Psychosis and brain volume changes during the first five years of schizophrenia

The underlying mechanisms explaining brain volume changes in schizophrenia are not yet understood, but psychosis might be related to these changes. Forty-eight patients with first-episode schizophrenia underwent Magnetic Resonance Imaging brain scanning at inclusion and after five years. An association was found between longer duration of psychosis, larger gray matter volume decrease and larger ventricular volume increase. These findings strongly suggest that psychosis contributes to brain volume reductions found in schizophrenia.

An association screen of myelin-related genes implicates the chromosome 22q11 PIK4CA gene in schizophrenia

Several lines of evidence, including expression analyses, brain imaging and genetic studies suggest that the integrity of myelin is disturbed in schizophrenia patients. In this study, we first reconstructed a pathway of 138 myelin-related genes, all involved in myelin structure, composition, development or maintenance. Then we performed a two-stage association analysis on these 138 genes using 771 single nucleotide polymorphisms (SNPs). Analysis of our data from 310 cases vs 880 controls demonstrated association of 10 SNPs from six genes. Specifically, we observed highly significant P-values for association in PIK4CA (observed P=6.1 x 10(-6)). These findings remained significant after Bonferroni correction for 771 tests. The PIK4CA gene is located in the chromosome 22q11 deletion syndrome region, which is of particular interest because it has been implicated in schizophrenia. We also report weak association of SNPs in PIK3C2G, FGF1, FGFR1, ARHGEF10 and PSAP (observed P<or=0.01). Our approach--of screening genes involved in a particular pathway for association--resulted in identification of several, mostly novel, genes associated with the risk of developing schizophrenia in the Dutch population.

The genetics of symptom dimensions of schizophrenia: review and meta-analysis

BACKGROUND

The use of symptom dimensions of schizophrenia as quantitative phenotypes has been proposed as a mean to reduce the heterogeneity of schizophrenia and facilitate genetic research. However, the genetic background of symptom dimensions is not clear.

AIM

We aim to investigate whether the symptom dimensions "reality distortion", "psychomotor poverty" and "disorganization" are heritable phenotypes.

METHOD

We performed a Medline search including all papers from 1980 to August 2007. In addition to reviewing the articles, we performed meta-analyses on these studies where possible.

RESULTS

We identified 18 relevant papers. Only the studies on affected sibling pairs were suitable for meta-analysis. Data from twin and affected sibling studies are consistent with a genetic contribution to the disorganization dimension. However these studies did not unequivocally support a large genetic contribution to neither the reality distortion symptom dimension nor to the psychomotor poverty symptom dimension. In contrast several molecular genetic studies did report associations of genes with psychomotor poverty.

CONCLUSIONS

These data suggest that only the disorganization symptom dimension may provide an useful alternative phenotype for genetic research. More research is required to make any definitive conclusions.

Maternal depression, child behavior, and injury

BACKGROUND

Few data exist on the effect of maternal depression on child injury outcomes and mediators of this relationship.

OBJECTIVE

To examine the relationship between mothers' depressive symptoms and medically attended injuries in their children and the potential mediating role of child behavior.

DESIGN/METHODS

A cohort of mother-child dyads from the National Longitudinal Study of Youth followed from 1992 to 1994. The primary exposure variable was maternal depressive symptoms as measured by the Center for Epidemiologic Studies Depression Scale in 1992. Child behavior was assessed by the Behavior Problems Index externalizing subscale. Logistic regression was used to examine the relationship between depressive symptoms, child behavior, and injury reported in the prior year in 1994.

RESULTS

94 medically attended injuries were reported in the 1106 children (8.5%); two-thirds were sustained in the home environment. Maternal depressive symptoms significantly increased the risk of child injury; injury risk increased 4% for every 1-point increase in depressive symptoms (adjusted OR 1.04, 95% CI 1.01 to 1.08, p=0.02). Increasing maternal depressive symptoms also increased the risk of externalizing behavior problems (adjusted OR 1.06, 95% CI 1.03 to 1.09), but externalizing behavior problems did not significantly mediate the relationship between maternal symptoms and child injury.

CONCLUSIONS

Increasing depressive symptoms in mothers was associated with an increased risk of child injury. Child behavior did not significantly mediate the association between maternal depressive symptoms and child injury in this cohort. Greater recognition, referral, and treatment of depressive symptoms in mothers may have effects on child behavior and injury risk.

The processing of emotional prosody and semantics in schizophrenia: relationship to gender and IQ

BACKGROUND

Female patients with schizophrenia are less impaired in social life than male patients. Because social impairment in schizophrenia has been found to be associated with deficits in emotion recognition, we examined whether the female advantage in processing emotional prosody and semantics is preserved in schizophrenia.

METHOD

Forty-eight patients (25 males, 23 females) and 46 controls (23 males, 23 females) were assessed using an emotional language task (in which healthy women generally outperform healthy men), consisting of 96 sentences in four conditions: (1) neutral-content/emotional-tone (happy, sad, angry or anxious); (2) neutral-tone/emotional-content; (3) emotional-tone/incongruous emotional-content; and (4) emotional-content/incongruous emotional-tone. Participants had to ignore the emotional-content in the third condition and the emotional-tone in the fourth condition. In addition, participants were assessed with a visuospatial task (in which healthy men typically excel). Correlation coefficients were computed for associations between emotional language data, visuospatial data, IQ measures and patient variables.

RESULTS

Overall, on the emotional language task, patients made more errors than control subjects, and women outperformed men across diagnostic groups. Controlling for IQ revealed a significant effect on task performance in all groups, especially in the incongruent tasks. On the rotation task, healthy men outperformed healthy women, but male patients, female patients and female controls obtained similar scores.

CONCLUSION

The advantage in emotional prosodic and semantic processing in healthy women is preserved in schizophrenia, whereas the male advantage in visuospatial processing is lost. These findings may explain, in part, why social functioning is less compromised in women with schizophrenia than in men.

Social judgement in clinically stable patients with schizophrenia and healthy relatives: behavioural evidence of social brain dysfunction

BACKGROUND

Patients with schizophrenia have been found to display abnormalities in social cognition. The aim of the study was to test whether patients with schizophrenia and unaffected first-degree relatives of schizophrenic patients display behavioural signs of social brain dysfunction when making social judgements.

METHOD

Eighteen patients with schizophrenia, 24 first-degree unaffected relatives and 28 healthy comparison subjects completed a task which involves trustworthiness judgements of faces. A second task was completed to measure the general ability to recognize faces.

RESULTS

Patients with schizophrenia rated faces as more trustworthy, especially those that were judged to be untrustworthy by healthy comparison subjects. Siblings of schizophrenia patients display the same bias, albeit to a lesser degree.

CONCLUSIONS

The pattern of more positive trustworthiness judgements parallels the results from studies of patients with abnormalities in brain areas involved in social cognition. Because patients and siblings did not differ significantly from controls in their general ability to recognize faces, these findings cannot be dismissed as abnormalities in face perception by itself.

Is MYO9B the missing link between schizophrenia and celiac disease?

There has long been discussion on the correlation between schizophrenia and autoimmune diseases (especially celiac disease), which makes the recently discovered celiac disease risk factor, MYO9B, an attractive functional and positional candidate gene for schizophrenia. To test this hypothesis we compared allele frequencies of three MYO9B tag SNPs in 315 schizophrenia cases and 1,624 healthy controls in a genetic association study. Highly significant differences in allele frequencies between schizophrenia cases and healthy controls were observed for SNP rs2305767 in intron 14 of MYO9B (P = 1.16 x 10(-4); OR 1.41, 95% CI 1.18-1.67). We demonstrate significant association of allelic variants in MYO9B with schizophrenia. To our knowledge, this is the first molecular genetic evidence for a correlation between autoimmune diseases and the risk of developing schizophrenia.

The need for culture sensitive diagnostic procedures: a study among psychotic patients in Morocco

OBJECTIVE

We examine the procedural validity of a standardized instrument for the diagnosis of psychotic disorders in Morocco.

METHOD

Twenty-nine patients from Casablanca, Morocco, with a psychotic or mood disorder were examined using the Comprehensive Assessment of Symptoms and History (CASH) an adapted version using cultural formulation to make the instrument more culturally sensitive (CASH-CS). Chance corrected agreement was calculated between diagnoses based on these two versions of CASH and independent clinical diagnoses according to local psychiatrists.

RESULTS

Agreement for traditional CASH versus clinical diagnosis and for CASH versus CASH-CS was low (kappa = -0.19; SD 0.16 and kappa = 0.21; SD 0.16, respectively). De CASH-CS, showed good agreement with clinical diagnosis (kappa = 0.79; SD 0.11).

CONCLUSION

Standardized instruments for the assessment of psychosis such as the CASH may be liable to cultural misinterpretations. This may be relevant to the interpretation of the high incidence rates of schizophrenia among immigrants.

SIGNIFICANT OUTCOMES

Agreement between a culturally naïve version of a standardized diagnostic instrument for the assessment of psychosis and clinical diagnosis by Moroccan psychiatrists is poor. Adding additional probes and decision rules based on cultural formulation improves agreement with clinical diagnosis significantly.

LIMITATIONS

The study was conducted in a small sample. Both versions of CASH were administered by the same interviewer in a single interview session.

CNTNAP2 gene dosage variation is associated with schizophrenia and epilepsy

A homozygous mutation of the CNTNAP2 gene has been associated with a syndrome of focal epilepsy, mental retardation, language regression and other neuropsychiatric problems in children of the Old Order Amish community. Here we report genomic rearrangements resulting in haploinsufficiency of the CNTNAP2 gene in association with epilepsy and schizophrenia. Genomic deletions of varying sizes affecting the CNTNAP2 gene were identified in three non-related Caucasian patients. In contrast, we did not observe any dosage variation for this gene in 512 healthy controls. Moreover, this genomic region has not been identified as showing large-scale copy number variation. Our data thus confirm an association of CNTNAP2 to epilepsy outside the Old Order Amish population and suggest that dosage alteration of this gene may lead to a complex phenotype of schizophrenia, epilepsy and cognitive impairment.

Effects of cross-sex hormones on cerebral activation during language and mental rotation: An fMRI study in transsexuals

Androgens and estrogens affect the performance on certain cognitive tests, particularly those measuring verbal fluency and mental rotation. Their effects on cognition have frequently been attributed to changes in cerebral lateralization. This study tested the impact of a reversal of the sex steroid milieu on cerebral activation and lateralization during verbal and spatial tasks in transsexuals. fMRI scans were obtained from 6 female-to-male and 8 male-to-female transsexuals at baseline and after cross-sex steroid treatment. Activation was measured during language and mental rotation tasks. Language activation increased after sex steroid treatment in both groups (F(1,12) =3.7, p=0.08), and total language activity was correlated to post-treatment estradiol levels (rho=0.54, p=0.05). Lateralization was not affected by the reversal of sex steroid milieus (F(1,12)=1.47, p=0.25). Activation during mental rotation did not increase during treatment (F(1,12)=0.54, p=0.34), but post-treatment testosterone levels correlated to total activation during mental rotation (rho=0.64, p=0.01). Findings suggest that sex steroids may influence cerebral activation, but lateralization remains stable.

Assessment of cognitive brain function in ecstasy users and contributions of other drugs of abuse: results from an FMRI study

Heavy ecstasy use has been associated with neurocognitive deficits in various behavioral and brain imaging studies. However, this association is not conclusive owing to the unavoidable confounding factor of polysubstance use. The present study, as part of the Netherlands XTC Toxicity study, investigated specific effects of ecstasy on working memory, attention, and associative memory, using functional magnetic resonance imaging (fMRI). A large sample (n=71) was carefully composed based on variation in the amount and type of drugs that were used. The sample included 33 heavy ecstasy users (mean 322 pills lifetime). Neurocognitive brain function in three domains: working memory, attention, and associative memory, was assessed with performance measures and fMRI. Independent effects of the use of ecstasy, amphetamine, cocaine, cannabis, alcohol, tobacco, and of gender and IQ were assessed and separated by means of multiple regression analyses. Use of ecstasy had no effect on working memory and attention, but drug use was associated with reduced associative memory performance. Multiple regression analysis showed that associative memory performance was affected by amphetamine much more than by ecstasy. Both drugs affected associative memory-related brain activity, but the effects were consistently in opposite directions, suggesting that different mechanisms are at play. This could be related to the different neurotransmitter systems these drugs predominantly act upon, that is, serotonin (ecstasy) vs dopamine (amphetamine) systems.

Investigating gene environment interaction in complex diseases: increasing power by selective sampling for environmental exposure

BACKGROUND

The often limited influence of disease associated alleles on the vulnerability to complex diseases has lead to increased interest in environmental interaction with genotype. However, gene environmental interactions (GEIs) are not easily studied, since high numbers of subjects are required to detect GEI.

METHODS AND RESULTS

This study provides a potential useful method to increase the power of such studies through selective sampling for environmental exposure. We show that selecting the top and bottom 10% regarding environmental exposure can lead to a 70% reduction in the required number of subjects for genotyping.

CONCLUSION

This study demonstrates the potential usefulness of selective sampling in the study of the interplay between genes and environment. The reduction of required subjects can be particularly advantageous in studies where genotyping is extensive, such as in whole genome screens or in studies where phenotyping is expensive.

Reviewing the role of the genes G72 and DAAO in glutamate neurotransmission in schizophrenia

We review the role of two susceptibility genes; G72 and DAAO in glutamate neurotransmission and the aetiology of schizophrenia. The gene product of G72 is an activator of DAAO (D-amino acid oxidase), which is the only enzyme oxidising D-serine. D-serine is an important co-agonist for the NMDA glutamate receptor and plays a role in neuronal migration and cell death. Studies of D-serine revealed lower serum levels in schizophrenia patients as compared to healthy controls. Furthermore, administration of D-serine as add-on medication reduced the symptoms of schizophrenia. The underlying mechanism of the involvement of G72 and DAAO in schizophrenia is probably based on decreased levels of D-serine and decreased NMDA receptor functioning in patients. The involvement of this gene is therefore indirect support for the glutamate dysfunction hypothesis in schizophrenia.

Incidental use of ecstasy: no evidence for harmful effects on cognitive brain function in a prospective fMRI study

RATIONALE

Heavy ecstasy use in humans has been associated with cognitive impairments and changes in cognitive brain function supposedly due to damage to the serotonin system. There is concern that even a single dose of 3,4-methylenedioxymethamphetamine may be neurotoxic, but very little is known about the consequences of a low dose of ecstasy for cognitive brain function.

OBJECTIVES

The objective of the study was to assess the effects of a low dose of ecstasy on human cognitive brain function using functional magnetic resonance imaging (fMRI).

MATERIALS AND METHOD

We prospectively studied, as part of the NeXT (Netherlands XTC toxicity) study, sustained effects of a low dose of ecstasy on brain function in 25 subjects before and after their first episode of ecstasy use (mean 2.0 +/- 1.4 ecstasy pills, on average 11.1 +/- 12.9 weeks since last ecstasy use), compared to 24 persistent ecstasy-naive controls, also measured twice and matched with the novice users on age, gender, IQ, and cannabis use. Cognitive brain function was measured in the domains of working memory, selective attention, and associative memory using fMRI.

RESULTS

No significant effects were found of a low dose of ecstasy on working memory, selective attention, or associative memory neither at the behavioral level nor at the neurophysiological level.

CONCLUSIONS

This study yielded no firm evidence for sustained effects of a low dose of ecstasy on human cognitive brain function. The present findings are relevant for the development of prevention and harm reduction strategies. Furthermore, the study is relevant to the discussion concerning potential therapeutic use of ecstasy.

Hippocampal volume and subcortical white matter lesions in late life depression: comparison of early and late onset depression

BACKGROUND

Reduced hippocampal volume and increased prevalence of subcortical white matter lesions are associated with both recurrent early onset depression (EOD) and late onset depression (LOD). It is not clear whether these two factors differentially affect the age of onset of first depression. Therefore, we wished to investigate the relationship between age of first depression onset and hippocampal volume, with adjustment for subcortical white matter lesions.

METHODS

MRI brain scans were used to compare hippocampal volumes and white matter lesions between age matched female patients (>60 years) with recurrent EOD and LOD and healthy controls.

RESULTS

When comparing the three groups and adjusting for age, the Mini-Mental State Examination score, total brain volume and total hippocampal volume were significantly smaller in patients with EOD compared with controls (5.6 vs 6.1 ml; p = 0.04). The prevalence of larger subcortical white matter lesions was higher in patients with LOD compared with patients with EOD (47% vs 8%; p = 0.002). Patients with LOD did not differ in hippocampal volume from patients with EOD or from controls.

CONCLUSIONS

In late life depression, age of first depression onset may distinguish between different independent neuropathological mechanisms. A small hippocampus volume may be a neuroanatomical marker of EOD depression and larger subcortical white matter lesions could be an intermediate between cerebrovascular disease and LOD.

Cerebral volume measurements and subcortical white matter lesions and short-term treatment response in late life depression

BACKGROUND

Late life depression is associated with volumetric reductions of gray matter and increased prevalence of subcortical white matter lesions. Previous studies have shown a poorer treatment outcome in those with more severe structural brain abnormalities. In this study, quantitative and semi-quantitative magnetic resonance imaging (MRI) measures were studied in relation to response to a 12-week controlled antidepressant monotherapy trial.

METHODS

MRI (1.5 T) brain scans of 42 elderly inpatients with major depression, of which 23 were non-responder to a controlled 12-week antidepressant monotherapy trial, were acquired. In addition, clinical outcome was assessed after a one year period. Measures were volumes of global cerebral and subcortical structures.

RESULTS

After controlling for confounding, no differences were found between non-responders and responders after 12 weeks and after one year in volumes of cerebral gray and white matter, orbitofrontal cortex, hippocampus and white matter lesions.

CONCLUSIONS

Structural brain measures associated with late life depression may not be related to short-term treatment response.

Test-retest reliability of fMRI activation during prosaccades and antisaccades

Various studies have investigated reproducibility of fMRI results. Whereas group results can be highly reproducible, individual activity maps tend to vary across sessions. Individual reliability is of importance for the application of fMRI in endophenotype research, where brain activity is linked to genetic polymorphisms. In this study, the test-retest reliability of activation maps during the antisaccade paradigm was assessed for individual and group results. Functional MRI images were acquired during two sessions of prosaccades and antisaccades in twelve healthy subjects using an event-related fMRI design. Reliability was assessed for both individual and group-wise results. In addition, the reliability of differences between subjects was established in predefined regions of interest. The reliability of group activation maps was high for prosaccades and antisaccades, but only moderate for antisaccades vs. prosaccades, probably as a result of low statistical power of individual results. Reproducibility of individual subject maps was highly variable, indicating that reliable results can be obtained in some but not all subjects. Reliability of individual activity maps was largely explained by individual differences in the global temporal signal to noise ratio (SNR). As the global SNR was stable over sessions, it explained a large portion of the differences between subjects in regional brain activation. A low SNR in some subjects may be dealt with either by improving the statistical sensitivity of the fMRI procedure or by subject exclusion. Differences in the global SNR between subjects should be addressed before using regional brain activation as phenotype in genetic studies.

Effects of frequent cannabis use on hippocampal activity during an associative memory task

Interest is growing in the neurotoxic potential of cannabis on human brain function. We studied non-acute effects of frequent cannabis use on hippocampus-dependent associative memory, investigated with functional Magnetic Resonance Imaging (fMRI) in 20 frequent cannabis users and 20 non-users matched for age, gender and IQ. Structural changes in the (para)hippocampal region were measured using voxel-based morphometry (VBM). Cannabis users displayed lower activation than non-users in brain regions involved in associative learning, particularly in the (para)hippocampal regions and the right dorsolateral prefrontal cortex, despite normal performance. VBM-analysis of the (para)hippocampal regions revealed no differences in brain tissue composition between cannabis users and non-users. No relation was found between (para)hippocampal tissue composition and the magnitude of brain activity in the (para)hippocampal area. Therefore, lower brain activation may not signify neurocognitive impairment, but could be the expression of a non-cognitive variable related to frequent cannabis use, for example changes in cerebral perfusion or differences in vigilance.

ThePIP5K2AandRGS4genes are differentially associated with deficit and non-deficit schizophrenia

Several putative schizophrenia susceptibility genes have recently been reported, but it is not clear whether these genes are associated with schizophrenia in general or with specific disease subtypes. In a previous study, we found an association of the neuregulin 1 (NRG1) gene with non-deficit schizophrenia only. We now report an association study of four schizophrenia candidate genes in patients with and without deficit schizophrenia, which is characterized by severe and enduring negative symptoms. Single-nucleotide polymorphisms (SNPs) were genotyped in the DTNBP1 (dysbindin), G72/G30 and RGS4 genes, and the relatively unknown PIP5K2A gene, which is located in a region of linkage with both schizophrenia and bipolar disorder. The sample consisted of 273 Dutch schizophrenia patients, 146 of whom were diagnosed with deficit schizophrenia and 580 controls. The strongest evidence for association was found for the A-allele of SNP rs10828317 in the PIP5K2A gene, which was associated with both clinical subtypes (P = 0.0004 in the entire group; non-deficit P = 0.016, deficit P = 0.002). Interestingly, this SNP leads to a change in protein composition. In RGS4, the G-allele of the previously reported SNP RGS4-1 (single and as part of haplotypes with SNP RGS4-18) was associated with non-deficit schizophrenia (P = 0.03) but not with deficit schizophrenia (P = 0.79). SNPs in the DTNBP1 and G72/G30 genes were not significantly associated in any group. In conclusion, our data provide further evidence that specific genes may be involved in different schizophrenia subtypes and suggest that the PIP5K2A gene deserves further study as a general susceptibility gene for schizophrenia.