The 5-HTTLPR genotype, early life adversity and cortisol responsivity to psychosocial stress in women

The role of maternal touch in the association between SLC6A4 methylation and stress response in very preterm infants

Very preterm (VPT) infants requiring hospitalization in the Neonatal Intensive Care Unit (NICU) are exposed to several stressful procedural experiences. One consequence of NICU-related stress is a birth-to-discharge increased serotonin transporter gene (SLC6A4) methylation that has been associated with poorer stress regulation at 3 months of age. Maternal touch is thought to support infants' stress response, but its role in moderating the effects of SLC6A4 methylation changes is unknown. The aim of this study was to assess the role of maternal touch in moderating the association between increased SLC6A4 methylation and stress response in 3-month-old VPT infants. Twenty-nine dyads were enrolled and at 3 months (age corrected for prematurity), participated in the Face-to-Face Still-Face paradigm to measure infants' stress response (i.e., negative emotionality) and the amount of maternal touch (i.e., dynamic and static). Results showed that low level of maternal touch is associated with high level of negative emotionality during social stress. Furthermore, during NICU stay SLC6A4 methylation in VPT exposed to low level of maternal touch at 3 months was associated with increased negative emotionality. Thus, low levels of maternal static touch can intensify the negative effects of SLC6A4 epigenetic changes on stress response in 3-month-old VPT infants.

Threat-Avoidance Tendencies Moderate the Link Between Serotonin Transporter Genetic Variation and Reactive Aggression

The short (S) allele of the serotonin transporter-linked promoter region (5-HTTLPR) polymorphism has been linked to reactive aggression in men, but this association is less consistent in females. Reactive aggression has been particularly described as a result of fear-driven defense to threat, but how this interaction between defensive behavior and aggression is expressed in S-allele carriers remains unknown. In order to explore this interplay between 5-HTTLPR genotype, defensive behavior and reactive aggression, we combined genotyping with objective measures of action tendencies toward angry faces in an approach-avoidance task (AAT) and reactive aggression in the Taylor aggression paradigm (TAP) in healthy females, N = 95. This study shows that female S-allele carriers in general display increased implicit reactive aggression (administering aversive white noise) toward opponents. Furthermore, we found that threat-avoidance tendencies moderate the association between 5-HTTLPR genotype and aggression displayed on the TAP. Together, these findings indicate a positive correlation between avoidance of angry faces in the AAT and reactive aggression in the TAP exclusively present in S-allele carriers.

Biomarkers of suicidal behaviors: A comprehensive critical review

Suicide is a relevant worldwide public health problem. Many studies have shown that different demographic and clinical factors are potentially associated with suicidal behavior. Other studies have reported data about the role of biomarkers in the onset of suicidal behaviors. Specifically, researchers have found that suicidal risk may be increased by abnormalities in serotonergic system, hypothalamic-pituitary-adrenal axis, lipid metabolism, immune system and neuronal plasticity. The identification of specific biological parameters associated with self-harm may be helpful to implement prevention strategies and also to detect new therapeutic strategies. In this review, we summarize and analyze the results of main studies about neurobiological mechanisms related to suicidal behavior, also exploring the possible interconnection between the different biological systems.

Influence of early adversity on cortisol reactivity, SLC6A4 methylation and externalizing behavior in children of alcoholics

BACKGROUND

Children of parents with alcoholism face considerable stress, and often have externalizing behaviors. Early adversity is known to affect DNA methylation and the functioning of the HPA axis. We investigated the association of early adversity with cortisol reactivity, 5HTTLPR genotype, site specific DNA methylation in the SLC6A4 gene and externalizing behavior in children of alcoholics (COA), and a matched sample of control children.

METHODS

We examined children of alcoholics (N = 50) and age matched control children (N = 50) for exposure to early adversity (both prenatal and postnatal), assessed their salivary cortisol reactivity and evaluated their levels of emotional and behavioral difficulty in terms of externalizing and internalizing behavior. Site-specific DNA methylation at a previously characterized SLC6A4 region was determined in salivary DNA using pyrosequencing. The 5HTTLPR region of the SLC6A4 gene was also genotyped.

RESULTS

COA had significantly higher experience of early adversity than control children. Cortisol reactivity was reduced in COA, and negatively correlated with early adversity. Both early adversity and cortisol reactivity correlated with externalizing behavior. SLC6A4 methylation was higher in COA, and correlated with early adversity. SLC6A4 genotype did not show association with any of the variables.

CONCLUSION

Our study provides further evidence that early adversity is associated with blunted cortisol reactivity, increased site-specific CpG DNA methylation at the SLC6A4 gene, and high externalizing behavior.