A meta-analysis of the polyunsaturated fatty acid composition of erythrocyte membranes in schizophrenia

BACKGROUND

Membrane abnormalities in polyunsaturated fatty acids (PUFAs) have been reported in schizophrenia and have been associated with brain tissue loss in normal ageing. Therefore PUFA may be involved in the excessive brain tissue loss reported in schizophrenia.

METHODS

A systematic MEDLINE database search was conducted to identify studies that compared PUFAs in erythrocyte membranes in patients and controls. Patients were categorized by medication regime in medication naive first-episode patients, and patients receiving typical or atypical antipsychotics.

SAMPLE

Fourteen studies were included, comprising a total of 429 patients with schizophrenia and 444 healthy control subjects. Cohen's d effect sizes were calculated for PUFAs in erythrocyte membranes using the random-effects model. Combined Cohen's d was calculated separately for patients on different medication regime.

RESULTS

Medication-naive patients and patients taking typical antipsychotics showed significantly (p<0.01) decreased concentrations of arachidonic (AA), docosahexaenoic (DHA), and docosapentaenoic (DPA) acid. In addition, patients taking typical antipsychotics showed decreased linoleic (LA), dihomo-γ-linolenic acid (DGLA), eicosapentaenoic (EPA) and docosatetraenoic (DTA) acid (p<0.01). Patients taking atypical antipsychotics showed decreased DHA (p<0.01) only.

CONCLUSIONS

PUFA concentrations in erythrocyte membranes are decreased in schizophrenia. Of particular importance in patients are lower concentrations of DHA and AA, two fatty acids that are abundant in the brain and important precursors in the cell-signalling cascade.

Age at onset of non-affective psychosis in relation to cannabis use, other drug use and gender

BACKGROUND

Cannabis use is associated with an earlier age at onset of psychotic illness. The aim of the present study was to examine whether this association is confounded by gender or other substance use in a large cohort of patients with a non-affective psychotic disorder.

METHOD

In 785 patients with a non-affective psychotic disorder, regression analysis was used to investigate the independent effects of gender, cannabis use and other drug use on age at onset of first psychosis.

RESULTS

Age at onset was 1.8 years earlier in cannabis users compared to non-users, controlling for gender and other possible confounders. Use of other drugs did not have an additional effect on age at onset when cannabis use was taken into account. In 63.5% of cannabis-using patients, age at most intense cannabis use preceded the age at onset of first psychosis. In males, the mean age at onset was 1.3 years lower than in females, controlling for cannabis use and other confounders.

CONCLUSIONS

Cannabis use and gender are independently associated with an earlier onset of psychotic illness. Our findings also suggest that cannabis use may precipitate psychosis. More research is needed to clarify the neurobiological factors that make people vulnerable to this precipitating effect of cannabis.

Brain volume reductions in medication-naive patients with schizophrenia in relation to intelligence quotient

BACKGROUND

Global brain abnormalities such as brain volume loss and grey- and white-matter deficits are consistently reported in first-episode schizophrenia patients and may already be detectable in the very early stages of the illness. Whether these changes are dependent on medication use or related to intelligence quotient (IQ) is still debated.

METHOD

Magnetic resonance imaging scans were obtained for 20 medication-naive patients with first-episode schizophrenia and 26 matched healthy subjects. Volume measures of total brain grey and white matter, third and lateral ventricles and cortical thickness/surface were obtained. Differences between the groups were investigated, taking into account the effect of intelligence.

RESULTS

Medication-naive patients showed statistically significant reductions in whole-brain volume and cerebral grey- and white-matter volume together with lateral ventricle enlargement compared to healthy subjects. IQ was significantly lower in patients compared to controls and was positively associated with brain and white-matter volume in the whole group. No significant differences in cortical thickness were found between the groups but medication-naive patients had a significantly smaller surface in the left superior temporal pole, Heschl's gyrus and insula compared to controls.

CONCLUSIONS

Our findings suggest that brain volume loss is present at illness onset, and can be explained by the reduced surface of the temporal and insular cortex. These abnormalities are not related to medication, but IQ.

Unmet needs in patients with first-episode schizophrenia: a longitudinal perspective

BACKGROUND

This study aimed to identify the course of unmet needs by patients with a first episode of schizophrenia and to determine associated variables.

METHOD

We investigated baseline assessments in the European First Episode Schizophrenia Trial (EUFEST) and also follow-up interviews at 6 and 12 months. Latent class growth analysis was used to identify patient groups based on individual differences in the development of unmet needs. Multinomial logistic regression determined the predictors of group membership.

RESULTS

Four classes were identified. Three differed in their baseline levels of unmet needs whereas the fourth had a marked decrease in such needs. Main predictors of class membership were prognosis and depression at baseline, and the quality of life and psychosocial intervention at follow-up. Depression at follow-up did not vary among classes.

CONCLUSIONS

We identified subtypes of patients with different courses of unmet needs. Prognosis of clinical improvement was a better predictor for the decline in unmet needs than was psychopathology. Needs concerning social relationships were particularly persistent in patients who remained high in their unmet needs and who lacked additional psychosocial treatment.

Symptom dimensions are associated with progressive brain volume changes in schizophrenia

BACKGROUND

There is considerable variation in progressive brain volume changes in schizophrenia. Whether this is related to the clinical heterogeneity that characterizes the illness remains to be determined. This study examines the relationship between change in brain volume over time and individual variation in psychopathology, as measured by five continuous symptom dimensions (i.e. negative, positive, disorganization, mania and depression).

METHODS

Global brain volume measurements from 105 schizophrenia patients and 100 healthy comparison subjects, obtained at inclusion and 5-year follow-up, were used in this study. Symptom dimension scores were calculated by factor analysis of clinical symptoms. Using linear regression analyses and independent-samples t-tests, the relationship between symptom dimensions and progressive brain volume changes, corrected for age, gender and intracranial volume, was examined. Antipsychotic medication, outcome and IQ were investigated as potential confounders.

RESULTS

In patients, the disorganization dimension was associated with change in total brain (β=-0.295, p=0.003) and cerebellar (β=-0.349, p<0.001) volume. Furthermore, higher levels of disorganization were associated with lower IQ, irrespective of psychiatric status (i.e. patient or control). In healthy comparison subjects, disorganization score was not associated with progressive brain volume changes.

CONCLUSION

Heterogeneity in progressive brain volume changes in schizophrenia is particularly associated with variation in disorganization. Schizophrenia patients with high levels of disorganization exhibit more progressive decrease of global brain volumes and have lower total IQ. We propose that these patients form a phenotypically and biologically homogenous subgroup that may be useful for etiological (e.g., genetic) studies.

Interpreting treatment trials in schizophrenia patients: lessons learned from EUFEST

There are various procedures to account for missing values in clinical trials. Mixed Model and Last Observation Carried Forward (LOCF) analyses are commonly employed methods. We compared the two methods by reanalysing Positive and Negative Syndrome Scale (PANSS) scores from the European First Episode in Schizophrenia Trial (EUFEST). While the predefined Mixed Model analysis detected no differences between PANSS total score changes in first episode patients treated with haloperidol, amisulpride, quetiapine, olanzapine or ziprasidone over the course of a one year treatment trial, a LOCF analysis revealed significant differences in favor of the new generation antipsychotics over haloperidol. Implications for clinical trial design and the interpretation of such studies are discussed.

The genetic and environmental determinants of the association between brain abnormalities and schizophrenia: the schizophrenia twins and relatives consortium

BACKGROUND

Structural brain abnormalities are consistently found in schizophrenia (Sz) and have been associated with the familial risk for the disorder. We aim to define the relative contributions of genetic and nongenetic factors to the association between structural brain abnormalities and Sz in a uniquely powered cohort (Schizophrenia Twins and Relatives consortium).

METHODS

An international multicenter magnetic resonance imaging collaboration was set up to pool magnetic resonance imaging scans from twin pairs in Utrecht (The Netherlands), Helsinki (Finland), London (United Kingdom), and Jena (Germany). A sample of 684 subjects took part, consisting of monozygotic twins (n = 410, with 51 patients from concordant and 52 from discordant pairs) and dizygotic twins (n = 274, with 39 patients from discordant pairs). The additive genetic, common, and unique environmental contributions to the association between brain volumes and risk for Sz were estimated by structural equation modeling.

RESULTS

The heritabilities of most brain volumes were significant and ranged between 52% (temporal cortical gray matter) and 76% (cerebrum). Heritability of cerebral gray matter did not reach significance (34%). Significant phenotypic correlations were found between Sz and reduced volumes of the cerebrum (-.22 [-.30/-.14]) and white matter (-.17 [-.25/-.09]) and increased volume of the third ventricle (.18 [.08/.28]). These were predominantly due to overlapping genetic effects (77%, 94%, and 83%, respectively).

CONCLUSIONS

Some of the genes that transmit the risk for Sz also influence cerebral (white matter) volume.

The course of brain abnormalities in schizophrenia: can we slow the progression?

There is convincing evidence that schizophrenia is characterized by progressive brain volume changes during the course of the illness. In a large longitudinal study it was shown that different age-related trajectories of brain tissue loss are present in patients compared with healthy subjects, suggesting that brain maturation that occurs in the third and fourth decade of life is abnormal in schizophrenia. Studies show that medication intake is an important confounding factor when interpreting brain volume (change) abnormalities. Atypical antipsychotics have been found to be related to smaller decreases in tissue loss. Moreover, independent of antipsychotic medication intake, the brain volume abnormalities appear associated to the outcome of the illness. Before being able to intervene with therapies and prevent the brain from shrinking, one has to understand the underlying mechanism of the progressive changes in the brains of schizophrenia patients.

Premorbid school performance in twins concordant and discordant for bipolar disorder

BACKGROUND

Although the genetic risk to develop bipolar disorder is present from conception, the first frank symptoms of the illness generally become evident in late adolescence or early adulthood. However, except for pediatric bipolar disorder (PBD), it is still unclear when the first signs of the illness in adults become apparent and whether these are related to the genetic risk to develop bipolar disorder. This study examined whether underperformance at school precedes the onset of the illness and is a genetically related risk marker for developing bipolar disorder.

METHODS

Information on school performance was obtained using objective archival data from 53 bipolar twin pairs (24 monozygotic (MZ), 29 dizygotic (DZ)) and 42 healthy matched control twin pairs (23 MZ, 19 DZ).

RESULTS

Affected twin pairs completed significantly fewer years of education than did control twin pairs with no difference between bipolar patients and their non-bipolar cotwins. The underperformance at school in the affected twin pairs occurred in early adolescence at a significantly younger age than the control twin pairs and preceded the onset of the first frank episode of bipolar disorder by thirteen years. Median age at onset of underperformance was not different in the patients and their non-bipolar cotwins. The association between liability of bipolar disease and age of first underperformance was significant and could be explained by genetic factors.

LIMITATIONS

The sample is not a population based twin sample.

CONCLUSION

Underperformance at school during early adolescence may be a genetic marker for the vulnerability to develop bipolar disorder.

Predictive validity of a culturally informed diagnosis of schizophrenia: a 30 month follow-up study with first episode psychosis

Previous research has shown discrepancies between a standard diagnostic interview for schizophrenia (CASH) and a culture sensitive version of this instrument (CASH-CS) in Moroccan patients. More specifically we showed that among Moroccan immigrants the CASH-CS resulted in fewer patients with a diagnosis of schizophrenia compared with diagnoses based on the CASH, whereas for Native Dutch patients there was no difference between the CASH and the CASH-CS. The aim of the current study was to compare the predictive validity of a diagnosis of schizophrenia according to the CASH and CASH-CS.

METHOD

Thirty months after referral, 26 Moroccan and 26 native Dutch patients with a suspected first psychotic episode were compared with regard to 30-month diagnostic stability, symptom development, psychosocial functioning, medication use and hospitalization using baseline diagnoses based on the two versions of the CASH.

RESULTS

Moroccan patients who were diagnosed with schizophrenia using the standard CASH at baseline had a significantly better 30-month prognosis than native Dutch patients with the same CASH diagnosis. Prognosis of schizophrenia according to the CASH-CS was similar for Moroccans and native Dutch patients. Diagnostic stability according to the CASH was high for native Dutch (92%), but low for Moroccan patients (27%), whereas diagnostic stability according to the CASH-CS was high for both groups (85% and 81%, respectively).

CONCLUSION

These data raise questions regarding the validity of the standard CASH in Moroccan immigrants in The Netherlands and support the validity of the CASH-CS. As a consequence, there are serious doubts about the validity of previous studies showing an increased incidence of schizophrenia in immigrants using standard diagnostic procedures.

Genetic influences on thinning of the cerebral cortex during development

During development from childhood to adulthood the human brain undergoes considerable thinning of the cerebral cortex. Whether developmental cortical thinning is influenced by genes and if independent genetic factors influence different parts of the cortex is not known. Magnetic resonance brain imaging was done in twins at age 9 (N = 190) and again at age 12 (N = 125; 113 repeated measures) to assess genetic influences on changes in cortical thinning. We find considerable thinning of the cortex between over this three year interval (on average 0.05 mm; 1.5%), particularly in the frontal poles, and orbitofrontal, paracentral, and occipital cortices. Cortical thinning was highly heritable at age 9 and age 12, and the degree of genetic influence differed for the various areas of the brain. One genetic factor affected left inferior frontal (Broca's area), and left parietal (Wernicke's area) thinning; a second factor influenced left anterior paracentral (sensory-motor) thinning. Two factors influenced cortical thinning in the frontal poles: one of decreasing influence over time, and another independent genetic factor emerging at age 12 in left and right frontal poles. Thus, thinning of the cerebral cortex is heritable in children between the ages 9 and 12. Furthermore, different genetic factors are responsible for variation in cortical thickness at ages 9 and 12, with independent genetic factors acting on cortical thickness across time and between various brain areas during childhood brain development.

Movement disorders are associated with schizotypy in unaffected siblings of patients with non-affective psychosis

BACKGROUND

Movement disorders and schizotypy are both prevalent in unaffected siblings of patients with schizophrenia and both are associated with the risk of developing psychosis or schizophrenia. However, to date there has been no research into the association between these two vulnerability factors in persons with an increased genetic risk profile. We hypothesized that unaffected siblings of patients with non-affective psychosis have more movement disorders and schizotypy than healthy controls and that these co-occur.

METHOD

In a cross-sectional design we assessed the prevalence and inter-relationship of movement disorders and schizotypy in 115 unaffected siblings (mean age 27 years, 44% males) and 100 healthy controls (mean age 26 years, 51% males). Movement disorders were measured with the Abnormal Involuntary Movement Scale (AIMS), the Unified Parkinson Disease Rating Scale (UPDRS), the Barnes Akathisia Rating Scale (BARS), and one separate item for dystonia. Schizotypy was assessed with the Structured Interview for Schizotypy--Revised (SIS-R).

RESULTS

There were significant differences in the prevalence of movement disorders in unaffected siblings versus healthy controls (10% v. 1%, p<0.01) but not in the prevalence of schizotypy. Unaffected siblings with a movement disorder displayed significantly more positive and total schizotypy (p=0.02 and 0.03 respectively) than those without. In addition, dyskinesia correlated with positive schizotypy (r=0.51, p=0.02).

CONCLUSIONS

The association between movement disorders (dyskinesia in particular) with positive and total schizotypy in unaffected siblings suggests that certain vulnerability factors for psychosis or schizophrenia cluster in a subgroup of subjects with an increased genetic risk of developing the disease.

Familial sinistrality and handedness in patients with first episode schizophrenia: the EUFEST study

The population with schizophrenia is characterised by a leftward shift in handedness-sinistrality. However, findings are inconsistent in chronic patients, and familial sinistrality (FS), defined as the presence of left-handed close relatives, might contribute to the discrepancies. Therefore the aim of this study was to investigate the strength of manual lateralisation in patients with first episode schizophrenia, taking into account familial sinistrality. The Edinburgh Inventory (EI) allowed us to categorise 179 patients from the EUFEST study and 189 controls presenting "strong handedness" (SH: EI absolute value between ∣81∣ and ∣100∣) or "weak-handedness" (WH: EI value between -80 and +80). The nominal logistic regression did not show an FS effect, but a nearly significant interaction between illness and FS (p =.07). There were fewer participants without FS presenting SH among patients (99/151: 65.6%) than among controls (134/164: 81.7%, p =.001). In contrast, the number of participants with FS presenting SH was similar between controls (68%) and patients (75%, p =.57). The presence of left-handed relatives (FS + ) tended to reduce manual lateralisation, but only in controls. This supports the notion that reduced manual lateralisation in schizophrenia is related to the illness rather than to familial left-handedness.

Microstructural alterations of the arcuate fasciculus in schizophrenia patients with frequent auditory verbal hallucinations

Auditory verbal hallucinations (AVH) is a common and stressful symptom of schizophrenia. Disrupted connectivity between frontal and temporo-parietal language areas, giving rise to the misattribution of inner speech, is speculated to underlie this phenomenon. Disrupted connectivity should be reflected in the microstructure of the arcuate fasciculi (AF); the main connection between frontal and temporo-parietal language areas. In this study we compared microstructural properties of the AF and three other fiber tracts (cortical spinal tract, cingulum and uncinate fasciculus), between 44 schizophrenia patients with chronic severe hallucinations and 42 control subjects using diffusion tensor imaging (DTI) and magnetic transfer imaging (MTI). The DTI scans were used to compute fractional anisotropy (FA) and to reconstruct the fiber bundles of interest, while the MTI scans were used to compute magnetic transfer ratio (MTR) values. The patient group showed a general decrease in FA for all bundles. In the arcuate fasciculus this decreased FA was coupled to a significant increase in MTR values. A correlation was found between mean MTR values in both arcuate fasciculi and the severity of positive symptoms. The combination of decreased FA and increased MTR values observed in the arcuate fasciculi in patients suggests increased free water concentrations, probably caused by degraded integrity of the axons or the supportive glia cells. This suggests that disintegrated fiber integrity in the connection between frontal and temporo-parietal language areas in the schizophrenia patients is associated with their liability for auditory verbal hallucinations.

Cannabis use at a young age is associated with psychotic experiences

BACKGROUND

Cannabis use is associated with psychosis and a range of subclinical psychiatric symptoms. The strength of this association depends on dosage and age at first use. The current study investigates whether level of cannabis exposure and starting age are associated with specific profiles of subclinical symptoms.

METHOD

We collected cross-sectional data from a young adult population sample by administering an online version of the Community Assessment of Psychic Experiences (CAPE). Cannabis exposure was quantified as the amount of Euros spent on cannabis per week and the age of initial cannabis use. The primary outcome measure was the odds ratio (OR) to belong to the highest 10% of scores on the total CAPE and the positive-, negative- and depressive symptom dimensions.

RESULTS

In 17 698 adolescents (mean age 21.6, s.d.=4.2 years), cannabis use at age 12 years or younger was strongly associated with a top 10% score on psychotic experiences [OR 3.1, 95% confidence interval (CI) 2.1-4.3] and to a lesser degree with negative symptoms (OR 1.7, 95% CI 1.1-2.5). The OR of heavy users (>€25/week) for negative symptoms was 3.4 (95% CI 2.9-4.1), for psychotic experiences 3.0 (95% CI 2.4-3.6), and for depressive symptoms 2.8 (95% CI 2.3-3.3).

CONCLUSIONS

Early start of cannabis use is strongly associated with subclinical psychotic symptoms and to a lesser degree with negative symptoms, while smoking high amounts of cannabis is associated with increased levels of all three symptom dimensions: psychotic, negative and depressive. These results support the hypothesis that the impact of cannabis use is age specific.

Association between cannabis and psychiatric hospitalization

OBJECTIVE

To investigate the relationship between cannabis use and mental health.

METHOD

A cross-sectional analysis in a sample of 17 698 individuals with a mean age of 22 years (SD: 4.2). Participants provided information on the amount and initial age of cannabis use and history of psychiatric hospitalizations through a web-based questionnaire. To quantify Δ(9) -tetrahydrocannabinol exposure, we operationalized cannabis use as the amount of money spent on cannabis per week over the last month. The odds ratio of having a history of psychiatric hospitalizations was the primary outcome measure.

RESULTS

We found a dose-response relationship between the amount of cannabis use and the odds for psychiatric hospitalization. Adjusted odds ratios for hospitalization increased with the amount of cannabis consumed from 1.6 (95% CI: 1.1-2.3) in incidental users to 6.2 (95% CI: 4.3-8.9) in heavy users (>€25/week). Our data suggested that concomitant drug use was an intermediate factor. Exposure to cannabis before the age of 12 years was found to carry a 4.8 (95% CI: 2.9-7.8) times increased odds for past psychiatric hospitalizations.

CONCLUSION

We conclude that early and heavy uses of cannabis are each and independently associated with poor mental health in its users.

Ziprasidone vs olanzapine in recent-onset schizophrenia and schizoaffective disorder: results of an 8-week double-blind randomized controlled trial

INTRODUCTION

Head-to-head comparisons of antipsychotics have predominantly included patients with chronic conditions. The aim of the present study was to compare the efficacy and tolerability of ziprasidone and olanzapine in patients with recent-onset schizophrenia.

METHODS

The study was an 8-week, double-blind, parallel-group, randomized, controlled multicenter trial (NCT00145444). Seventy-six patients with schizophreniform disorder, schizophrenia or schizoaffective disorder (diagnosis < 5 y), and a maximum lifetime antipsychotic treatment < 16 weeks participated in the study. Efficacy of ziprasidone (80-160 mg/d) and olanzapine 10-20 mg was measured using the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impression (CGI) Scale, the Calgary Depression Scale for Schizophrenia (CDSS), and the Heinrich Quality of Life Scale (HQLS); tolerability assessments included laboratory assessments, body weight, and electroencephalogram.

RESULTS

Olanzapine (n = 34) and ziprasidone (n = 39) showed equal efficacy as measured by the PANSS, CDSS, CGI, and HQLS. However, mean weight gain was significantly higher in the olanzapine group (6.8 vs 0.1 kg, P < .001). Ziprasidone was associated with decreasing levels of triglycerides, cholesterol, and transaminases, while these parameters increased in the olanzapine group (all P values < .05). There were no significant differences in fasting glucose and prolactin levels or in cardiac or sexual side effects. Patients on ziprasidone used biperiden for extrapyramidal side effects more frequently (P < .05).

DISCUSSION

The results of this study indicate that ziprasidone and olanzapine have comparable therapeutic efficacy but differ in their side effect profile. However, there is a risk of a type II error with this sample size. Clinically significant weight gain and laboratory abnormalities appear early after initiating treatment and are more prominent with olanzapine, while more patients on ziprasidone received anticholinergic drugs to treat extrapyramidal symptoms.

Effects on cognitive functioning after olanzapine-ziprasidone crossover in recent-onset schizophrenia

INTRODUCTION

To enhance functional outcome in schizophrenia improvement of cognitive symptoms is crucial.

EXPERIMENTAL PROCEDURES

Using a comprehensive test battery, this follow-up examines cognitive effects in patients with recent-onset schizophrenia after a change of medication following insufficient clinical response and intolerance.

RESULTS

After eight weeks cognitive outcomes had not improved in the patients having switched from olanzapine to ziprasidone (n=11; mean dose 136 mg) nor in those having switched from ziprasidone to olanzapine (n=10; mean 16 mg), while the symptoms of patients maintaining olanzapine (n=18; mean 10.9 mg) or ziprasidone (n=18; mean 88.9 mg) treatment had not improved further.

DISCUSSION

The findings suggest that also in early-stage schizophrenia the antipsychotics tested affect cognitive symptoms similarly.

Cigarette smoking and progressive brain volume loss in schizophrenia

It is unknown whether the reported brain loss in schizophrenia can be attributed to the effects of tobacco smoking. 96 Patients (54 smokers/42 non-smokers) and 113 control subjects (35/78) were included in a 5-year longitudinal MRI study. Despite the higher prevalence of smoking behavior and the higher number of cigarettes consumed per day in the patients, cigarette smoking did not explain the excessive cerebral (gray matter) volume decreases in the patients. Moreover, smoking was not associated with brain volume change over time in the healthy subjects. However, extremely heavy smoking may contribute to excessive gray matter volume loss in schizophrenia.

The involvement of GSK3beta in bipolar disorder: integrating evidence from multiple types of genetic studies

We aimed to get a comprehensive insight into the genetic evidence supporting the role of GSK3beta in bipolar disorder (BD). Using broad searches in NCBI's PubMed and the Genetic Association Database we looked for association, whole-genome linkage, genome-wide association, gene expression, pharmocogenomic, epigenetic, cytogenetic, and mouse model studies performed for BD until July 2009. Per gene, we rated the degree of converging evidence across these types of genetic studies. The genes most consistently associated with BD in the genetic studies we reviewed were GSK3beta , GRK3, 5-HTTLPR, GRIN3, COMT, and GLUR3. GSK3beta stood out as it was implicated in at least five types of genetic studies. Although our results are limited by design differences of included studies and possibly by publication bias, GSK3beta is a plausible candidate gene for BD from a pharmacological and a genetic perspective. Future studies investigating the effects of GSK3beta manipulation in BD seem warranted.

First contact incidence of psychotic disorders among native Dutch and Moroccan immigrants in the Netherlands: influence of diagnostic bias

BACKGROUND

Several studies have reported increased incidence rates of psychotic disorders among immigrant groups. Surprisingly, the cross-cultural validity of the diagnostic instruments that were used was never tested.

AIMS

To examine whether the incidence rates of psychotic disorders including schizophrenia among Moroccan immigrants to the Netherlands remain increased when a cultural sensitive diagnostic interview is used.

METHOD

We compared first contact incidence with a standard and a cultural sensitive version of a diagnostic interview.

RESULTS

Age and gender adjusted relative risk for psychotic disorders and schizophrenia among Moroccans compared to native Dutch was 7.9 (95% CI 4.7-13.5) and 7.8 (95% CI 4.0-15.2) respectively based on the standard diagnostic interview and 4.2 (95% CI 2.3-7.9) and 1.5 (0.5-4.3) respectively based on the cultural sensitive version the diagnostic interview.

CONCLUSION

First contact incidence of schizophrenia among Moroccans was no longer significantly higher than among ethnic Dutch people when a cultural sensitive diagnostic procedure was applied.

Human fronto-tectal and fronto-striatal-tectal pathways activate differently during anti-saccades

Almost all cortical areas in the vertebrate brain take part in recurrent connections through the subcortical basal ganglia (BG) nuclei, through parallel inhibitory and excitatory loops. It has been suggested that these circuits can modulate our reactions to external events such that appropriate reactions are chosen from many available options, thereby imposing volitional control over behavior. The saccade system is an excellent model system to study cortico-BG interactions. In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG. In an event-related functional magnetic resonance imaging (fMRI) paradigm participants made pro- and anti-saccades. A diffusion tensor imaging (DTI) scan was made for reconstruction of white matter tracts between the FEF, CN and SC. DTI fiber tracts were used to divide both the left and right FEF into two sub-areas, projecting to either ipsilateral SC or CN. For each of these FEF zones an event-related fMRI timecourse was extracted. In general activity in the FEF was larger for anti-saccades. This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN. These findings suggest that activity along the contralateral FEF-SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade.

Gray's BIS/BAS dimensions in non-comorbid, non-medicated social anxiety disorder

Gray's behavioural inhibition and behavioural activation (BIS/BAS) neural systems model has led to research on approach and withdrawal as the two most fundamental dimensions of affective behaviour, and their role in psychopathology. Although Gray proposed the BIS as the neurological basis of anxiety, there are no reports examining approach and withdrawal predispositions in social anxiety disorder. Here we report approach and withdrawal predispositions in a group of 23 non-medicated individuals with social anxiety disorder (SAD) without co-morbid depression and in 48 normal controls. Results show increased BIS and decreased BAS fun-seeking in SAD subjects thereby underscoring Gray's dimensional model.

"Forward genetics" as a method to maximize power and cost-efficiency in studies of human complex traits

There is increasing interest in methods to disentangle the relationship between genotype and (endo)phenotypes in human complex traits. We present a population-based method of increasing the power and cost-efficiency of studies by selecting random individuals with a particular genotype and then assessing the accompanying quantitative phenotypes. Using statistical derivations, power- and cost graphs we show that such a “forward genetics” approach can lead to a marked reduction in sample size and costs. This approach is particularly apt for implementing in epidemiological studies for which DNA is already available but the phenotyping costs are high.