Regulatory variant of the TPH2 gene and early life stress are associated with heightened attention to social signals of fear in infants

Abstract

Background: Cross-species evidence suggests that genetic and experiential factors act early in development to establish individual emotional traits, but little is known about the mechanisms that emerge during this period to mediate long-term outcomes. Here, we tested the hypothesis that known genetic and environmental risk conditions may heighten infants' natural tendency to attend to threat-alerting stimuli, resulting in a cognitive bias that may contribute to emotional vulnerability. Methods: Data from two samples of 5-7-month-old infants (N = 139) were used to examine whether established candidate variations in the serotonin-system genes, i.e., TPH2 SNP rs4570625 (-703 G/T) and HTR1A SNP rs6295 (-1019 G/C), and early rearing condition (maternal stress and depressive symptoms) are associated with alterations in infants' attention to facial expressions. Infants were tested with a paradigm that assesses the ability to disengage attention from a centrally presented stimulus (a nonface control stimulus or a neutral, happy, or fearful facial expression) toward the location of a new stimulus in the visual periphery (a geometric shape). Results: TPH2 -703 T-carrier genotype (i.e., TT homozygotes and heterozygotes), presence of maternal stress and depressive symptoms, and a combination of the T-carrier genotype and maternal depressive symptoms were associated with a relatively greater difficulty disengaging attention from fearful facial expressions. No associations were found with infants' temperamental traits. Conclusions: Alterations in infants' natural attentional bias toward fearful facial expressions may emerge prior to the manifestation of emotional and social behaviors and provide a sensitive marker of early emotional development.

Evidence for spared attention to faces in 7-month-old infants after prenatal exposure to antiepileptic drugs

“…Given that the test task performance was technically successful and very comparative with many previous studies [40,43], the lack of differences cannot be attributed to methodological issues in test administration. Furthermore, earlier work has shown that the eye-tracking-based method is sensitive enough to measure clinically subtle effects such as single nucleotide gene polymorphisms or preterm birth; both were shown to affect eye-tracking-based measures [62][63][64]. Thus, we would conclude that the present observations are valid and may tentatively speak for relative sparing of attention to faces in AED-exposed infants.…”

The impact of negative affect on attention patterns to threat across the first 2 years of life.

“…A strong line of studies has examined the emergence of differential attention to, and processing of, emotion stimuli, particularly as linked to threat processing (Peltola et al, 2015; Peltola et al, 2013; Peltola, Leppanen, Maki, et al, 2009; Peltola et al, 2008; Peltola, Leppanen, Vogel-Farley, et al, 2009). This literature has focused almost exclusively on normative changes over time (but see Forssman et al, 2014; Morales et al, in press; Peltola et al, 2015; Ravicz et al, 2015). In parallel, the anxiety literature has examined individual differences in threat processing as a putative causal mechanism for the emergence of social maladjustment and disorder (Dudeney et al, 2015; Pergamin-Hight, Naim, Bakermans-Kranenburg, van IJzendoorn, & Bar-Haim, 2015).…”

The development of attention to dynamic facial emotions

“…Many studies have examined the timing of the development of enhanced attention to threat-related negative emotions (e.g., fear, anger). For example, research by Peltola, Leppänen, and their colleagues shows that 7-month-olds, but not 5-month-olds, attend more to fearful faces than to happy or neutral faces in the presence of a competing stimulus (Forssman et al, 2014; Leppänen et al, 2010, 2011; Peltola, Forssman, Puura, van IJzendoorn, & Leppänen, 2015; Peltola, Hietanen, Forssman, & Leppänen, 2013; Peltola, Leppänen, Palokangas, & Hietanen, 2008; Peltola, Leppänen, Vogel-Farley, Hietanen, & Nelson, 2009). These studies led to the conclusion that the onset of enhanced attention to negative emotions occurs at around 7 months of age.…”