Exposure to Environmental and Psychological Stress and Neural Response to Own Infant among Mothers

Saturday, 21 de March de 2020

The postpartum period is an exciting yet stressful time of life. Exposure to chronic stress presents challenges in adaptation to motherhood (Social Interaction). The researchers in this study (1) previously reported that socioeconomic disadvantages were associated with the altered neural responses to infant cry and images among new mothers (Physiology & Behavior). However, what aspect of socioeconomic disadvantage is associated with maternal neural responses remains unclear. Thus, in the current study, they hypothesized that experiencing higher psychological distress and multiple environmental risks could be associated with the neural responses to infant cry and adaptation to motherhood.

Methods:

56 first-time new mothers (age M=25.9 years) participated in the study during 0-9 postpartum months (M=4.4 month). The participants had a diverse socioeconomic and racial/ethnic background (44% low-income; 31% Caucasian, 46% Hispanic).

Environmental risk included stressful life events and physical home environment stressors (housing quality, crowding, and noise). Psychological risk included perceived stress, depressive mood and anxious mood. First, each risk's score was coded as stress by assigning a 1 if the score is above mean plus one standard deviation, and 0 otherwise. Next, to calculate the cumulative index of the risk exposure, a sum score of the dichotomous variables of the ten risks was calculated. As parenting-related outcomes, a perception of parenting and parenting stress were assessed by.

The Infant Cry task was organized into two functional runs, in which blocks of cry stimuli and control sounds lasted 20 s. Each stimulus block was separated by an average 10-second rest period at which time only background scanner noise could be heard. Each run contained blocks of four sound stimuli-(A) own infant cry, (B) control infant cry, (D) own infant cry matched noise and (D) control infant cry matched noise.
Analysis of Functional Neuroimages software (AFNI) was used for preprocessing and statistical analysis.

At the group-level, AFNI's 3dLME was utilized to create a whole-brain linear mixed effects model with cumulative risk as a between-subjects quantitative variable, and sound (cry vs noise) and condition (own vs control) as within-subjects factors. Results were corrected for multiple comparisons within the whole brain using the cluster extent threshold of k ≥ 33 with a height threshold of p < 0.001, equivalent to a whole brain corrected false positive probability of P < 0.05, as calculated by 3dClustSim using the spatial autocorrelation function(acf) option.

Results:

Higher cumulative risk scores were associated with less positive perception of parenting, r(54)=-0.28, p< 0.05, and higher parenting stress, r(54)=0.44, p< 0.001. For neuroimaging data, the three-way interaction of cumulative risk X sound (cry vs noise) X condition (own infant vs control infant) revealed a significant cluster (Figure 1). Right cuneus (BA18; x, y, z=11, -73, 14, k=439) also included left cuneus, bilateral lingual gyrus, and right posterior cingulate (BA 17, 23, 30). Neural response to own infant cry vs. control infant cry was negatively associated with cumulative risk, r(54)=0.42, p<0.001. Thus, new mothers with high cumulative risk exposure exhibited greater neural responses to own baby cry sounds compared to control baby cry sounds.

·Figure 1. Right cuneus showing the positive associations between cumulative risk and the neural responses to own infant vs. control infant cry sounds

Conclusions:

The current study provides evidence for the role of environmental and psychological stress in neural responses to infant cry among new mothers. Higher exposure to environmental and psychological stress represent an unpredictable and chaotic environment. Thus, the elevated neural responses specifically to own infant's cry may reflect mothers' increased sensitivity to own infants' distress cues. However, the elevated sensitivity to the distress cues may come with a price as the mothers exposed to high risk also report more difficulties in adjusting to motherhood.

References

(1) Pilyoung Kim, Rebekah Ellis, Alexander Dufford, Andrew Erhart, Melissa Hansen, Aviva Olsavsky, Leah Grande. (2019). Exposure to Environmental and Psychological Stress and Neural Response to Own Infant among Mothers.

The content published here is the exclusive responsibility of the authors.

Autor: Sebastian Moguilner

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