels are altered in schizophrenia, but the lack of an available receptor subtype-specific radioligand made this difficult to quantitate. In this study, we examined whether D4 mRNA levels are altered in different brain regions of schizophrenics compared to controls. Ribonuclease protection assays were carried out on total RNA samples isolated postmortem from frontal cortex and caudate brain regions of schizophrenics and matched controls. 32P-labelled RNA probes to the D4 DA receptor and to the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (G3PDH), were hybridised with the RNA samples, digested with ribonucleases to remove unhybridised probe, and separated on 6% sequencing gels. Densitometer analysis on the subsequent autoradiogams was used to calculate the relative optical density of D4 mRNA compared to G3PDH mRNA. Statistical analysis of the data revealed a 3-fold higher level (P<0.011) of D4 mRNA in the frontal cortex of schizophrenics compared to controls. No increase was seen in caudate. D4 receptors could play a role in mediating dopaminergic activity in frontal cortex, an activity which may be malfunctioning in schizophrenia.