Working conditions, serotonin transporter gene polymorphism (5-HTTLPR) and anxiety disorders: a prospective cohort study

Hussenoeder F, Conrad I, Riedel-Heller S, Romero Starke K. Psychosocial Occupational Exposures and Mental Illness

BACKGROUND

The purpose of this study is to investigate the exposure-risk relationship between psychosocial occupational stress and mental illness.

METHODS

We conducted a systematic review with meta-analyses as an update of a systematic review published in 2014. The study protocol was registered in PROSPERO (CRD42020170032). Literature searches were carried out in the MEDLINE, PsycINFO, and Embase databases. All procedural steps were performed independently by two reviewers; discordances were solved by consensus. All of the included full texts were subject to a methodological appraisal. Certainty of evidence was determined with the GRADE procedure.

RESULTS

The pooled risk of depression was found to be approximately doubled in workers exposed to high job strain, which is defined as high work demands combined with low job control (effect estimate [EE] = 1.99, 95% CI [1.68; 2.35], heterogeneity [I2] = 24.7%, n = 8). In particular, high work demands are associated with incident depression (ES = 13.8 [1.19; 1.61], I2 = 69.0%, n = 9) and with incident anxiety disorder (ES = 1.79 [1.44; 2.23], I2 = 48.1%, n = 5). There were only a small number of methodologically adequate studies available on burnout, somatoform disorders, suicidal ideation, and suicide. Thus, no pooled risk estimates were calculated, although some individual studies showed a considerably increased risk.

CONCLUSION

Psychosocial occupational stress is clearly associated with depression and anxiety disorders.

A positron emission tomography study of the serotonergic system in relation to anxiety in depression

Symptoms of anxiety are highly comorbid with major depressive disorder (MDD) and are known to alter the course of the disease. To help elucidate the biological underpinnings of these prevalent disorders, we previously examined the relationship between components of anxiety (somatic, psychic and motoric) and serotonin 1A receptor (5-HT_1A) binding in MDD and found that higher psychic and lower somatic anxiety was associated with greater 5-HT_1A binding. In this work, we sought to examine the correlation between these anxiety symptom dimensions and 5-HTT binding. Positron emission tomography with [¹¹C]-3-amino-4-(3-dimethylamino-methylphenylsulfanyl)-benzonitrile ([¹¹C]DASB) and a metabolite-corrected arterial input function were used to estimate regional 5-HTT binding in 55 subjects with MDD and anxiety symptoms. Somatic anxiety was negatively correlated with 5-HTT binding in the thalamus (β=-.33, p=.025), amygdala (β=-.31, p=.007) and midbrain (β=-.72, p<.001). Psychic anxiety was positively correlated with 5-HTT binding in midbrain only (β=.46, p=.0025). To relate to our previous study, correlation between 5-HT_1A and 5-HTT binding was examined, and none was found. We also examined how much of the variance in anxiety symptom dimensions could be explained by both 5-HTT and 5-HT_1A binding. The developed model was able to explain 68% (p<.001), 38% (p=.012) and 32% (p=.038) of the total variance in somatic, psychic, and motoric anxiety, respectively. Results indicate the tight coupling between the serotonergic system and anxiety components, which may be confounded when using aggregate anxiety measures. Uncovering serotonin's role in anxiety and depression in this way may give way to a new generation of therapeutics and treatment strategies.

The serotonin transporter promoter polymorphism moderates the continuity of behavioral inhibition in early childhood

Persistently elevated behavioral inhibition (BI) in children is a marker of vulnerability to psychopathology. However, little research has considered the joint influences of caregiver and child factors that may moderate the continuity of BI in early childhood, particularly genetic variants that may serve as markers of biological plasticity, such as the serotonin transporter linked polymorphic region (5-HTTLPR). We explored this issue in 371 preschoolers and their caregivers, examining whether parent characteristics (i.e., overinvolvement or anxiety disorder) and child 5-HTTLPR influenced the continuity of BI between ages 3 and 5. Measures were observational ratings of child BI, observational and questionnaire measures of parenting, and parent interviews for anxiety disorder history, and children were genotyped for the 5-HTTLPR. Parent factors did not moderate the association between age 3 and age 5 BI; however, child BI at age 3 interacted with children's 5-HTTLPR variants to predict age 5 BI, such that children with at least one copy of the short allele exhibited less continuity of BI over time relative to children without this putative plasticity variant. Findings are consistent with previous work indicating the 5-HTTLPR short variant increases plasticity to contextual influences, thereby serving to decrease the continuity of BI in early childhood.