Prediction of Adolescent Depression Using Evolutionary and Epigenetic Hypotheses

• In Event: Matches and Mismatches, Developmentally Informative and Sometimes Surprising!

Abstract

Introduction
The combination of two evolutionary hypotheses, that fetal conditions provide a forecast of likely postnatal environments (Predictive Adaptive Response) and that the female fetus is better adapted than the male fetus to maternal adversity (Trivers-Willard hypothesis) may be used to explain sex-dependent effects of mis-matched prenatal-postnatal environments. Additionally, animal studies have implicated that mediating epigenetic mechanisms at glucocorticoid genes may be moderated by tactile stimulation. We have previously demonstrated a three-way interaction between prenatal and postnatal anxiety and maternal stroking, in the prediction of child irritability at age 7, seen only in girls. This arose because lower maternal stroking was associated with higher irritability, only in the mis-matched, low-high and high-low maternal anxiety groups.
Hypotheses
The aim of this study was to examine whether such effects persisted into adolescence in the prediction of self-reported depression at age 13. Our specific hypotheses were as follows:
1) There will be a three-way interaction between maternal prenatal anxiety, postnatal anxiety and stroking in the prediction of depression at age 13.
2) This three-way interaction will only be evident in females, and not males.
3) The interaction will arise because low stroking will be associated with high adolescent depression only in the mis-matched low-high and high-low prenatal anxiety groups.
Study population
Data derives from a UK-based birth cohort, the Wirral Child Health and Development Study (WCHADS). This is a prospective, epidemiological longitudinal study starting in pregnancy with follow-up over several assessment time points during infancy, childhood, and adolescence.
Methods
Mothers provided self-report anxiety scores at 20 weeks of pregnancy, and at 9 weeks, 14 months and 3.5 years postpartum, and frequency of infant stroking at 9 weeks. Adolescents reported on their own symptoms of depression at age 13 years (complete data on N=535). Three-way interactions (prenatal anxiety X postnatal anxiety X stroking) using ANCOVA and accounting for potential confounders, were run for the whole sample and for males and females separately. Additionally, a four-category variable for maternal anxiety was created (low-low, low-high, high-low, high-high) and tested using ANCOVA in interaction with stroking and child gender to formally test for sex differences.
Results
There was a significant three-way interaction between prenatal anxiety, postnatal anxiety and stroking in the prediction of self-reported adolescent depression (p=0.010). When split by gender, the three-way interaction was significant for males (p=0.043) but not females (p=0.067). There was also a significant three-way interaction in the predication of adolescent depression when using the four-category maternal anxiety variable in interaction with stroking and child gender (p=0.037), which is supportive of a sex difference. The females with the highest depressive symptoms were those who were only exposed to high postnatal anxiety (i.e. low-high) and with low rates of stroking. This may be because this group were exposed to two disadvantageous postnatal insults – maternal depression and low stroking – unanticipated by their fetal conditions. For males exposed to any postnatal depression (i.e. low-high and high-high), increased maternal stroking was associated with increased depressive symptoms. However, in the absence of postnatal depression (i.e. low-low and high-low), increased stroking was associated with reduced depressive symptoms.

Authors

• Elizabeth Braithwaite, Manchester Metropolitan University
  Presenting Author

• Jonathan Hill, University of Reading

• Nicky Wright, Manchester Metropolitan University

• Andrew Pickles

• Helen Sharp, University of Liverpool