Neurodevelopmental disruptions caused by obstetric complications play a role in the etiology of several phenotypes associated with neuropsychiatric diseases and cognitive dysfunctions. Importantly, it has been noticed that epigenetic processes occurring early in life may mediate these associations. Here, DNA methylation signatures at IGF2 (insulin-like growth factor 2) and IGF2BP1-3 (IGF2-binding proteins 1-3) were examined in a sample consisting of 34 adult monozygotic (MZ) twins informative for obstetric complications and cognitive performance. Multivariate linear regression analysis of twin data was implemented to test for associations between methylation levels and both birth weight (BW) and adult working memory (WM) performance. Familial and unique environmental factors underlying these potential relationships were evaluated. A link was detected between DNA methylation levels of two CpG sites in the IGF2BP1 gene and both BW and adult WM performance. The BW-IGF2BP1 methylation association seemed due to non-shared environmental factors influencing BW, whereas the WM-IGF2BP1 methylation relationship seemed mediated by both genes and environment. Our data is in agreement with previous evidence indicating that DNA methylation status may be related to prenatal stress and later neurocognitive phenotypes. While former reports independently detected associations between DNA methylation and either BW or WM, current results suggest that these relationships are not confounded by each other.
The functional variant Val(158)Met in the coding sequence of COMT gene is involved in the modulation of dopamine availability in the prefrontal cortex in both clinical and general population samples. It has been suggested that the interplay between this genotype and early environmental factors could be used to predict the observed variation in cognitive flexibility. However, other genetic variants and environmental factors may confound the association and produce the inconsistent results commonly found in the literature. In the present study we aimed at testing putative interaction mechanisms between childhood maltreatment and COMT genotypic variability that might explain a proportion of the observed variability of cognitive flexibility in the population. Our design was based on a sample of adult monozygotic twins, which allowed us to test these effects free from potential genetic and shared-environmental confounding factors. Results showed that unique environmental effects of childhood maltreatment significantly impacted cognitive performance among Met/Met subjects. Interestingly, the direction of the association indicated that exposure to early stressful experiences was associated with enhanced cognitive flexibility in this genotype group. These results suggest that COMT may operate as a plasticity gene that provides differential cognitive capacity to respond to environmental stressors.
The influence of genetic and/or environmental factors on the volumetric brain changes observed in subjects affected by anxiety and depression disorders remains unclear. The current study aimed to investigate whether genetic and environmental liabilities make different contributions to abnormalities in gray matter volume (GMV) in anxiety and depression using a concordant and discordant MZ twin pairs design.
Early-onset schizophrenia is considered to be neurobiologically similar to adult-onset forms, although it represents a more severe expression of the disorder. In the present study, we explored putative larger familial vulnerability of intellectual impairments in early-onset schizophrenia spectrum disorders (EOS) when compared to adult-onset (AOS) families.
The XVIIIth World Congress of Psychiatric Genetics, sponsored by The International Society of Psychiatric Genetics took place in Athens, Greece on October 3-7, 2010. Approximately 950 participants gathered to discuss the latest findings in this rapidly advancing field. The following report was written by junior travel awardees, as well as others who were volunteers from student meeting attendees. Each was assigned sessions as rapporteurs. This report represents some of the areas covered in oral presentation during the conference, and reports on some of the notable major new findings described at this 2010 World Congress of Psychiatric Genetics.
Dysbindin-1 is a relatively ubiquitous protein in the brain which is involved in the modulation of synaptic homeostasis. The dysbindin-1 gene (DTNBP1) has been associated with schizophrenia and bipolar disorder diagnoses. However, its contribution to the severity of the clinical and neurocognitive expression of these disorders remains controversial. We aimed to explore the association between DTNBP1 and the phenotypes which are more directly linked with the underlying biology, such as age at onset and neurocognitive impairment. The present family sample comprised 894 Caucasian individuals: 268 patients affected by functional psychosis [58% with illness onset before 18 years, mean age at onset (SD): 14.71 (2.10)], 483 parents and 143 siblings. Ten DTNBP1 single nucleotide polymorphisms were genotyped in all individuals and their transmission disequilibrium was tested in relation to: (i) the risk for psychosis; (ii) patients age at onset; and (iii) familial neurocognitive performance (including IQ estimation and executive functioning). In early-onset families a 5-marker haplotype encompassing exons 2-4 and the surrounding introns was significantly over-transmitted to cases, while in adult-onset families two haplotypes corresponding to the region between introns 4 and 7 were over-transmitted to cases. Estimated IQ was associated with the rs760666 marker in the whole sample, whereas a significant association between executive functioning and the rs2619522 marker appeared in early-onset families. Our findings confirm the role of the dysbindin-1 gene in the risk for functional psychosis and show a differential haplotypic risk pattern in families with early as opposed to adult onset in the affected offspring.
Abnormalities in white matter (WM) volumes and integrity in schizophrenia, together with post-mortem studies showing reduced expression of oligodendrocyte/myelination genes and apoptotic processes taking place in oligodendrocytes, suggest the interest of major regulators of apoptosis as candidate genes for some features related to myelin integrity in schizophrenia. Protein p53, encoded by TP53 gene, has a central role in the control of apoptosis and is involved in oligodendrocyte development. TP53 gene polymorphisms may account for variability in WM features, metabolic activity and biochemical markers of neuronal integrity and membrane turnover. Pro72Arg and Ins16bp polymorphisms at TP53 gene were analyzed in 20 DSM-IV schizophrenia patients. T1/T2-weighted sequences of these patients were acquired using a 1.5T Philips Gyroscan system. Scans were transformed into Talairach space and segmented into gray matter (GM), WM and cerebrospinal fluid (CSF) using Statistical Parametric Mapping under a ROI approach. Likewise dorsolateral prefrontal cortex (DLPFC) metabolic activity was measured using a procedure based on MRI/PET image fusion. In 13 of these patients proton magnetic resonance spectroscopy was used to examine N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) levels in dorsolateral-medial prefrontal cortex (DLMPFC). MRI data were adjusted for age and brain volume using regression parameters from a healthy control group (n=45). Patients Pro/Arg heterozygous (Pro72Arg polymorphism) showed a generalized deficit in whole-brain WM that was especially prominent in frontal lobe and a lower metabolic activity in the DLPFC as compared to Pro/Pro homozygous. Pro/Arg subjects also showed decreased NAA/Cho and increased Cho/Cr ratios in right DLMPFC. TP53 genetic variability influences WM volumes in frontal lobes and it seems to modulate the metabolic activity in this region. Our results suggest that TP53 might influence aspects of myelin and white matter integrity which may account for some of the frontal dysfunction features commonly described in these patients.
Early-onset bipolar disorder is an impairing condition that is strongly associated with genetic inheritance. Neurocognitive deficits are core traits of this disorder which seem to be present in both young and adult forms. Deficits in verbal memory and attention are persistent within euthymic phases in bipolar adults, adolescents, and children. In younger samples, including type I or II and not otherwise specified patients, executive functions are not widely impaired and the existence of visual-spatial deficits remains unclear. The main aim of this study was to compare the neurocognitive performance in young stabilized type I or II bipolar patients and healthy controls. Fifteen medicated adolescents with bipolar disorder and 15 healthy adolescents, matched in age and gender, were compared on visual-spatial skills (reasoning, memory, visual-motor accuracy) and executive functioning (attention and working memory, set-shifting, inhibition) using t-tests and MANCOVA. Correcting for verbal competence, MANCOVA showed that patients performed significantly worse than controls in letters and numbers sequencing (P = 0.003), copy (P < 0.001) and immediate recall (P = 0.007) of the Rey Complex Figure Test, interference of the Stroop Color-Word Test (P = 0.007) and non-perseverative errors on the Wisconsin Card Sorting Test (P = 0.038). Impaired cognitive performance was found in young bipolar patients in working memory, visual-motor skills, and inhibitory control.
Childhood maltreatment and low socioeconomic status (SES) are considered stressful environmental events with lasting detrimental effects on adult mental health and associated cognitive performance, such as memory. However, the association between childhood maltreatment and low SES remains unclear, probably due to design limitations and putative confounding factors. Particular concerns have been raised on genetic influences, as genetic background may modulate the effects of environmental stressors. The aim of the present study was to examine the effect of childhood maltreatment on adult memory in low- and high-SES subjects, free of confounding due to other environmental and genetic influences. A monozygotic twin design based on 188 healthy adult subjects (94 twin pairs) from the general population was conducted. This design based on genetically identical individuals allowed disentangling the unique environmental effects of childhood maltreatment on memory, which was explored in low and high SES. Results showed that the unique environmental effects of childhood maltreatment were only evident in the high-SES group (? = -0.22; SE = 0.08; p < 0.01; 95 % CI = -0.375 to -0.066). By contrast, no evidence for this effect could be detected in the more stressful low-SES group. These results suggest that enriched environments may provide a more stable context where early stressful experiences can influence cognitive processes. This study provides preliminary support for the inclusion of environmental enrichment in studies addressing the impact of childhood maltreatment on adult cognition and psychiatric disorders.
Genetic studies have found that the interleukin-1? gene (IL1B, 2q13) influences the risk for schizophrenia, but the underlying biological mechanisms of the association are still unclear. Investigation of the effects of genetic variability in this gene on brain function could provide more information about its role in the disorder.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.