The genetic epidemiology of psychiatric disorders: a current perspective

Determining the stability of genome-wide factors in BMI between ages 40 to 69 years

Genome-wide association studies (GWAS) have successfully identified common variants associated with BMI. However, the stability of aggregate genetic variation influencing BMI from midlife and beyond is unknown. By analysing 165,717 men and 193,073 women from the UKBiobank, we performed BMI GWAS on six independent five-year age intervals between 40 and 72 years. We then applied genomic structural equation modeling to test competing hypotheses regarding the stability of genetic effects for BMI. LDSR genetic correlations between BMI assessed between ages 40 to 73 were all very high and ranged 0.89 to 1.00. Genomic structural equation modeling revealed that molecular genetic variance in BMI at each age interval could not be explained by the accumulation of any age-specific genetic influences or autoregressive processes. Instead, a common set of stable genetic influences appears to underpin genome-wide variation in BMI from middle to early old age in men and women alike.

Asian Americans and European Americans' stigma levels in response to biological and social explanations of depression

INTRODUCTION

Mental illness stigma is prevalent among Asian Americans, and it is a key barrier that prevents them from seeking psychological services. Limited studies have experimentally examined how Asian Americans respond to biological and social explanations of mental illness. Understanding how to educate and communicate about mental illness effectively is crucial in increasing service utilization among Asian Americans.

PURPOSE

To assess how genetic, neurobiological, and social explanations for the onset of depression affects Asian American and European American's mental illness stigma.

METHODS

231 Asian Americans and 206 European Americans read about an individual with major depression and were randomly assigned to be informed that the cause was either genetic, neurobiological, social, or unknown. Various stigma outcomes, including social distance, fear, and depression duration were assessed.

RESULTS

Consistent with prior research, Asian Americans had higher baseline levels of stigma compared to European Americans. Greater social essentialist beliefs predicted positive stigma outcomes for Asian Americans, such as a greater willingness to be near, help, and hire someone with depression, but genetic essentialist beliefs predicted negative stigma outcomes, such as fear. In addition, a social explanation for the etiology of depression led to lower stigma outcomes for Asian Americans; it decreased their fear of someone with depression and increased the perception that depression is treatable. For European Americans, both genetic and social essentialist beliefs predicted a greater perception of depression treatability.

CONCLUSION

Although genetics do play a role in the development of depression, emphasizing a social explanation for the origin of depression may help reduce stigma for Asian Americans.

The determinants of head and neck cancer: Unmasking the PI3K pathway mutations

Studies attempting to identify and understand the function of mutated genes and deregulated molecular pathways in cancer have been ongoing for many years. The PI3K-PTEN-mTOR signaling pathway is one of the most frequently deregulated pathways in cancer. PIK3CA mutations are found 11%-33% of head and neck cancer (HNC). The hotspot mutation sites for PIK3CA are E542K, E545K and H1047R/L. The PTEN somatic mutations are in 9-23% of HNC, and they frequently cluster in the phosphatase domain of PTEN protein. PTEN loss of heterozygosity (LOH) ranges from 41%-71% and loss of PTEN protein expression occurs in 31.2% of the HNC samples. PIK3CA and PTEN are key molecules in the PI3K-PTEN-mTOR signaling pathway. In this review, we provided a comprehensive overview of mutations in the PI3K-PTEN-mTOR molecular circuitry in HNC, including PI3K family members, TSC1/TSC2, PTEN, AKT, and mTORC1 and mTORC2 complexes. We discussed how these genetic alterations may affect protein structure and function. We also highlight the latest discoveries in protein kinase and tumor suppressor families, emphasizing how mutations in these families interfere with PI3K signaling. A better understanding of the mechanisms underlying cancer formation, progression and resistance to therapy will inform selection of novel genomic-based personalized therapies for head and neck cancer patients.

Adoption, family relations and psychotic symptoms among Palauan adolescents who are genetically at risk for developing schizophrenia

PURPOSE

This paper focuses on the role of adoption and family relations as moderators of genetic risk for psychotic disorders.

METHODS

Participants included 184 adolescents in the Republic of Palau identified to be at genetic risk for schizophrenia and other psychotic disorders. Palau is an island nation in Micronesia with a lifetime prevalence of 1.99% for schizophrenia and 2.67% for psychotic disorders more broadly defined. In Palauan culture, kinship adoption is a common cultural practice; 47 of the 184 participants had been adopted at an early age. The current study was designed to test the hypothesis that adoption would function as a protective factor among Palauan youth at genetic risk for the development of psychotic symptoms. Participants were evaluated for psychotic and other psychiatric symptoms using KSADS-PL. Concurrently, the Youth Self Report was used to assess the perceived quality of family relationships.

RESULTS

Results indicated that adopted adolescents were more likely to develop psychotic symptoms than non-adopted adolescents. However, perceived family relations moderated the association between adoption status and psychotic symptoms, such that adopted adolescents with poorer family relations reported disproportionately higher rates of psychotic symptoms. Family relations also moderated the association between level of genetic risk and psychotic symptoms, independently of adoption status.

CONCLUSION

Consistent with previous research, adolescents at high genetic risk who reported more positive family relations also reported fewer psychotic symptoms.

Does the influence of childhood adversity on psychopathology persist across the lifecourse? A 45-year prospective epidemiologic study

PURPOSE

Prospective evidence about whether the association of childhood adversity and psychopathology attenuates across the lifecourse and whether effects on mid-life psychopathology are mediated through adolescent and early adulthood psychopathology is limited.

METHODS

Data were from the 1958 British Birth Cohort, a 45-year study of 98% of births in 1 week in 1958 in England, Scotland, and Wales. Outcomes included International Statistical Classification of Diseases (ICD-10) diagnoses for affective and anxiety disorders at 45 years and psychopathology at 16 years and 23 years. Multiple multi-informant measures of childhood adversity were available at 7, 11, and 16 years, with additional retrospective measures of parental sexual and physical abuse at 45 years. Analyses were determined on the basis of N = 9377; 59% of the surviving sample.

RESULTS

After adjustment for socioeconomic covariates, childhood adversities were associated with adolescent, early adulthood, and mid-life psychopathology: most associations did not attenuate with age. Mid-life associations were significantly fully or partially mediated by early adulthood psychopathology: cumulative adversity, illness, sexual abuse, and physical abuse remained significantly associated with mid-life psychopathology.

CONCLUSIONS

The findings confirm the importance of preventing exposure to adversity and suggest that effects of adversity on mid-life psychopathology may operate through psychopathology in early adulthood. Future research is needed to examine other intermediary factors which may explain these associations.

Identification of new putative susceptibility genes for several psychiatric disorders by association analysis of regulatory and non-synonymous SNPs of 306 genes involved in neurotransmission and neurodevelopment

A fundamental difficulty in human genetics research is the identification of the spectrum of genetic variants that contribute to the susceptibility to common/complex disorders. We tested here the hypothesis that functional genetic variants may confer susceptibility to several related common disorders. We analyzed five main psychiatric diagnostic categories (substance-abuse, anxiety, eating, psychotic, and mood disorders) and two different control groups, representing a total of 3,214 samples, for 748 promoter and non-synonymous single nucleotide polymorphisms (SNPs) at 306 genes involved in neurotransmission and/or neurodevelopment. We identified strong associations to individual disorders, such as growth hormone releasing hormone (GHRH) with anxiety disorders, prolactin regulatory element (PREB) with eating disorders, ionotropic kainate glutamate receptor 5 (GRIK5) with bipolar disorder and several SNPs associated to several disorders, that may represent individual and related disease susceptibility factors. Remarkably, a functional SNP, rs945032, located in the promoter region of the bradykinin receptor B2 gene (BDKRB2) was associated to three disorders (panic disorder, substance abuse, and bipolar disorder), and two additional BDKRB2 SNPs to obsessive-compulsive disorder and major depression, providing evidence for common variants of susceptibility to several related psychiatric disorders. The association of BDKRB2 (odd ratios between 1.65 and 3.06) to several psychiatric disorders supports the view that a common genetic variant could confer susceptibility to clinically related phenotypes, and defines a new functional hint in the pathophysiology of psychiatric diseases.

Methodological innovations in the National Survey of American Life

This paper provides an overview of the conceptualization and methods used in the National Survey of American Life (NSAL). The objectives of the NSAL are to investigate the nature, severity, and impairment of mental disorders among national samples of the black and non-Hispanic white (n = 1,006) populations in the US, including African American (N = 3,570), and Afro-Caribbean (N = 1,623) immigrant and second and older generation, populations. National multi-stage probability methods were used in generating the samples and race/ethnic matching of interviewers and respondents were employed in the largely face-to-face interview, lasting on average 2 hours and 20 minutes. Two methodological approaches are described for addressing sampling coverage of individuals attached to, but not residing in, selected households at the time of the study. The paper also describes two approaches used to address concerns about the interpretations of standard symptom probe information in assessing serious mental disorders. This included a clinical reappraisal study designed to ascertain differences in symptom responding and ascertainment of cases (N = 677) in a subset of the same NSAL respondents. Finally, an abbreviated, novel method for estimating the prevalence of mental disorders in first-degree family members is described and the preliminary results from this new approach are reported.

The ethics of social risk reduction in the era of the biological brain

In keeping with our transdisciplinary orientation, in this article we try to do several things at once. We address research on preventing mental illness and its relation to existing conceptions of public health, a topic to which insufficient attention has been paid in the era of the biological brain, while using this case study to illustrate the limits of conventional approaches in bioethics. After identifying the crucial need for methodological self-consciousness in prevention research and policy, we explore the implications as they relate to (i) the values embedded in the choice of research designs and strategies, and (ii) contrasting intellectual starting points regarding the biological plausibility of preventing mental illness. We then draw attention to the need for more thoughtful analysis of the appropriate role and limits of economics in making choices about prevention of mental illness.

Understanding the roles of genome and envirome: methods in genetic epidemiology

BACKGROUND

In order to understand studies of psychiatric epidemiology focusing on the 'genome' and 'envirome', basic knowledge of the logic and methods is necessary.

AIMS

To provide a review of typical methods used in genetic epidemiology.

METHOD

Reviews of the research designs usually employed in quantitative and molecular genetic studies. Genotype-environment correlation and interaction are also discussed.

RESULTS

Quantitative genetic studies indicate that genetic influences are important for both psychiatric disorders and behavioural traits. Specific gene loci can be tested for associations with both psychiatric risk and behavioural traits by means of molecular genetic techniques. There has been little examination of genotype-environment correlation and interaction, although the few reports that have appeared suggest that these complex relationships are important.

CONCLUSIONS

Advances in quantitative and molecular genetics now permit more careful examination of genotype-environment interaction and correlation. Studies combining molecular genetic strategies with measurement of the environment are still at an early stage, however, and their results must be awaited.

Social phobia and avoidant personality disorder as related to parental history of social anxiety: a general population study

Using a validated and DSM-IV compatible questionnaire, the present study related family history of excessive social anxiety to social phobia and avoidant personality disorder (APD) in epidemiologically identified probands in the general population. Probands met diagnostic criteria for social phobia with or without APD and APD with or without social phobia. A two- to three-fold increased relative risk of social anxiety was observed for all diagnostic groups. Increasing severity in probands by varying diagnostic criteria did not affect the relative risk. Because familial aggregation of social anxiety was not modulated by Axis I or II diagnosis or diagnostic cut-off levels, data imply that social phobia and APD may represent a dimension of social anxiety rather than separate disorders. Thus, having an affected family member is associated with a two- to three-fold risk increase for both social phobia and APD.

Hospital-treated psychiatric disorders in adults with a single-parent and two-parent family background: a 28-year follow-up of the 1966 Northern Finland Birth Cohort

This study investigates the relationship between the family type (two-parent and 4 different single-parent types, mainly divorced) during childhood up to 14 years of age and adult hospital-treated psychiatric disorders in a sample from the unselected, general population Northern Finland 1966 Birth Cohort (N = 11,017). Up to the end of 1994, a total of 387 individuals (3.5%) had a hospital-treated psychiatric disorder, with 3.1% in two-parent families and 5.4% in single-parent families (p < .001). The single-parent family was not associated with the child's schizophrenia or other psychotic disorders. The adjusted odds ratios (OR) for personality disorders were highest among individuals without a father before the age of 14 years (OR 4.8), or at birth only (OR 4.0), or with a history of parental divorce (OR 2.8). Parental divorce was also associated with alcoholism (OR 3.7) and parental death with depressive disorders (OR 3.4). In conclusion, we found an elevated risk of hospital-treated nonpsychotic disorder among individuals from a single-parent family background. It is likely that a combination of the single-parent family and psychosocial and/or genetic risk may influence the development of these disorders.