Araceli Rosa

An experimental study of catechol-o-methyltransferase Val158Met moderation of delta-9-tetrahydrocannabinol-induced effects on psychosis and cognition.

Observational studies have suggested that psychometric psychosis liability and a functional polymorphism in the catechol-O-methyltransferase (COMT Val158Met) gene moderate the psychosis-inducing effect of cannabis. To replicate and extend this finding, a double-blind, placebo-controlled cross-over design was used in which patients with a psychotic disorder (n=30), relatives of patients with a psychotic disorder (n=12), and healthy controls (n=32) were exposed to Δ-9-tetrahydrocannabinol (Δ-9-THC, the principal component of cannabis) or placebo, followed by cognitive assessment and assessment of current psychotic experiences. Previous expression of psychometric psychosis liability was also assessed. Models of current psychotic experiences and cognition were examined with multilevel random regression analyses to assess (i) main effects of genotype and condition, (ii) interactions between condition and genotype, and (iii) three-way interactions between condition, genotype, and psychometric psychosis liability. Carriers of the Val allele were most sensitive to Δ-9-THC-induced psychotic experiences, but this was conditional on prior evidence of psychometric psychosis liability. Δ-9-THC impacted negatively on cognitive measures. Carriers of the Val allele were also more sensitive to Δ-9-THC-induced memory and attention impairments compared to carriers of the Met allele. Experimental effects of Δ-9-THC on cognition and psychosis are moderated by COMT Val158Met genotype, but the effects may in part be conditional on the additional presence of pre-existing psychosis liability. The association between cannabis and psychosis may represent higher order gene–environment and gene–gene interactions.

Clinical and neurocognitive predictors of functional outcome in bipolar euthymic patients: A long-term, follow-up study

OBJECTIVE To identify clinical and neurocognitive predictors of long-term functional outcome in patients with bipolar disorder METHODS A total of 32 subjects who met criteria for bipolar I or II disorder were recruited from the Barcelona Bipolar Disorder Program and were assessed clinically and neuropsychologically at baseline. After an average 4-year follow-up, they were interviewed with the Functioning Assessment Short Test (FAST) to assess functional outcome. Multivariate analyses were applied to identify clinical and neurocognitive predictors of functional outcome. RESULTS The main regression model for predictors of overall psychosocial functioning identified subclinical depressive symptoms (beta=0.516, t=3.51, p=0.002), and free delayed recall in a verbal memory task (beta=-0.314, t=-2.144, p=0.041), accounting for 36% of the variance. Specific predictors of occupational functioning were, again, subthreshold depression (beta=0.435, t=2.8, p=0.009) and a measure of executive function, digits backwards (beta=-0.347, t=-2.23, p=0.034). This model explained around 28% of the variance (corrected R(2)=0.28; F=6.38, gl=2, p=0.004). CONCLUSIONS Subdepressive symptomatology together with neurocognitive impairments related to verbal memory and executive functions are predictor variables of long-term functional outcome in bipolar disorder.

Weight gain in bipolar disorder : pharmacological treatment as a contributing factor

Objective:  The aim of this paper was to review the association of most commonly used psychopharmacological drugs with weight gain in bipolar disorder.

Neurocognitive, behavioural and neurodevelopmental correlates of schizotypy clusters in adolescents from the general population

Abstract Introduction : Studies on the neurocognitive correlates of schizotypy dimensions have found inconsistent results. This might stem from the fact that correlational methods, in contrast to cluster analysis, do not account for the possibility that a subject presents high scores on more than one dimension simultaneously. We aimed to establish clusters of normal adolescents based on schizotypy dimensions and compare them on neurocognitive, behavioural, and neurodevelopmental markers. Methods : Two hundred seventy normal adolescents from the general population (mean age 13.4, SD=0.72) attending obligatory education were evaluated. Results : A K-means iterative cluster analysis was performed with the Perceptual Aberration, Revised Social Anhedonia and Physical Anhedonia Scales. A forced four-cluster model yielded the following clusters: ‘negative schizotypy’, ‘high or mixed schizotypy’, ‘positive schizotypy’, and ‘normal scorers’. Comparisons with ANOVAs showed that ‘high schizotypes’ performed poorly on neurocognition (Wechsler Intelligence Scales for Children-Revised (WISC-R) and Verbal Fluency (FAS)) and obtained the highest teacher ratings (TRF) of behavioural problems. ‘Negative schizotypes’ had the worst WCST results and more dermatoglyphic abnormalities. Both clusters had more neurological soft signs than ‘normal scorers’ and ‘positive schizotypes’. Conclusions : Our results with community adolescents found the same cluster structure than the previous cluster analytic studies conducted in adult college subjects. Furthermore, we showed differences among them on neurocognitive and malneurodevelopment markers consistent with the adult literature on schizotypy.

Variability in the serotonin transporter gene and increased risk for major depression with melancholia

The serotonin transporter (SERT) gene is a particularly interesting candidate for genetic involvement in affective disorders owing to its role in both the regulation of serotonergic neurotransmission and the mechanism of action of many antidepressant drugs. In this study, variability in the SERT gene was analyzed for the first time in a sample of patients with major depression with melancholia (MDDM) in the context of a genetic association study. Two different polymorphisms of the SERT gene (17q11.1–17q12) were analyzed: a variable number of tandem repeats (VNTR) polymorphism in intron 2, and a deletion/insertion polymorphism (5-HTTLPR) in the promoter region of the gene, the short variant of which (allele 484) reduces the transcriptional efficiency of the SERT gene. Our sample consisted of 74 unrelated subjects who strictly met DSM-IV criteria for MDDM and 84 healthy controls, all of Spanish origin. The analysis of haplotype distribution for both polymorphisms showed significant differences between cases and controls (log-likelihood ratio χ2=11.15, df=4, P=0.025). Moreover, when the frequencies of the 484-STin2.10 haplotype were considered in comparison with any other haplotype combination, a significant increase in this haplotype was found in patients with MDDM [z=2.53 (95% CI, 1.21–5.34), P=0.007]. According to these results, variability in the SERT gene has a small effect on liability to MDDM. Our findings are compatible with an additive effect of both the 484 low-activity allele and a mutation elsewhere within the transporter gene or a susceptibility locus nearby in linkage disequilibrium with the VNTR marker.

Evidence that the COMTVal158Met polymorphism moderates sensitivity to stress in psychosis: An experience‐sampling study

Gene–environment interactions involving the catechol‐O‐methyltransferase Val158Met polymorphism (COMTVal158Met) have been implicated in the causation of psychosis. Evidence from general population studies suggests that Met/Met subjects are sensitive to stress, a trait associated with psychosis. We hypothesized that the Met allele would moderate the effects of stress on negative affect (NA) in controls, and on NA and psychosis in patients with a psychotic disorder. Thirty‐one patients with a psychotic disorder and comorbid cannabis misuse and 25 healthy cannabis users were studied with the experience sampling method (ESM), a structured diary technique assessing current context and emotional and psychotic experiences in daily life. A significant interaction between COMTVal158Met genotype and ESM stress in the model of NA was found for patients (interaction χ2 = 7.4, P = 0.02), but not for controls (interaction χ2 = 3.8, P = 0.15). In the model of ESM psychosis, a significant interaction between COMTVal158Met genotype and ESM stress was also apparent (interaction χ2 = 11.6, P < 0.01), with Met/Met patients showing the largest increase in psychotic experiences as well as NA in reaction to ESM stress. The findings suggest that the COMTVal158Met polymorphism moderates affective and psychotic responses to stress in patients with psychosis, providing evidence for gene–environment interaction mechanisms in the formation of psychotic symptoms.

COMT ValMet moderation of cannabis-induced psychosis: a momentary assessment study of 'switching on' hallucinations in the flow of daily life

Objective:  A functional polymorphism in the catechol‐o‐methyltransferase gene (COMT Val158Met) may moderate the psychosis‐inducing effects of cannabis. In order to extend this finding to dynamic effects in the flow of daily life, a momentary assessment study of psychotic symptoms in response to cannabis use was conducted.

The Val66Met polymorphism of the brain-derived neurotrophic factor gene is associated with risk for psychosis: Evidence from a family-based association study

Schizophrenia (SZ) is a prevalent and severe mental disorder. One of the most favored hypotheses for the etiology of SZ is the neurodevelopmental hypothesis. Brain‐derived neurotrophic factor (BDNF), a member of the neurotrophin growth factor family, promotes the development, regeneration, and survival of neurons and has been linked to the neuropathology of SZ. The present study tested, in a sample of 94 nuclear families, the hypothesis that the BDNF gene Val66Met polymorphism is associated to SZ and its psychopathologic phenotype using a multidimensional symptom approach. Furthermore, considering a reported reduction of BDNF in the frontal cortex of patients with SZ, we studied the relationship between this polymorphism and prefrontal function. The transmission disequilibrium test (TDT) showed a preferential transmission of allele Val from heterozygous parents to the affected offspring (P = 0.002), suggesting a possible role of this gene in the vulnerability to SZ spectrum disorders. The findings remained essentially unchanged when the analysis was restricted to the subgroup of patients with SZ (P = 0.009) and when a multidimensional approach to the diagnosis was used. Quantitative transmission disequilibrium test (QTDT) analyses did not demonstrate a significant association between the prefrontal tests assessed (Wisconsin Card Sorting Test and Trail Making Test) and the transmission of the BDNF alleles. Our finding suggests that the investigated BDNF polymorphism plays an important role in the phenotype of psychosis, but not in the performance of tests of prefrontal cognitive functions analyzed in these patients.

One‐year psychosocial functioning in patients in the early vs. late stage of bipolar disorder

Rosa AR, González‐Ortega I, González‐Pinto A, Echeburúa E, Comes M, Martínez‐Àran A, Ugarte A, Fernández M, Vieta E. One‐year psychosocial functioning in patients in the early vs. late stage of bipolar disorder.

Differential methylation of the X-chromosome is a possible source of discordance for bipolar disorder female monozygotic twins†

Monozygotic (MZ) twins may be subject to epigenetic modifications that could result in different patterns of gene expression. Several lines of evidence suggest that epigenetic factors may underlie mental disorders such as bipolar disorder (BD) and schizophrenia (SZ). One important epigenetic modification, of relevance to female MZ twins, is X‐chromosome inactivation. Some MZ female twin pairs are discordant for monogenic X linked disorders because of differential X inactivation. We postulated that similar mechanisms may also occur in disorders with more complex inheritance including BD and SZ. Examination of X‐chromosome inactivation patterns in DNA samples from blood and/or buccal swabs in a series of 63 female MZ twin pairs concordant or discordant for BD or SZ and healthy MZ controls suggests a potential contribution from X‐linked loci to discordance within twin pairs for BD but is inconclusive for SZ. Discordant female bipolar twins showed greater differences in the methylation of the maternal and paternal X alleles than concordant twin pairs and suggest that differential skewing of X‐chromosome inactivation may contribute to the discordance observed for bipolar disorder in female MZ twin pairs and the potential involvement of X‐linked loci in the disorder.