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Interaction of HPA axis genetics and early life stress shapes emotion recognition in healthy adults

BACKGROUND

Early life stress (ELS) affects facial emotion recognition (FER), as well as the underlying brain network. However, there is considerable inter-individual variability in these ELS-caused alterations. As the hypothalamic-pituitary-adrenal (HPA) axis is assumed to mediate neural and behavioural sequelae of ELS, the genetic disposition towards HPA axis reactivity might explain differential vulnerabilities.

METHODS

An additive genetic profile score (GPS) of HPA axis reactivity was built from 6 SNPs in 3 HPA axis-related genes (FKBP5, CRHR1, NR3C1). We studied two independent samples. As a proof of concept, GPS was tested as a predictor of cortisol increase to a psychosocial challenge (MIST) in a healthy community sample of n = 40. For the main study, a sample of n = 170 completed a video-based FER task and retrospectively reported ELS experiences in the Childhood Trauma Questionnaire (CTQ).

RESULTS

GPS positively predicted cortisol increase in the stress challenge over and above covariates. CTQ and genetic profile scores interacted to predict facial emotion recognition, such that ELS had a detrimental effect on emotion processing only in individuals with higher GPS. Post-hoc moderation analyses revealed that, while a less stress-responsive genetic profile was protective against ELS effects, individuals carrying a moderate to high GPS were affected by ELS in their ability to infer emotion from facial expressions.

DISCUSSION

These results suggest that a biologically informed genetic profile score can capture the genetic disposition to HPA axis reactivity and moderates the influence of early environmental factors on facial emotion recognition. Further research should investigate the neural mechanisms underlying this moderation. The GPS used here might prove a powerful tool for studying inter-individual differences in vulnerability to early life stress.

Variation in the corticotropin-releasing hormone receptor 1 (CRHR1) gene modulates age effects on working memory

Decline in working memory (WM) functions during aging has been associated with hippocampal dysfunction mediated by age-related changes to the corticotropin-releasing hormone (CRH) system. Recent reports suggest that GG-homozygous individuals of single nucleotide polymorphisms (rs110402 and rs242924) in the CRH receptor 1 (CRHR1) gene show increased stress vulnerability and decreased BOLD responses in WM relevant regions. However, until now, no study investigated the interaction effects of variation in the CRHR1 gene and age on individual differences in WM. Here, young, middle-aged and old subjects (N = 466) were genotyped for rs110402 and rs242924 within the CRHR1 gene and an n-back task was used to investigate the hypothesis that vulnerable genotypes (GG-homozygotes) would show impaired WM functions that might be magnified by increased CRH production with advancing age. Our results show an impact of genotype already in middle-age with significantly better performance in AT-carriers. Working memory performance in AT-carriers did not differ between young and middle-aged subjects, but was significantly impaired in old age. In GG-homozygotes, severe working memory dysfunction occurred already in middle age. Our data indicate that GG-homozygotes of CRHR1 rs110402 and rs242924 represent a genetically driven subtype of early WM impairments due to alterations in hippocampal CRHR1 activation. Early interventions that have proven effective in delaying cognitive decline appear to be particularly important for these subjects at risk for premature memory decline, who are in the prime of their personal and professional lives.

Interaction of early life stress and corticotropin-releasing hormone receptor gene: effects on working memory

BACKGROUND

Early life stress (ELS) experience is associated with persisting working memory (WM) deficits; changes to the corticotropin-releasing hormone (CRH) system; and structural, functional, and epigenetic changes in the hippocampus. Single nucleotide polymorphisms in the CRH receptor 1 (CRHR1) gene interact with ELS experience to predict depression as well as neuroendocrine and neuronal reactivity. Although these findings indicate that vulnerable genotypes might also show impaired WM performance after ELS experience, no previous study investigated whether there is an interaction effect of CRHR1 polymorphisms and ELS experience on WM performance.

METHODS

Subjects (N = 451) were genotyped for rs110402 and rs242924 within the CRHR1 gene. We used an n-back task to investigate the hypothesis that WM performance in healthy subjects may be subtly influenced by functional differences in CRHR1 and represents an early marker of increased vulnerability after exposure to ELS.

RESULTS

Exposure to ELS had a particularly strong impact on WM performance in subjects with the common homozygous GG GG genotype, whereas only severe exposure to ELS interfered with WM accuracy in AT carriers.

CONCLUSIONS

Our data indicate that specific CRHR1 polymorphisms moderate the effect of ELS experience on WM performance. Exposure to ELS in combination with a vulnerable genotype results in subtle memory deficits in adulthood, which might develop before psychopathological symptoms.