Empirical validity of Leonhard's psychoses: A long-term follow-up study of first-episode psychosis patients

The validation of nosological diagnoses in psychiatry remains a conundrum. Leonhard's (1979) nosology seems to be one of the few acceptable alternative categorical models to current DSM/ICD systems. We aimed to empirically validate Leonhard's four classes of psychoses: systematic schizophrenia (SSch), unsystematic (USch), cycloid psychosis (Cyclo), and manic-depressive illness (MDI) using a comprehensive set of explanatory validators. 243 patients with first-episode psychosis were followed between 10 and 31 years. A wide-ranging assessment was carried out by collecting data on antecedent, illness-related, concurrent, response to treatment, neuromotor abnormalities, and cognitive impairment variables. Compared with USch, Cyclo, and MDI, SSch displayed a pattern of impairments significantly larger across the seven blocks of explanatory variables. There were no significant differences between Cyclo and MDI in explanatory variables. Except for the majority of illness-onset features, USch displayed more substantial abnormalities in the explanatory variables than Cyclo and MDI. SSch and MDI showed higher percentages of correctly classified patients than USch and Cyclo in linear discriminant analyses. Partial validation of Leonhard's classification was found. SSch showed differences in explanatory variables with respect to Cyclo and MDI. USch showed also significant differences in explanatory variables regarding Cyclo and MDI, although with a lower strength than SSch. There was strong empirical evidence of the separation between both Leonhard's schizophrenia subtypes; however, the distinction between the Cyclo and MDI groups was not empirically supported. A mild to moderate discriminative ability between Leonhard's subtypes on the basis of explanatory blocks of variables was observed.

Effect of polygenic risk score, family load of schizophrenia and exposome risk score, and their interactions, on the long-term outcome of first-episode psychosis

BACKGROUND

Consistent evidence supports the involvement of genetic and environmental factors, and their interactions, in the etiology of psychosis. First-episode psychosis (FEP) comprises a group of disorders that show great clinical and long-term outcome heterogeneity, and the extent to which genetic, familial and environmental factors account for predicting the long-term outcome in FEP patients remains scarcely known.

METHODS

The SEGPEPs is an inception cohort study of 243 first-admission patients with FEP who were followed-up for a mean of 20.9 years. FEP patients were thoroughly evaluated by standardized instruments, with 164 patients providing DNA. Aggregate scores estimated in large populations for polygenic risk score (PRS-Sz), exposome risk score (ERS-Sz) and familial load score for schizophrenia (FLS-Sz) were ascertained. Long-term functioning was assessed by means of the Social and Occupational Functioning Assessment Scale (SOFAS). The relative excess risk due to interaction (RERI) was used as a standard method to estimate the effect of interaction of risk factors.

RESULTS

Our results showed that a high FLS-Sz gave greater explanatory capacity for long-term outcome, followed by the ERS-Sz and then the PRS-Sz. The PRS-Sz did not discriminate significantly between recovered and non-recovered FEP patients in the long term. No significant interaction between the PRS-Sz, ERS-Sz or FLS-Sz regarding the long-term functioning of FEP patients was found.

CONCLUSIONS

Our results support an additive model of familial antecedents of schizophrenia, environmental risk factors and polygenic risk factors as contributors to a poor long-term functional outcome for FEP patients.

Neurocognitive correlates of the varied domains of outcomes at 20 year follow-up of first-episode psychosis

Little is known about long-term outcomes of the first episode of psychosis (FEP) other than in the symptomatic domain. We hypothesised that cognitive impairment is associated with poorer multi-domain outcomes at a long-term follow-up of FEP patients. We followed-up 172 FEP patients for a mean of 20.3 years. Ten outcome dimensions were assessed (symptomatic, functional and personal recovery, social disadvantage, physical health, suicide attempts, number of episodes, current drug use, chlorpromazine equivalent doses (CPZ), and schizophrenia/schizoaffective disorder final diagnosis). Cognition was assessed at follow-up. Processing speed and verbal memory deficits showed significant associations with poor outcomes on symptomatic, social functioning, social disadvantage, higher number of episodes, and higher CPZ. Significant associations were found between visual memory impairments were significantly associated with low symptomatic and functional recovery, between attentional deficits and a final diagnosis of schizophrenia/schizoaffective disorder, and between social cognition deficits and poor personal recovery.Lower cognitive global scores were significantly associated with all outcome dimensions except for drug abuse and physical status. Using multiple outcome dimensions allowed for the inclusion of the patients' perspective and other commonly neglected outcome measures. Taken together, cognitive impairment in FEP patients is strongly related to poor performance on several outcome dimensions beyond symptomatic remission.

Association and epistatic analysis of white matter related genes across the continuum schizophrenia and autism spectrum disorders: The joint effect of NRG1-ErbB genes

BACKGROUND

Schizophrenia-spectrum disorders (SSD) and Autism spectrum disorders (ASD) are neurodevelopmental disorders that share clinical, cognitive, and genetic characteristics, as well as particular white matter (WM) abnormalities. In this study, we aimed to investigate the role of a set of oligodendrocyte/myelin-related (OMR) genes and their epistatic effect on the risk for SSD and ASD.

METHODS

We examined 108 SNPs in a set of 22 OMR genes in 1749 subjects divided into three independent samples (187 SSD trios, 915 SSD cases/control, and 91 ASD trios). Genetic association and gene-gene interaction analyses were conducted with PLINK and MB-MDR, and permutation procedures were implemented in both.

RESULTS

Some OMR genes showed an association trend with SSD, while after correction, the ones that remained significantly associated were MBP, ERBB3, and AKT1. Significant gene-gene interactions were found between (i) NRG1*MBP (perm p-value = 0.002) in the SSD trios sample, (ii) ERBB3*AKT1 (perm p-value = 0.001) in the SSD case-control sample, and (iii) ERBB3*QKI (perm p-value = 0.0006) in the ASD trios sample.

DISCUSSION

Our results suggest the implication of OMR genes in the risk for both SSD and ASD and highlight the role of NRG1 and ERBB genes. These findings are in line with the previous evidence and may suggest pathophysiological mechanisms related to NRG1/ERBBs signalling in these disorders.

The effect of the AKT1 gene and cannabis use on cognitive performance in healthy subjects

BACKGROUND

Evidence suggests that the AKT1 gene may modulate the degree to which cannabis use induces cognitive alterations in patients with a psychotic disorder.

AIM

To examine the interplay between AKT1 and cannabis use in terms of the cognitive performance of the general population.

METHODS

Our sample consisted of 389 Spanish university students. Sustained attention was measured via the Continuous Performance Test-Identical Pairs, immediate and delayed verbal memory with the Logical Memory subtest of the Wechsler Memory Scale, and working memory with the Wisconsin Card Sorting Test. Lifetime cannabis use frequency was assessed and individuals were classified as cannabis users or non-users. Two single nucleotide polymorphisms of the AKT1 gene were genotyped and, according to previous studies, each subject was defined as a carrier of two, one or no copies of the haplotype (rs2494732(C)-rs1130233(A)). Multiple linear regressions were conducted to test the effect of the genetic variability and cannabis use (and their interaction) on cognitive performance.

RESULTS

An effect of the AKT1 haplotype was found on attention scores: individuals with two copies of the haplotype performed better (β=0.18, p<0.001 (adjusted for false discovery rate)), while neither cannabis nor the AKT1-cannabis interaction was associated with attention. No effect of AKT1, cannabis or the AKT1-cannabis interaction was found on verbal memory or working memory.

CONCLUSIONS

Our study provides additional evidence that AKT1 modulates cognitive performance. However, in our non-clinical sample, the previously reported interaction between cannabis use and the AKT1 gene was not replicated.

Effect of DISC1 Polymorphisms on the Long-term Course of Neurocognitive Deficits in Non-affective Psychosis

Neurocognitive deficits are core symptoms of schizophrenia that determine a poorer outcome. High variability in the progression of neuropsychological deficits in schizophrenia has been described. It is still unknown whether genetic variations can affect the course of cognitive deficits. Variations in the Disrupted in Schizophrenia 1 (DISC1) gene have previously been associated with neurocognitive deficits. This study investigated the association between 3 DISC1 polymorphisms (rs6675281 (Leu607Phe), rs1000731, and rs821616 (Ser704Cys)) and long-term (3 years) cognitive performance. One-hundred-thirty-three Caucasian drug-naive patients experiencing a first episode of non-affective psychosis were genotyped. Cognitive function was assessed at baseline and after 3 years of initiating treatment. Other clinical and socio-demographic variables were recorded to eliminate potential confounding effects. Patients carrying the A allele of rs1000731 exhibited a significant improvement in Working Memory and Attention domains, and the homozygosity of the A allele of rs821616 showed a significant improvement in Motor Dexterity performance over 3 years of follow-up. In conclusion, DISC1 gene variations may affect the course of cognitive deficits found in patients suffering from the first episode of non-affective psychosis.

Epigenetic signature of glucocorticoid receptor is associated with the familial component of depression: A twin-based study

Introduction

Despite the fact that depression has an estimated heritability around 40%, there is no definitive candidate gene contributing to its etiology. The lack of an identified genetic component for high-heritability disorders, like depression, gave rise to the concept of missing heritability. The epigenetics’ field has pushed forward new hypotheses to fill this gap since transgenerational inheritance of epigenetic patterns has been described both in animal models and, more recently, in humans. Depression is usually associated with an abnormal stress response and an altered hypothalamic-pituitary-adrenal axis, regulated by the glucocorticoid receptor (coded by NR3C1 gene). Therefore, NR3C1 has been widely investigated as a functional candidate gene involved in anxious-depressive spectrum disorders (ADSD) although a more comprehensive study of its methylation is further required (Palma-Gudiel et al., 2015).

Aims

To analyze NR3C1 promoter's methylation and to study its association with anxious-depressive spectrum disorders.

Methods

The sample consisted of 48 pairs of monozygotic twins, from the UB twin register, grouped as concordant, discordant and healthy pairs depending on whether both, one or none of the co-twins of each pair were affected by a lifetime ADSD, according to DSM-IV criteria (SCID). DNA methylation was assessed by bisulfite conversion and subsequent pyrosequencing.

Results

Hypermethylation at specific CpG sites, not previously reported, was detected in concordant twin pairs as compared with discordant and healthy groups (P = 0.03).

Conclusions

The epigenetic pattern newly described in NR3C1 gene may be contributing to the familial component of depression and thus could be putatively explained by transgenerational inheritance of epigenetic phenomena.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Influence of DAOA and RGS4 genes on the risk for psychotic disorders and their associated executive dysfunctions: A family-based study

Background

Glutamatergic neurotransmission dysfunction has classically been related to the aetiology of psychotic disorders. A substantial polygenic component shared across these disorders has been reported and molecular genetics studies have associated glutamatergic-related genes, such as d-amino acid oxidase activator (DAOA) and regulator of G-protein signalling 4 (RGS4) with the risk for psychotic disorders. Our aims were to examine: (i) the relationship between DAOA and RGS4 and the risk for psychotic disorders using a family-based association approach, and (ii) whether variations in these genes are associated with differences in patients’ cognitive performance.

Methods

The sample comprised 753 subjects (222 patients with psychotic disorders and 531 first-degree relatives). Six SNPs in DAOA and 5 SNPs in RGS4 were genotyped. Executive cognitive performance was assessed with Trail Making Test B (TMT-B) and Wisconsin Card Sorting Test (WCST). Genetic association analyses were conducted with PLINK, using the transmission disequilibrium test (TDT) for the family-based study and linear regression for cognitive performance analyses.

Results

The haplotype GAGACT at DAOA was under-transmitted to patients (P = 0.0008), indicating its association with these disorders. With regards to cognitive performance, the DAOA haplotype GAGGCT was associated with worse scores in TMT-B (P = 0.018) in SZ patients only. RGS4 analyses did not report significant results.

Conclusions

Our findings suggest that the DAOA gene may contribute to the risk for psychotic disorders and that this gene may play a role as a modulator of executive function, probably through the dysregulation of the glutamatergic signalling.

The role of schizotypal traits and the OXTR gene in theory of mind in schizophrenia: A family-based study

BACKGROUND

There is consistent evidence that theory of mind (ToM) is impaired in schizophrenia (SZ); however, it remains unclear whether such deficits are trait- or state-dependent. We evaluated ToM in patients with schizophrenia spectrum disorders (SSDs), their healthy first-degree relatives, and controls to test its suitability as an endophenotypic marker. We also studied the modifying effect of markers of clinical and genetic liability to SZ (schizotypy and genetic variability in the oxytocin receptor gene: OXTR) on ToM in healthy individuals.

METHODS

The sample included 38 stable SSD patients, 80 unaffected first-degree relatives, and 81 controls. ToM was assessed using the Hinting Task (HT) and schizotypy via the Schizotypal Personality Questionnaire-Brief (SPQ-B), which generates interpersonal (SPQ-IP), cognitive-perceptual (SPQ-CP), and disorganization (SPQ-D) scores. The polymorphism rs53576 of OXTR was genotyped.

RESULTS

Patients presented poorer HT performance than relatives and controls (p = 0.003 and p < 0.001). High SPQ-IP and SPQ-CP scores correlated with poorer ToM performance in relatives (p = 0.010 and p = 0.030), but not in controls. OXTR was not associated with HT scores, but it showed a modifying effect within controls; high SPQ-CP was related to HT poorer performance conditional to GG genotype (p = 0.007).

CONCLUSIONS

ToM deficits were present in patients but not in unaffected relatives or controls. However, our data indicate the usefulness of clinical and genetic liability markers to characterize differences in ToM abilities within healthy individuals. Then, the observed link between ToM and SZ liability suggests the putative role of ToM as an endophenotypic marker. Nevertheless, new analyses in larger samples are needed.

The synergetic effect of childhood trauma and recent stressful events in psychosis: associated neurocognitive dysfunction

BACKGROUND

A higher incidence of childhood trauma (CT) has been reported in first episode of psychosis (FEP). There is, however, a lack of knowledge about the synergetic effect between CT and recent stressful events (RSE).

METHODS

Information on specific types of CT (under 17 years) and RSE (within the past 3 years) was available for 290 FEP patients and 52 healthy controls (HC). Cognitive function at baseline was assessed through a comprehensive neuropsychological test battery.

RESULTS

While 45.2% of FEP patients and 25% of HC reported at least one CT event, 62.7% of FEP and 21.2% of HC reported an RSE. Meanwhile, 36.2% of FEP patients and 9.6% of HC encountered both childhood and recent stressful events. The patients that just reported CT showed normality in all but the verbal memory cognitive domain; those with additive CT and RSE presented worse general cognitive function, specifically on working memory, processing speed, and executive function. RSE and general cognitive dysfunction were significant determinants of psychosis onset.

CONCLUSIONS

These results support a synergetic influence of trauma and stressful events on brain function and allow a better understanding of mediators for psychotic disorders useful in the design of specific strategies based on stress-targeted therapies.

Neurotrophins role in depressive symptoms and executive function performance: Association analysis of NRN1 gene and its interaction with BDNF gene in a non-clinical sample

BACKGROUND

Neuritin-1 is a neurotrophic factor involved in synaptic plasticity that has been associated with depressive disorders, schizophrenia and cognitive performance. The study of genotype-phenotype relationships in healthy individuals is a useful framework to investigate the etiology of brain dysfunctions. We therefore aimed to investigate in a non-clinical sample whether NRN1 gene contributes to the psychopathological profile, with a particular focus on the clinical dimensions previously related to the NRN1 gene (i.e. depressive and psychotic). Furthermore, we aimed to analyze: i) the role of NRN1 on executive functions, ii) whether the association between either NRN1-psychopathological profile or NRN1-cognitive performance is moderated by the BDNF gene.

METHODS

The sample comprised 410 non-clinical subjects who filled in the self-reported Brief Symptom Inventory (BSI) and were assessed for executive performance (Verbal Fluency, Wisconsin Card Sorting Test (WCST) and Letter-Number subscale (WAIS-III)). Genotyping included nine SNPs in NRN1 and one in BDNF.

RESULTS

i) GG homozygotes (rs1475157-NRN1) showed higher scores on BSI depressive dimension and on total scores compared to A carriers (corrected p-values: 0.0004 and 0.0003, respectively). ii) a linear trend was detected between GG genotype of rs1475157 and a worse cognitive performance in WCST total correct responses (uncorrected p-value: 0.029). iii) Interaction between rs1475157-NRN1 and Val66Met-BDNF was found to modulate depressive symptoms (p=0.001, significant after correction).

LIMITATIONS

Moderate sample size; replication in a larger sample is needed.

CONCLUSIONS

NRN1 is associated with depressive symptoms and executive function in a non-clinical sample. Our results also suggest that the role of NRN1 seems to be modulated by BDNF.

Familial aggregation of schizotypy in schizophrenia-spectrum disorders and its relation to clinical and neurodevelopmental characteristics

INTRODUCTION

This study explored schizotypy as a familial liability marker for schizophrenia-spectrum disorders (SSD) by examining: 1) the aggregation of schizotypy in families with a SSD patient, 2) whether familial resemblance of schizotypy is associated with ridge dissociations (RD), another SSD liability marker, 3) whether schizotypy aggregation patterns influence patients' psychopathology.

METHODS

The sample comprised 30 SSD patients and 82 healthy first-degree relatives. Schizotypy was assessed using the Structured Interview for Schizotypy-Revised (SIS-R). Patients' psychopathology was evaluated using the Comprehensive Assessment of Symptoms and History (CASH). RD were identified as anomalies of the dermal ridge junction. Familiality of SIS-R was investigated using a linear mixed model (LMM) and its strength was assessed using an intraclass correlation coefficient (ICC). Another LMM using the absolute differences in SIS-R scores between all possible pairs of relatives as the dependent variable was fitted to obtain an intra-family resemblance score, a family-specific indicator of resemblance of SIS-R scores within each family.

RESULTS

1) Schizotypy was familial (ICC = 0.30); families with high resemblance displayed low schizotypy, whereas families with low resemblance included at least one healthy relative with high schizotypy (p < 0.001). 2) Relatives with RD had higher SIS-R scores (p = 0.018) and belonged to families with discordant schizotypy scores among members (p < 0.001). 3) Patients from high schizotypy families showed more severe disorganized symptoms at the psychotic episode (p = 0.035) and 1 year later (p = 0.011).

CONCLUSIONS

Schizotypy is a marker of vulnerability for SSD that runs within a subgroup of families. The schizotypy familial aggregation pattern correlates with RD in relatives and with patients' psychopathology.

Evidence of an epistatic effect between Dysbindin-1 and Neuritin-1 genes on the risk for schizophrenia spectrum disorders

BACKGROUND

The interest in studying gene-gene interactions is increasing for psychiatric diseases such as schizophrenia-spectrum disorders (SSD), where multiple genes are involved. Dysbindin-1 (DTNBP1) and Neuritin-1 (NRN1) genes have been previously associated with SSD and both are involved in synaptic plasticity. We aimed to study whether these genes show an epistatic effect on the risk for SSD.

METHODS

The sample comprised 388 SSD patients and 397 healthy subjects. Interaction was tested between: (i) three DTNBP1 SNPs (rs2619537, rs2743864, rs1047631) related to changes in gene expression; and (ii) an haplotype in NRN1 previously associated with the risk for SSD (rs645649-rs582262: HAP-risk C-C).

RESULTS

An interaction between DTNBP1 rs2743864 and NRN1 HAP-risk was detected by using the model based multifactor dimensionality reduction (MB-MDR) approach (P=0.0049, after permutation procedure), meaning that the risk for SSD is significantly higher in those subjects carrying both the A allele of rs2743864 and the HAP-risk C-C. This interaction was confirmed by using a logistic regression model (P=0.033, OR (95%CI)=2.699 (1.08-6.71), R²=0.162).

DISCUSSION

Our results suggest that DTNBP1 and NRN1 genes show a joint effect on the risk for SSD. Although the precise mechanism underlying this effect is unclear, the fact that these genes have been involved in synaptic maturation, connectivity and glutamate signalling suggests that our findings could be of value as a link to the schizophrenia aetiology.

Maternal psychosocial stress during pregnancy alters the epigenetic signature of the glucocorticoid receptor gene promoter in their offspring: a meta-analysis

Prenatal stress has been widely associated with a number of short- and long-term pathological outcomes. Epigenetic mechanisms are thought to partially mediate these environmental insults into the fetal physiology. One of the main targets of developmental programming is the hypothalamic-pituitary-adrenal (HPA) axis as it is the main regulator of the stress response. Accordingly, an increasing number of researchers have recently focused on the putative association between DNA methylation at the glucocorticoid receptor gene (NR3C1) and prenatal stress, among other types of psychosocial stress. The current study aims to systematically review and meta-analyze the existing evidence linking several forms of prenatal stress with DNA methylation at the region 1F of the NR3C1 gene. The inclusion of relevant articles allowed combining empirical evidence from 977 individuals by meta-analytic techniques, whose methylation assessments showed overlap across 5 consecutive CpG sites (GRCh37/hg19 chr5:142,783,607-142,783,639). From this information, methylation levels at CpG site 36 displayed a significant correlation to prenatal stress (r = 0.14, 95% CI: 0.05-0.23, P = 0.002). This result supports the proposed association between a specific CpG site located at the NR3C1 promoter and prenatal stress. Several confounders, such as gender, methylation at other glucocorticoid-related genes, and adjustment for pharmacological treatments during pregnancy, should be taken into account in further studies.

Methylome modifications in monozygotic twins and in depression

Epigenetics is the study of gene expression changes that are produced by heritable, though potentially reversible, modifications of chromatin structure or DNA methylation. DNA methylation is interesting in epidemiological studies, due to its accessibility and since previous evidence indicates that large inter-individual differences in methylation levels at some loci may correlate with phenotypic plasticity in changing environments.

Prior genome-wide methylomic research on depression has suggested that, together with differential DNA methylation changes, affected co-twins of monozygotic twin pairs have increased DNA methylation variability, probably in line with theories of epigenetic stochasticity. However, the putative biological roots of this variability remain largely unexplored.

This study evaluate whether DNA methylation differences within MZ twin pairs were related to differences in their depressive status. Genome-wide DNA methylation levels were measured in peripheral blood of 34 twins (17 MZ pairs) using Illumina Infinium Human Methylation450 Beadchip. Two analytical strategies were used to identify differentially methylated probes (DMPs) and variably methylated probes (VMPs).

The majority of the DMPs were located in genes previously related to neuropsychiatric phenotypes, such as WDR26, a GWAS hit for MDD whose expression levels have been found altered in blood of depressed individuals.

VMPs were located in genes such as CACNA1C, IGF2 and the p38 MAP kinase MAPK11, showing enrichment for biological processes such as glucocorticoid signaling.

The findings expand on previous research to indicate that both differential and variable methylation may play a role in the etiopathology of depression, and suggest specific genomic loci of potential interest in the epigenetics of depression.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Further evidence of DEPDC7 DNA hypomethylation in depression: A study in adult twins

Late and early stressful factors have widely been recognized to play a role in the aetiology of depression. Recent research indicates that such adverse environmental stimuli may alter gene expression in humans via epigenetic modifications. While epigenetic changes such as DNA methylation are likely involved in these processes, it is still unknown what specific genomic loci may be hyper- or hypo-methylated in depression. The association between depressive symptoms during the last 30 days (Brief Symptom Inventory [BSI]) and peripheral-blood DNA methylation levels at genomic loci previously reported as epigenetically altered in saliva and brain of depressive patients was evaluated in a community sample of 34 adult Caucasian MZ twins (17 pairs). Intrapair DNA methylation differences in an intron of DEPDC7 (chr11:33040743) were associated with intrapair differences in current depressive symptoms. Accordingly, a site-specific 10% DNA hypomethylation in a co-twin would correlate with a current depressive symptom score around 3.1 BSI points above the score of his/her less-depressed co-twin. These findings indicate that DEPDC7 hypomethylation in peripheral blood DNA may be associated with recent depressive symptomatology, in line with previous results.

Polymorphic variation in the epigenetic gene DNMT3B modulates the environmental impact on cognitive ability: a twin study

BACKGROUND

Though cognitive abilities in adulthood are largely influenced by individual genetic background, they have also been shown to be importantly influenced by environmental factors. Some of these influences are mediated by epigenetic mechanisms. Accordingly, polymorphic variants in the epigenetic gene DNMT3B have been linked to neurocognitive performance. Since monozygotic (MZ) twins may show larger or smaller intrapair phenotypic differences depending on whether their genetic background is more or less sensitive to environmental factors, a twin design was implemented to determine if particular polymorphisms in the DNMT3B gene may be linked to a better (worse) response to enriched (deprived) environmental factors.

METHODS

Applying the variability gene methodology in a sample of 54 healthy MZ twin pairs (108 individuals) with no lifetime history of psychopathology, two DNMT3B polymorphisms were analyzed in relation to their intrapair differences for either intellectual quotient (IQ) or working memory performance.

RESULTS

MZ twin pairs with the CC genotype for rs406193 SNP showed statistically significant larger intrapair differences in IQ than CT pairs.

CONCLUSIONS

Results suggest that DNMT3B polymorphisms may explain variability in the IQ response to either enriched or impoverished environmental conditions. Accordingly, the applied methodology is shown as a potentially valuable tool for determining genetic markers of cognitive plasticity. Further research is needed to confirm this specific result and to expand on other putative genetic markers of environmental sensitivity.

Childhood abuse in the etiological continuum underlying psychosis from first-episode psychosis to psychotic experiences

GOAL

The present study aimed to examine the prevalence of child abuse across the continuum of psychosis.

PATIENTS AND METHODS

The sample consisted of 198 individuals divided in three groups: (1) 48 FEP patients, (2) 77 individuals scoring high in Community Assessment of Psychic Experiences (CAPE), classified as "High CAPE" group and (3) 73 individuals scoring low, classified as "Low CAPE" group. Childhood abuse was assessed using self-report instruments. Chi(2) tests and logistic regression models controlling by sex, age and cannabis were used to perform three comparisons: (i) FEP vs. Low CAPE; (ii) FEP vs. High CAPE and (iii) High CAPE vs. Low CAPE.

RESULTS

The frequency of individuals exposed to childhood abuse for FEP, High CAPE and Low CAPE groups were 52.1%, 41.6% and 11%, respectively. FEP and High CAPE group presented significantly higher rates of childhood abuse compared to Low CAPE group, however, no significant differences were found between FEP and High CAPE groups regarding the frequency of childhood abuse.

CONCLUSION

There is an increasing frequency of childhood abuse from low subclinical psychosis to FEP patients. However, childhood abuse is equally common in FEP and at risk individuals.

Cortical thickness correlates of psychotic experiences: examining the effect of season of birth using a genetically informative design

Season of birth has been shown to influence risk for several neuropsychiatric diseases. Furthermore, it has been suggested that season of birth modifies a number of brain morphological traits. Since cortical thickness alterations have been reported across some levels of the psychosis-spectrum, this study was aimed at i) assessing the scarcely explored relationship between cortical thickness and severity of subclinical psychotic experiences (PEs) in healthy subjects, and ii) evaluating the potential impact of season of birth in the preceding thickness-PEs relationship. As both PEs and brain cortical features are heritable, the current work used monozygotic twins to separately evaluate familial and unique environmental factors. High-resolution structural MRI scans of 48 twins (24 monozygotic pairs) were analyzed to estimate cortical thickness using FreeSurfer. They were then examined in relation to PEs, accounting for the effects of birth season; putative differential relationships between PEs and cortical thickness depending on season of birth were also tested. Current results support previous findings indicative of cortical thickening in healthy individuals with high psychometrically assessed psychosis scores, probably in line with theories of compensatory aspects of brain features in non-clinical populations. Additionally, they suggest distinct patterns of cortical thickness-PEs relationships depending on birth seasonality. Familial factors underlying the presence of PEs may drive these effects.

The BDNF-Val66Met polymorphism modulates parental rearing effects on adult psychiatric symptoms: a community twin-based study

PURPOSE

To test whether firstly, different parental rearing components were associated with different dimensions of psychiatric symptoms in adulthood, secondly BDNF-Val66Met polymorphism moderated this association and thirdly, this association was due to genetic confounding.

METHOD

Perceived parental rearing according to Parental Bonding Instrument (PBI), psychiatric symptoms evaluated with the Brief Symptom Inventory (BSI) and the BDNF-Val66Met polymorphism were analyzed in a sample of 232 adult twins from the general population.

RESULTS

In the whole sample, paternal care was negatively associated with depression. Maternal overprotection was positively associated with paranoid ideation, obsession-compulsion and somatization. Gene-environment interaction effects were detected between the BDNF-Val66Met polymorphism and maternal care on phobic anxiety, paternal care on hostility, maternal overprotection on somatization and paternal overprotection also in somatization. In the subsample of MZ twins, intrapair differences in maternal care were associated with anxiety, paranoid ideation and somatization.

CONCLUSIONS

Met carriers were, in general, more sensitive to the effects of parental rearing compared to Val/Val carriers in relation to anxiety and somatization. Contra-intuitively, our findings suggest that high rates of maternal care might be of risk for Met carriers regarding anxiety. Results from analyses controlling for genetic confounding were in line with this finding.

Psychosis-inducing effects of cannabis are related to both childhood abuse and COMT genotypes

OBJECTIVE

To test whether the association between childhood abuse, cannabis use and psychotic experiences (PEs) was moderated by the COMT (catechol-O-methyltransferase) gene.

METHOD

Psychotic experiences (PEs), childhood abuse, cannabis use and COMT Val158Met genotypes were assessed in 533 individuals from the general population. Data were analysed hierarchically by means of multiple linear regression models.

RESULTS

Childhood abuse showed a significant main effect on both positive (β = 0.09; SE = 0.04; P = 0.047) and negative PEs (β = 0.11; SE = 0.05; P = 0.038). A significant three-way interaction effect was found among childhood abuse, cannabis use and the COMT gene on positive PEs (β = -0.30; SE = 0.11; P = 0.006). This result suggests that COMT genotypes and cannabis use only influenced PE scores among individuals exposed to childhood abuse. Furthermore, exposure to childhood abuse and cannabis use increased PE scores in Val carriers. However, in individuals exposed to childhood abuse but who did not use cannabis, PEs increased as a function of the Met allele copies of the COMT gene.

CONCLUSION

Cannabis use after exposure to childhood abuse may have opposite effects on the risk of PEs, depending on the COMT genotypes providing evidence for a qualitative interaction. Val carriers exposed to childhood abuse are vulnerable to the psychosis-inducing effects of cannabis.

Childhood adversity and psychosis: Examining whether the association is due to genetic confounding using a monozygotic twin differences approach

Purpose

To test whether the association between childhood adversity and positive and negative psychotic experiences is due to genetic confounding.

Method

Childhood adversity and psychotic experiences were assessed in an ongoing sample of 226 twins from the general population. A monozygotic (MZ) twin differences approach was used to assess possible genetic confounding.

Results

In the whole sample, childhood adversity was significantly associated with positive (β = 45; SE = 0.16; P = 0.008) and negative psychotic experiences (β = 0.77; SE = 0.18; P < 0.01). Within-pair MZ twin differences in exposure to childhood adversity were significantly associated with differences in positive (β = 71; SE = 0.29; P = 0.016) and negative psychotic experiences (β = 98; SE = 0.38; P = 0.014) in a subsample of 85 MZ twin pairs.

Conclusions

Individuals exposed to childhood adversity are more likely to report psychotic experiences. Furthermore, our findings indicate that this association is not due to genetic confounding.

The role of genetic variability in the SLC6A4, BDNF and GABRA6 genes in anxiety-related traits

OBJECTIVE

The aims of this study were to test the individual association of the serotonin transporter gene (SLC6A4), the brain-derived neurotrophic factor gene (BDNF) and the GABA(A) α(6) receptor subunit gene (GABRA6) with anxiety-related traits and to explore putative gene-gene interactions in a Spanish healthy sample.

METHOD

A sample of 937 individuals from the general population completed the Temperament and Character Inventory questionnaire to explore Harm Avoidance (HA) dimension; a subsample of 553 individuals also filled in the Big Five Questionnaire to explore the Neuroticism dimension. The whole sample was genotyped for the 5-HTTLPR polymorphism (SLC6A4 gene), the Val66Met polymorphism (BDNF gene) and the T1521C polymorphism (GABRA6 gene).

RESULTS

Homozygous individuals for the T allele of the T1512C polymorphism presented slightly higher scores for HA than C allele carriers (F = 2.96, P = 0.019). In addition, there was a significant gene-gene interaction on HA between the 5-HTTLPR and Val66Met polymorphisms (F = 3.4, P = 0.009).

CONCLUSION

GABRA6 emerges as a candidate gene involved in the variability of HA. The effect of a significant gene-gene interaction between the SLC6A4 and BDNF genes on HA could explain part of the genetic basis underlying anxiety-related traits.

Impulsivity and functional impairment in bipolar disorder

BACKGROUND

Impulsivity is substantially higher in bipolar patients (BP) and may be associated with a more severe course of illness, but no studies have so far examined the relationship between impulsivity and functional outcome in BP. Our goal was to investigate the functional impact of trait-impulsivity in BP.

METHODS

138 euthymic BP were recruited. All patients were assessed using an interview based on the Structured Clinical Interview for DSM Disorders (SCID). The Functioning Assessment Short Test (FAST) and the Barratt Impulsiveness Scale (BIS-11) were used to assess functional outcome and impulsivity, respectively. Seven multiple linear regressions, with each individual FAST subscale scores and overall FAST score as dependant variables, were conducted in order to evaluate the predictive role of trait-impulsivity on functional outcome.

RESULTS

After a multiple linear regression model, with the FAST total score as dependent variable, we found that depressive symptoms (β=1.580; p<0.001), number of hospitalizations (β=0.837; p=0.019) and impulsivity (β=0.319; p=0.004) were independently associated with overall functional impairment (F=6.854, df=9, p<0.001, adjusted R2=0.311).

LIMITATIONS

The cross-sectional design of the study.

CONCLUSIONS

Our results indicate that impulsivity, as well as depressive symptoms and the number of hospitalizations, is associated with overall functional impairment in BP. The assessment and treatment of impulsivity may be useful in improving functional outcome in BP.

Neurodevelopmental liability to schizophrenia: the complex mediating role of age at onset and premorbid adjustment

Large individual variation in the clinical presentation of schizophrenia-spectrum disorders raises key questions regarding their aetiological underpinnings. In this respect, age at onset of the disorder is a particularly interesting marker of liability, as it has been reported to be associated with other signs of developmental compromise, such as male gender, increased presence of familial history of psychosis and poor premorbid adjustment, as well as a more severe clinical outcome in terms of cognition and symptomatology. The association between these variables has encouraged a neurodevelopmental perspective of the aetiological mechanisms involved in the pathophysiology of schizophrenia. However, the complex relationships within neurobiological liability markers, and between these markers and clinical outcome, remain to be understood. In the present study, we used a path-analytic approach to explore: i) the fit of the model to observed data; and both ii) direct and iii) indirect associations between the variables. In a sample of 106 patients with schizophrenia-spectrum disorders, we found a good fit of the model to the observed data, providing further evidence that supports a neurodevelopmental pathway to the disease in a subgroup of patients. However, the most parsimonious model showed complex relationships, where age at onset and premorbid functioning acted as mediators between gender, familial history of psychosis and clinical outcome. These findings refine earlier explanations of the neurobiological basis of schizophrenia, with potential applications in genetic studies based on more homogeneous forms of the disease. We further discuss the putative implications of our results in clinical practice and prevention policies.

Cannabis use and age at onset of psychosis: further evidence of interaction with COMT Val158Met polymorphism

OBJECTIVE

To examine, in a sample of young psychiatric patients, (n = 157, mean age 17.01 years (SD = 3.6)) whether i) age at first cannabis use and age at emergence of psychiatric disorders are related and ii) such a relationship is modulated by the Val158Met polymorphism in the COMT gene.

METHOD

Cannabis use profiles and COMT Val158Met genotypes were obtained from 80 inpatients with schizophrenia-spectrum disorders and 77 inpatients with other non-psychotic disorders.

RESULTS

First, age at first cannabis use correlates with age at onset in both schizophrenia-spectrum and other psychiatric disorder groups: those who started using cannabis earlier had an earlier age at onset of psychiatric disorders. Second, the distribution of the Val158Met genotypes was not different either between diagnosis groups or between cannabis users and non-users. Third, an interaction between Val158Met genotypes and cannabis use was observed specifically on age at emergence of psychotic disorders, with Val/Val genotype carriers showing an earlier age at onset than Met carriers.

CONCLUSION

Our results suggest the importance of brain maturation timing in which exposure to cannabis occurs. The COMT Val158Met genotype seems to modulate the association between cannabis and age at onset of psychotic disorders. These results are consistent with previous studies.

COMT Val158Met polymorphism in relation to activation and de-activation in the prefrontal cortex: A study in patients with schizophrenia and healthy subjects

The Val158Met polymorphism in the COMT gene has been found to be associated with differences in brain activation in both healthy subjects and patients with schizophrenia. The predominant finding has been increased prefrontal activation associated with the Val allele; however, genotype-related de-activations have not been studied. In this study 42 schizophrenia patients and 31 controls underwent fMRI while performing the n-back task. Brain differences related to presence/absence of disease and presence/absence of the Val/Val genotype were examined. Both disease and Val/Val genotype were associated with failure of de-activation in a cluster centred in the medial prefrontal cortex. There was no interaction between disease and genotype at this location, but clusters where there were significant interactions emerged in the right prefrontal cortex and left temporal/parietal cortex. These findings suggest that Val158Met polymorphism influences task-related de-activations in the default mode network in both healthy subjects and schizophrenia patients to an equivalent extent. However the Val158Met polymorphism also has disease-specific effects on DLPFC activation in schizophrenia.

Early adversity and 5-HTT/BDNF genes: new evidence of gene-environment interactions on depressive symptoms in a general population

BACKGROUND

Adverse childhood experiences have been described as one of the major environmental risk factors for depressive disorder. Similarly, the deleterious impact of early traumatic experiences on depression seems to be moderated by individual genetic variability. Serotonin transporter (5-HTT) and brain-derived neurotrophic factor (BDNF) modulate the effect of childhood adversity on adult depression, although inconsistencies across studies have been found. Moreover, the gene x environment (GxE) interaction concerning the different types of childhood adversity remains poorly understood. The aim of this study was to analyse the putative interaction between the 5-HTT gene (5-HTTLPR polymorphism), the BDNF gene (Val66Met polymorphism) and childhood adversity in accounting for adult depressive symptoms.

METHOD

A sample of 534 healthy individuals filled in self-report questionnaires of depressive symptomatology [the Symptom Check List 90 Revised (SCL-90-R)] and different types of childhood adversities [the Childhood Trauma Questionnaire (CTQ)]. The 5-HTTLPR polymorphism (5-HTT gene) and the Val66Met polymorphism (BDNF gene) were genotyped in the whole sample.

RESULTS

Total childhood adversity (beta=0.27, p<0.001), childhood sexual abuse (CSA; beta=0.17, p<0.001), childhood emotional abuse (beta=0.27, p<0.001) and childhood emotional neglect (beta=0.22, p<0.001) had an impact on adult depressive symptoms. CSA had a greater impact on depressive symptoms in Met allele carriers of the BDNF gene than in the Val/Val group (F=5.87, p<0.0001), and in S carriers of the 5-HTTLPR polymorphism (5-HTT gene) (F=5.80, p<0.0001).

CONCLUSIONS

Childhood adversity per se predicted higher levels of adult depressive symptoms. In addition, BDNF Val66Met and 5-HTTLPR polymorphisms seemed to moderate the effect of CSA on adult depressive symptoms.

Putative role of the COMT gene polymorphism (Val158Met) on verbal working memory functioning in a healthy population

Working memory has been described as a neurocognitive probe of prefrontal brain functioning. Genetic variability related with catechol-O-methyltransferase (COMT) gene (Val158Met polymorphism) has received increasing attention as a possible modulator of working memory tasks in both schizophrenic patients and healthy subjects, although inconsistencies across studies have been found. This may be related to the existence of different working memory components, processes and modalities, which may have different sensitivities to subtle changes in dopamine levels and, therefore, the effect of the underlying COMT Val158Met genetic variability. To test this out a large sample of 521 healthy individuals from the general population were tested on the WCST and three working memory tasks that cover the assessment of verbal and spatial working modalities as well as different components and processes (Letter and Number Sequencing, CPT-IP, Backwards Visual Span). All individuals were genotyped for the rs4680 (Val158Met) polymorphism at the COMT gene. Met carriers showed near-significant better performance in the LNS compared with Val/Val individuals (F = 3.9, df = 1, P = 0.046). Moreover, the analysis for linear trend found that Met allele carriers showed significantly better performance than Val/Val individuals (B = 0.58 P = 0.031), although evidence for a linear trend was not found. None of the WCST indices differed among genotypes. Consistent with the hypothesis that Val158Met polymorphism (COMT gene) might account for individual differences on dopamine-dependent prefrontally related neurocognitive functions, the Letter-Number Sequencing task, which requires not only maintenance but also active manipulation of information seemed to be more sensitive to the disadvantageous Val/Val genotype in a large non-clinical sample.

New evidences of gene and environment interactions affecting prenatal neurodevelopment in schizophrenia-spectrum disorders: a family dermatoglyphic study

BACKGROUND

Several studies have reported an increase of dermatoglyphic anomalies in schizophrenic patients compared to controls. However, the recognition of specific dermatoglyphic variables related to this disorder and their genetic and/or environmental component are still controversial.

METHOD

We conducted a dermatoglyphic analysis in a new sample of 617 individuals: 205 patients with schizophrenia-spectrum disorders, 224 healthy first degree relatives and 188 healthy controls. The dermatoglyphic variables studied were: the total a-b ridge count (TABRC) and its fluctuating asymmetry (FAABRC), and the presence of ridge dissociations (RD) and abnormal palmar flexion creases (APFC).

RESULTS

Patients, relatives and controls did not differ in TABRC. However, within the patients group those with a low birth weight or absence of psychiatric family history showed lower TABRC than the others. The frequency of ectodermic derivates abnormalities (RD and/or APFC) appeared to be higher in patients and relatives than in controls, while first degree relatives did not differ from patients. Males showed an increased rate of ectodermic derivates abnormalities compared to females in all groups and male patients also presented higher FAABRC than female patients.

CONCLUSIONS

Our results suggest a different relative weight of genetic and environmental factors on each dermatoglyphic variable analyzed: i) TABRC may be a sensitive marker to environmental factors in schizophrenia, ii) ectodermal derivates abnormalities appear to be influenced by genetic risk factors, which could be involved both in the disrupted development of ectodermic derivates like dermatoglyphics and central nervous system and in the vulnerability for schizophrenia.

Family-based association study of neuregulin-1 gene and psychosis in a Spanish sample

Neuregulin 1 (NRG1) is one of the most exciting candidate genes for schizophrenia since its first association with the disorder in an Icelandic population. Since then, many studies have analyzed allele and haplotype frequencies in European and Asian populations in cases and controls yielding varying results. We investigated the association of NRG1 with psychosis in a total sample set of 575 individuals from 151 Spanish nuclear families. We tested eight SNPs across 1.2 Mb along NRG1 including regions previously associated to schizophrenia in association studies. After correction for multiple testing, the TDT analysis for each marker did not show a significant over-transmission of alleles from the parents to the affected offspring for any of the markers (P > 0.05). The haplotypic analysis with TRANSMIT and PDT did not show preferential transmission for any of the haplotypes analyzed in our sample. These results do not seem to suggest that the investigated NRG1 markers play a role in schizophrenia in the Spanish population, although the finding of a trend for association with one SNP in the 3'of the gene warrants further investigation.

Dermatoglyphic profile in 22q deletion syndrome

A genetic subtype of schizophrenia has been described in 22q11 Deletion syndrome. Previous studies have described an excess of dermatoglyphic alterations in schizophrenia, such as low a-b ridge counts (ABRCs), a high frequency of ridge dissociations, and increased dermatoglyphic fluctuating asymmetry. Little is known however, about the dermatoglyphic profile of 22qDS subjects showing psychotic symptoms and its similarity to the previously reported anomalies in schizophrenia. We studied the palmar dermatoglyphics of 22 subjects with 22qDS of predominantly Caucasian origin, 15 of whom had psychotic illness, and in 84 healthy controls of similar ethnicity. We observed higher values for total ATD angle in cases than in controls (P = 0.04). In addition, there was an excess of radial figures in the hypothenar area in cases, especially in the left hand. Interestingly, greater fluctuating asymmetry, determined by the absolute difference between right and left ABRC, was observed in 22qDS subjects compared to controls (P = 0.05). However, no differences were found for ABRCs and frequency of dissociations. Despite the small sample size, the palmprints analyzed suggest the existence of an altered dermatoglyphic profile in 22qDS, involving: (i) ATD angle amplitude, (ii) presence of radial loops in the hypothenar area, and (iii) an increment of fluctuating asymmetry. The first two features are similar to those found in other genetic syndromes associated with low IQ, while high levels of fluctuating asymmetry have often been reported in schizophrenia.

[Genetic foundations of vulnerability to depression]

Depression is a complex phenotype probably heterogeneous in its biology and in its aetiology. Genetic studies have contributed to clarifying some aspects of that heterogeneity, but we are still far from being able to establish its molecular foundations, although a certain degree of genetic variability in genes of the serotoninergic system appear to contribute to the risk of the disease and to certain of its clinical aspects. The risk of a major depressive episode increases in relation to the number of genes shared with an affected person but, in genetic terms and given the differential risks found, there is also a certain overlap with bipolar disorder and schizophrenia. These data lead to reflection on the meaning of genetic risk detected in families and its specificity. Perhaps genetic studies will have to leave the categorical definition of phenotypes and begin to use the dimensions of psychopathology for delimiting the biological and genetic subgroups present in functional psychoses.

The 5-HT(2A) receptor gene 102T/C polymorphism is associated with suicidal behavior in depressed patients

Several lines of evidence suggest that genetic factors constitute an important determinant of suicidal behavior. A significant association between the 5-HT(2A)-C allele and suicidality has recently been reported. The aim of this study was to investigate whether the proposed association between 5-HT(2A)-102T/C polymorphism and suicidality could be replicated in a larger and independent sample of Spanish patients with major depression. The 102T/C polymorphism of the 5-HT(2A) receptor gene was analyzed in 159 patients with major depression (DSM-IV criteria) and 164 unrelated and healthy controls using a case control design. All individuals were subjects of Spanish origin. Significant differences in allele (chi-square = 4.13, df = 1, P = 0.04) and genotype (chi-square = 6.19, df = 2, P = 0.04) distributions were found between non-suicide attempters and suicide attempters. Moreover, those patients carrying 5-HT(2A)-C allele had more than five times the risk for attempting suicide than noncarriers (OR = 5.50, 95% CI = 1.18-35.20, P = 0.01). Our results replicate the proposed association between 5HT(2A)-C allele and suicidality in major depression. Moreover, no overall associations are detected when patients with major depression and controls are compared for 102T/C frequencies, suggesting that the increased risk for suicidality conferred by 5-HT(2A)-C allele is primarily associated with suicidal behavior and not with the diagnosis of major depression itself.

Dermatoglyphics and abnormal palmar flexion creases as markers of early prenatal stress in children with idiopathic intellectual disability

A number of studies have shown the importance of dermatoglyphics as markers of prenatal disturbance in developmental disorders of unknown origin. Genetic and non-genetic factors are involved in the aetiology of intellectual disability (ID), although the cause remains unknown in up to 50% of cases. The aim of the present study was to analyse dermatoglyphic traits and abnormal palmar flexion creases as markers of environmental prenatal stress in children with idiopathic ID (IID) using a case-control study design. Three dermatoglyphic variables, which have been reported as altered in other congenital disorders, were considered were studied in a sample of 62 children with IID (IQ < 70) and 75 healthy controls (IQ > 70): (1) fingerprint patterns; (2) total a-b ridge count (TABRC); and (3) abnormal palmar flexion creases (APFCs). More arches, the simplest fingerprint pattern, and more radial loops, an unusual pattern, were found in IID cases in comparison to controls (chi23 = 9.26; P = 0.02), with especially marked differences in boys (chi23 = 6.5; P = 0.0008). A significant increase of APFCs was also found in the affected children (chi24 = 28.52; P < 0.00; odds ration = 3.86, 95% confidence interval = 1.77-8.47). For TABRC, the differences between IID cases and controls failed to reach the conventional level of significance. These findings suggest that environmental factors acting early in development, or mechanisms involving an interaction of genotype and environment could be involved in the aetiology of some cases of ID.

Association study between novel promoter variants at the 5-HT2C receptor gene and human patients with bipolar affective disorder

Two recently described adjacent DNA polymorphisms [(GT)12-18 and (CT)4-5] in the 5'-regulatory region of 5-HT2C receptor gene were analysed in a sample of 88 bipolar patients and 162 controls, all of Spanish origin. Statistical analyses revealed no overall allele or genotype associations with the disease. A haplotype analyses between the (GT)12-18/(CT)4-5 motif and a Cys23Ser variant of the 5-HT2C gene (which had previously been genotyped in the same sample) showed similar distributions between cases and controls. Only a slight increase of s-Ser23 haplotype was found in the subgroup of bipolar women with family history of psychiatric illness (OR=1.24 [95%CI: 1.12-1.38]).

Genetic variation in the 5-HT5A receptor gene in patients with bipolar disorder and major depression

In the present study, genetic variation of the 5-HT5A receptor was analyzed in patients affected by affective disorders and healthy controls. The sample consisted of 181 patients with major depression, 88 patients with bipolar affective disorder (BP) and 157 unrelated controls (C), all of Spanish origin. Two polymorphisms (-19G/C and 12A/T) in the 5-HT5A receptor gene were analyzed by polymerase chain reaction amplification and subsequent enzyme digestion. No genotype, allele or haplotype differences were found when we compared patients and controls. When clinical variables were considered as possible tools for detecting genetic heterogeneity, no differences were found. Our results suggest that the polymorphisms analyzed in the 5-HT5A receptor gene do not play a major role in the pathogenesis of affective disorders.

Variability in the 5-HT(2A) receptor gene is associated with seasonal pattern in major depression

The 102-T/C polymorphism of the 5-HT(2A) receptor gene was analysed in 159 patients with major depression and 164 unrelated and healthy controls using a case-control design. Allele and genotype frequencies did not differ between cases and controls. No differences according to sex, age of onset, melancholia, suicidal behaviour or family history of psychiatric illness were found. However, genotype distributions significantly differed between patients with seasonal pattern in their episodes (MDS) and patients with no seasonal pattern (N-MDS) (chi(2) = 10.63; P = 0.004). A seasonal pattern was 7.57 times more frequent in 102C-allele carriers than in 102T homozygous (95.1% of patients MDS carried 102C-allele vs 72% of patients N-MDS (chi(2) = 9.45, df=1, P = 0.002; OR = 7.57 (95% CI: 1.65--48.08)). These results suggest that variation in the 5-HT2A receptor gene may play a role in the development of major depression with seasonal pattern and support the existence of a genetic and etiological heterogeneity underlying the diagnosis of major depression.