A sib-pair study of psychoticism, life events and depression

Cumulative impact of high job demands, low job control and high job insecurity on midlife depression and anxiety: a prospective cohort study of Australian employees

OBJECTIVE

There is a lack of evidence concerning the prospective effect of cumulative exposure to psychosocial job stressors over time on mental ill-health. This study aimed to assess whether cumulative exposure to poor quality jobs places employees at risk of future common mental disorder.

METHODS

Data were from the Personality and Total Health Through Life project (n=1279, age 40-46 at baseline). Data reported on the cumulative exposure to multiple indicators of poor psychosocial job quality over time (ie, a combination of low control, high demands and high insecurity) and future common mental disorder (ie, depressive and/or anxiety symptom scores above a validated threshold) 12 years later. Data were analysed using logistic regression models and controlled for potential confounders across the lifespan.

RESULTS

Cumulative exposure to poor-quality work (particularly more secure work) on multiple occasions elevated the risk of subsequent common mental disorder, independent of social, health, verbal intelligence and personality trait confounders (OR=1.30, 95% CI 1.06 to 1.59).

CONCLUSIONS

Our findings show that cumulative exposure to poor psychosocial job quality over time independently predicts future common mental disorder-supporting the need for workplace interventions to prevent repeated exposure of poor quality work.

An Overview of the Association between Schizotypy and Dopamine

Schizotypy refers to a constellation of personality traits that are believed to mirror the subclinical expression of schizophrenia in the general population. Evidence from pharmacological studies indicates that dopamine (DA) is involved in the etiology of schizophrenia. Based on the assumption of a continuum between schizophrenia and schizotypy, researchers have begun investigating the association between DA and schizotypy using a wide range of methods. In this article, we review published studies on this association from the following areas of work: (1) experimental investigations of the interactive effects of dopaminergic challenges and schizotypy on cognition, motor control, and behavior (2), dopaminergically supported cognitive functions (3), studies of associations between schizotypy and polymorphisms in genes involved in dopaminergic neurotransmission, and (4) molecular imaging studies of the association between schizotypy and markers of the DA system. Together, data from these lines of evidence suggest that DA is important to the expression and experience of schizotypy and associated behavioral biases. An important observation is that the experimental designs, methods, and manipulations used in this research are highly heterogeneous. Future studies are required to replicate individual observations, to enlighten the link between DA and different schizotypy dimensions (positive, negative, cognitive disorganization), and to guide the search for solid DA-sensitive behavioral markers. Such studies are important in order to clarify inconsistencies between studies. More work is also needed to identify differences between dopaminergic alterations in schizotypy compared to the dysfunctions observed in schizophrenia.

Estimating the heritability of reporting stressful life events captured by common genetic variants

BACKGROUND

Although usually thought of as external environmental stressors, a significant heritable component has been reported for measures of stressful life events (SLEs) in twin studies. Method We examined the variance in SLEs captured by common genetic variants from a genome-wide association study (GWAS) of 2578 individuals. Genome-wide complex trait analysis (GCTA) was used to estimate the phenotypic variance tagged by single nucleotide polymorphisms (SNPs). We also performed a GWAS on the number of SLEs, and looked at correlations between siblings.

RESULTS

A significant proportion of variance in SLEs was captured by SNPs (30%, p = 0.04). When events were divided into those considered to be dependent or independent, an equal amount of variance was explained for both. This 'heritability' was in part confounded by personality measures of neuroticism and psychoticism. A GWAS for the total number of SLEs revealed one SNP that reached genome-wide significance (p = 4 × 10-8), although this association was not replicated in separate samples. Using available sibling data for 744 individuals, we also found a significant positive correlation of R 2 = 0.08 in SLEs (p = 0.03).

CONCLUSIONS

These results provide independent validation from molecular data for the heritability of reporting environmental measures, and show that this heritability is in part due to both common variants and the confounding effect of personality.

Social support and trait personality are independently associated with resting cardiovascular function in women

OBJECTIVES

Social support is thought to positively influence appraisals of stressors and coping resources, thereby attenuating the harmful effects of stress. Notably, perceived available support (rather than actually received support) is believed to benefit well-being independent of the sense of obligation or threats to self-esteem that receiving support may entail. This study examined whether perceived support levels were associated with reduced cardiovascular levels, an important predictor of cardiovascular disease risk, independent of broad trait personality variables frequently reported to overlap with perceived support. In doing so, we sought to determine whether the effects of perceived support are independent of links between personality and social support.

DESIGN

A cross-sectional design was employed.

METHODS

Resting cardiovascular levels were measured using a Finometer in a sample of healthy women (N = 145). The Short-Form Social Support Questionnaire and the Revised Eysenck's Personality Questionnaire were used to assess support levels and personality. Regression was used to compare associations with psychometric indices of support (namely, perceived network size and perceived satisfaction with support) and personality (psychoticism, extraversion and neuroticism).

RESULTS

Support independently predicted systolic blood pressure (SBP; p = .03) and HR (p = .02) when personality was controlled for, while personality also predicted SBP (p = .01) and DBP (p = .02). Support effects were not mediated by personality.

CONCLUSIONS

The findings corroborate previous research indicating links between support and resting cardiovascular levels and additionally demonstrate these to be independent of associations between support and personality.

Genetic variation in the serotonin transporter modulates neural system-wide response to fearful faces

A distributed, serotonergically innervated neural system comprising extrastriate cortex, amygdala and ventral prefrontal cortex is critical for identification of socially relevant emotive stimuli. The extent to which a genetic variation of serotonin transporter gene 5-HTTLPR impacts functional connectivity between the amygdala and the other components of this neural system remains little examined. In our study, neural activity was measured using event-related functional magnetic resonance imaging in 29 right-handed, white Caucasian healthy subjects as they viewed mild or prototypical fearful and neutral facial expressions. 5-HTTLPR genotype was classified as homozygous for the short allele (S/S), homozygous for the long allele (L/L) or heterozygous (S/L). S/S showed greater activity than L/L within right fusiform gyrus (FG) to prototypically fearful faces. To these fearful faces, S/S more than other genotype subgroups showed significantly greater positive functional connectivity between right amygdala and FG and between right FG and right ventrolateral prefrontal cortex (VLPFC). There was a positive association between measure of psychoticism and degree of functional connectivity between right FG and right VLPFC in response to prototypically fearful faces. Our data are the first to show that genotypic variation in 5-HTTLPR modulates both the amplitude within and the functional connectivity between different components of the visual object-processing neural system to emotionally salient stimuli. These effects may underlie the vulnerability to mood and anxiety disorders potentially triggered by socially salient, emotional cues in individuals with the S allele of 5-HTTLPR.

Personality dimensions of people who suffer from visual stress

Personality dimensions of participants who suffer from visual stress were compared with those of normal participants using the Eysenck Personality Inventory. Extraversion-Introversion scores showed no significant differences between the participants who suffered visual stress and those who were classified as normal. By contrast, significant differences were found between the normal participants and those with visual stress in respect of Neuroticism-Stability. These differences accord with Eysenck's personality theory which states that those who score highly on the neuroticism scale do so because they have a neurological system with a low threshold such that their neurological system is easily activated by external stimuli. The findings also relate directly to the theory of visual stress proposed by Wilkins which postulates that visual stress results from an excess of neural activity. The data may indicate that the excess activity is likely to be localised at particular neurological regions or neural processes.