Genetic variation and shared biological susceptibility underlying comorbidity in neuropsychiatry

Association between tuberculosis and psychotic experiences: Mediating factors and implications for patient care in low- and middle-income countries

Background

Tuberculosis may play a role in the aetiology of psychosis. However, little is known about the association between tuberculosis and psychotic experiences (PEs) or the mediating factors of this association.

Methods

We analysed cross-sectional data from 48 low- and middle-income countries of the World Health Survey (WHS). Tuberculosis assessment was based on past 12-month symptoms of active tuberculosis. We assessed four types of past 12-month PEs with the Composite International Diagnostic Interview. We performed multivariable multinomial logistic regression and mediation analysis.

Results

We analysed data on 224 842 individuals aged ≥18 years (mean age = 38.3 years, standard deviation = 16.0; 50.7% women). Tuberculosis was associated with 1.84 (95% confidence interval (CI) = 1.41-2.40), 2.18 (95%CI = 1.58-3.03), and 3.79 (95%CI = 2.88-4.98) times higher odds for 1, 2, and ≥3 PEs, respectively. The mediation analysis showed that the association between tuberculosis and at least one PE is mainly explained by anxiety (31.5%), sleep/energy (27.8%), and pain/discomfort (23.5%).

Conclusions

Tuberculosis was associated with increased odds of PEs. Factors such as affect, sleep, and pain should be considered in tuberculosis patients to target those who might be particularly vulnerable to PEs, and consequently, to psychotic disorders and other adverse effects of PE.

Association of Polymorphism within the Putative miRNA Target Site in the 3'UTR Region of the DRD2 Gene with Neuroticism in Patients with Substance Use Disorder

The study aims at looking into associations between the polymorphism rs6276 that occurs in the putative miRNA target site in the 3'UTR region of the DRD2 gene in patients with substance use disorder (SUD) comorbid with a maniacal syndrome (SUD MANIA). In our study, we did not state any essential difference in DRD2 rs6276 genotype frequencies in the studied samples of SUD MANIA, SUD, and control subjects. A significant result was found for the SUD MANIA group vs. SUD vs. controls on the Neuroticism Scale of NEO FFI test, and DRD2 rs6276 (p = 0.0320) accounted for 1.7% of the variance. The G/G homozygous variants were linked with lower results on the neuroticism scale in the SUD MANIA group because G/G alleles may serve a protective role in the expression of neuroticism in patients with SUD MANIA. So far, there have been no data in the literature on the relationship between the miRSNP rs6276 region in the DRD2 gene and neuroticism (personal traits) in patients with a diagnosis of substance use disorder comorbid with the affective, maniacal type disturbances related to SUD. This is the first report on this topic.

Dissociative Symptoms and Disorders in Patients With Bipolar Disorders: A Scoping Review

Dissociative disorders are an important group of trauma-related disorders associated with significant disability. The co-occurrence of dissociative disorders (DD) and symptoms (DS) in bipolar disorder has been relatively understudied, but there is some evidence that this comorbidity may have significant mechanistic and clinical implications. This paper presents the results of a scoping review of the frequency and correlates of DS and DD in bipolar disorder. Based on the available evidence, DS/DD are more common in bipolar disorder than in healthy controls or in unipolar depression, are related to childhood trauma, and are associated with psychotic symptoms, suicide attempts, and a poorer response to treatment in patients with bipolar disorder. The implications of these findings, and possible mechanistic pathways underlying them, are discussed based on the current literature. Clinicians should be aware of the frequent occurrence of significant DS or DD when treating patients with bipolar disorder. A tentative future research agenda for this field, based on clinical, risk factor-related and neurobiological considerations, is outlined.

The Molecular Genetics of Dissociative Symptomatology: A Transdiagnostic Literature Review

Dissociative disorders are a common and frequently undiagnosed group of psychiatric disorders, characterized by disruptions in the normal integration of awareness, personality, emotion and behavior. The available evidence suggests that these disorders arise from an interaction between genetic vulnerability and stress, particularly traumatic stress, but the attention paid to the underlying genetic diatheses has been sparse. In this paper, the existing literature on the molecular genetics of dissociative disorders, as well as of clinically significant dissociative symptoms not reaching the threshold of a disorder, is reviewed comprehensively across clinical and non-clinical samples. Association studies suggest a link between dissociative symptoms and genes related to serotonergic, dopaminergic and peptidergic transmission, neural plasticity and cortisol receptor sensitivity, particularly following exposure to childhood trauma. Genome-wide association studies have identified loci of interest related to second messenger signaling and synaptic integration. Though these findings are inconsistent, they suggest biologically plausible mechanisms through which traumatic stress can lead to pathological dissociation. However, methodological concerns related to phenotype definition, study power, and correction for the confounding factors limit the value of these findings, and they require replication and extension in studies with better design.

The effect of ANKK1 Taq1A and DRD2 C957T polymorphisms on executive function: A systematic review and meta-analysis

Research in healthy adults suggests that C957T polymorphism of the dopamine D2 receptor encoding DRD2 and the Taq1A polymorphism of the neighbouring gene ankyrin repeat and kinase domain containing 1 (ANKK1) alter dopaminergic signalling and may influence prefrontally-mediated executive functions. A systematic review and meta-analysis was carried out on the evidence for the association of DRD2 C957T and ANKK1 Taq1A polymorphisms in performance on tasks relating to the three core domains of executive function: working memory, response inhibition and cognitive flexibility in healthy adults. CINAHL, MEDLINE, PsycARTICLES and PsychINFO databases were searched for predefined key search terms associated with the two polymorphisms and executive function. Studies were included if they investigated a healthy adult population with the mean age of 18-65 years, no psychiatric or neurological disorder and only the healthy adult arm were included in studies with any case-control design. Data from 17 independent studies were included in meta-analysis, separated by the Taq1A and C957T polymorphisms and by executive function tests: working memory (Taq1A, 6 samples, n = 1270; C957 T, 6 samples, n = 977), cognitive flexibility (C957 T, 3 samples, n = 620), and response inhibition (C957 T, 3 samples, n = 598). The meta-analyses did not establish significant associations between these gene polymorphisms of interest and any of the executive function domains. Theoretical implications and methodological considerations of these findings are discussed.

Polyunsaturated fatty acids and endocannabinoids in health and disease

Polyunsaturated fatty acids (PUFAs) are lipid derivatives of omega-3 (docosahexaenoic acid, DHA, and eicosapentaenoic acid, EPA) or of omega-6 (arachidonic acid, ARA) synthesized from membrane phospholipids and used as a precursor for endocannabinoids (ECs). They mediate significant effects in the fine-tune adjustment of body homeostasis. Phyto- and synthetic cannabinoids also rule the daily life of billions worldwide, as they are involved in obesity, depression and drug addiction. Consequently, there is growing interest to reveal novel active compounds in this field. Cloning of cannabinoid receptors in the 90s and the identification of the endogenous mediators arachidonylethanolamide (anandamide, AEA) and 2-arachidonyglycerol (2-AG), led to the characterization of the endocannabinoid system (ECS), together with their metabolizing enzymes and membrane transporters. Today, the ECS is known to be involved in diverse functions such as appetite control, food intake, energy balance, neuroprotection, neurodegenerative diseases, stroke, mood disorders, emesis, modulation of pain, inflammatory responses, as well as in cancer therapy. Western diet as well as restriction of micronutrients and fatty acids, such as DHA, could be related to altered production of pro-inflammatory mediators (e.g. eicosanoids) and ECs, contributing to the progression of cardiovascular diseases, diabetes, obesity, depression or impairing conditions, such as Alzheimer' s disease. Here we review how diets based in PUFAs might be linked to ECS and to the maintenance of central and peripheral metabolism, brain plasticity, memory and learning, blood flow, and genesis of neural cells.

Epigenetic Modulation of Mood Disorders

BACKGROUND

Mood disorders are expressed in many heterogeneous forms, varying from anxiety to severe major clinical depression. The disorders are expressed in individual variety through manifestations governed by co-morbidities, symptom frequency, severity, and duration, and the effects of genes on phenotypes. The underlying etiologies of mood disorders consist of complex interactive operations of genetic and environmental factors. The notion of endophenotypes, which encompasses the markers of several underlying liabilities to the disorders, may facilitate efforts to detect and define, through staging, the genetic risks inherent to the extreme complexity of disease state.

AIMS

This review evaluates the role of genetic biomarkers in assisting clinical diagnosis, identification of risk factors, and treatment of mood disorders.

METHODS

Through a systematic assessment of studies investigating the epigenetic basis for mood disorders, the present review examines the interaction of genes and environment underlying the pathophysiology of these disorders.

RESULTS

The majority of research findings suggest that the notion of endophenotypes, which encompasses the markers of several underlying liabilities to the disorders, may facilitate efforts to detect and define, through staging, the genetic risks inherent to the extreme complexity of the disease states. Several strategies under development and refinement show the propensity for derivation of essential elements in the etiopathogenesis of the disorders affecting drug-efficacy, drug metabolism, and drug adverse effects, e.g., with regard to selective serotonin reuptake inhibitors. These include: transporter gene expression and genes encoding receptor systems, hypothalamic-pituitary-adrenal axis factors, neurotrophic factors, and inflammatory factors affecting neuroimmune function. Nevertheless, procedural considerations of pharmacogenetics presume the parallel investment of policies and regulations to withstand eventual attempts at misuse, thereby ensuring patient integrity.

CONCLUSIONS

Identification of genetic biomarkers facilitates choice of treatment, prediction of response, and prognosis of outcome over a wide spectrum of symptoms associated with affective states, thereby optimizing clinical practice procedures. Epigenetic regulation of primary brain signaling, e.g., serotonin and hypothalamic-pituitary-adrenal function, and factors governing their metabolism are necessary considerations. The participation of neurotrophic factors remains indispensable for neurogenesis, survival, and functional maintenance of brain systems.

Understanding the Global Problem of Drug Addiction is a Challenge for IDARS Scientists

IDARS is an acronym for the International Drug Abuse Research Society. Apart from our scientific and educational purposes, we communicate information to the general and scientific community about substance abuse and addiction science and treatment potential. Members of IDARS are research scientists and clinicians from around the world, with scheduled meetings across the globe. IDARS is developing a vibrant and exciting international mechanism not only for scientific interactions in the domain of addiction between countries but also ultimately as a resource for informing public policy across nations. Nonetheless, a lot more research needs to be done to better understand the neurobiological basis of drug addiction - A challenge for IDARS scientists.

Psychotic-like experiences in major depression and anxiety disorders: a population-based survey in young adults

OBJECTIVE

Population-based surveys have confirmed that psychotic-like experiences are prevalent in the community. However, it is unclear if these experiences are associated with common mental disorders. The aim of this study was to examine the prevalence of psychotic-like experiences in those with affective and anxiety disorders.

METHODS

Subjects were drawn from the Mater-University of Queensland Study of Pregnancy. Delusion-like experiences were assessed with the Peters Delusional Inventory (PDI). The Composite International Diagnostic Interview (CIDI) was used to identify individuals with Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) lifetime diagnoses of major depression, anxiety disorder, substance use/dependence, and psychotic disorders. The influence of affective and anxiety disorders on PDI and CIDI psychosis-related items' scores were assessed with logistic regression, with adjustments for age, sex, and the presence of the other comorbid psychiatric diagnoses.

RESULTS

Having either a lifetime diagnosis of major depressive disorder or an anxiety disorder was associated with significantly higher PDI total scores (highest vs lowest quartile adjusted odds ratios [ORs] and 95% confidence intervals [CIs] = 4.43, 3.09-6.36; 3.08, 2.26-4.20, respectively). The odds of endorsing any CIDI hallucination or delusion item was increased in those with a major depressive or anxiety disorder. The presence of current anxiety disorder symptoms was significantly associated with PDI score (OR = 5.81, 95% CI = 3.68-9.16).

CONCLUSION

While psychotic-like experiences are usually associated with psychotic disorders, individuals with depression and anxiety are also more likely to report these symptoms compared with well individuals. Psychotic-like experiences are associated with a range of common mental disorders.

The tryptophan hydroxylase 1 (TPH1) gene, schizophrenia susceptibility, and suicidal behavior: a multi-centre case-control study and meta-analysis

Serotonin (5-hydroxytryptamin; 5-HT) alternations has since long been suspected in the pathophysiology of schizophrenia. Tryptophan hydroxylase (tryptophan 5-monooxygenase; TPH) is the rate-limiting enzyme in the biosynthesis of 5-HT, and sequence variation in intron 6 of the TPH1 gene has been associated with schizophrenia. The minor allele (A) of this polymorphism (A218C) is also more frequent in patients who have attempted suicide and individuals who died by suicide, than in healthy control individuals. In an attempt to replicate previous findings, five single nucleotide polymorphisms (SNPs) were genotyped in 837 Scandinavian schizophrenia patients and 1,473 controls. Three SNPs spanning intron 6 and 7, including the A218C and A779C polymorphisms, were associated with schizophrenia susceptibility (P = 0.019). However there were no differences in allele frequencies of these loci between affected individuals having attempted suicide at least once and patients with no history of suicide attempts (P = 0.84). A systematic literature review and meta-analysis support the A218C polymorphism as a susceptibility locus for schizophrenia (odds ratio 1.17, 95% confidence interval 1.07-1.29). Association studies on suicide attempts are however conflicting (heterogeneity index I(2) = 0.54) and do not support the A218C/A779C polymorphisms being a susceptibility locus for suicidal behavior among individuals diagnosed with a psychiatric disorder (OR = 0.96 [0.80-1.16]). We conclude that the TPH1 A218/A779 locus increases the susceptibility of schizophrenia in Caucasian and Asian populations. In addition, the data at hand suggest that the locus contributes to the liability of psychiatric disorders characterized by elevated suicidal rates, rather than affecting suicidal behavior of individuals suffering from a psychiatric disorder.

Cannabinoid receptors in brain: pharmacogenetics, neuropharmacology, neurotoxicology, and potential therapeutic applications

Much progress has been achieved in cannabinoid research. A major breakthrough in marijuana-cannabinoid research has been the discovery of a previously unknown but elaborate endogenous endocannabinoid system (ECS), complete with endocannabinoids and enzymes for their biosynthesis and degradation with genes encoding two distinct cannabinoid (CB1 and CB2) receptors (CBRs) that are activated by endocannabinoids, cannabinoids, and marijuana use. Physical and genetic localization of the CBR genes CNR1 and CNR2 have been mapped to chromosome 6 and 1, respectively. A number of variations in CBR genes have been associated with human disorders including osteoporosis, attention deficit hyperactivity disorder (ADHD), posttraumatic stress disorder (PTSD), drug dependency, obesity, and depression. Other family of lipid receptors including vanilloid (VR1) and lysophosphatidic acid (LPA) receptors appear to be related to the CBRs at the phylogenetic level. The ubiquitous abundance and differential distribution of the ECS in the human body and brain along with the coupling to many signal transduction pathways may explain the effects in most biological system and the myriad behavioral effects associated with smoking marijuana. The neuropharmacological and neuroprotective features of phytocannabinoids and endocannabinoid associated neurogenesis have revealed roles for the use of cannabinoids in neurodegenerative pathologies with less neurotoxicity. The remarkable progress in understanding the biological actions of marijuana and cannabinoids have provided much richer results than previously appreciated cannabinoid genomics and raised a number of critical issues on the molecular mechanisms of cannabinoid induced behavioral and biochemical alterations. These advances will allow specific therapeutic targeting of the different components of the ECS in health and disease. This review focuses on these recent advances in cannabinoid genomics and the surprising new fundamental roles that the ECS plays in the retrograde signaling associated with cannabinoid inhibition of neurotransmitter release to the genetic basis of the effects of marijuana use and pharmacotherpeutic applications and limitations. Much evidence is provided for the complex CNR1 and CNR2 gene structures and their associated regulatory elements. Thus, understanding the ECS in the human body and brain will contribute to elucidating this natural regulatory mechanism in health and disease.