Liability for schizophrenia in mothers and children was positively associated with exposure to trauma during childhood and adolescence, according to a publication in Psychological Medicine. Prior research has shown an association between childhood trauma and psychotic illness, suggesting an interaction between genes and environment that can increase an individual’s risk.
In this study, the researchers examined the association between schizophrenia polygenic scores (PGS) and childhood trauma. They used data from 2 prospective, population-based pregnancy cohort studies. In both studies, PGS were determined using genetic data from participants that were analyzed by summary statistics published by the Psychiatric Genomics Consortium.
The Avon Longitudinal Study of Parents and Children (ALSPAC) aimed to recruit pregnant women who were expected to give birth between April 1991 and December 1992. Trauma exposure was collected from 0 to 17 years with intervals from 0-4.9 years, 5-10.9 years, and 11-17 years. Data was also collected retrospectively at 22 years. Trauma exposure was assessed using questionnaires completed by parents and children and then divided into the categories of bullying, domestic violence, sexual abuse, emotional neglect, emotional cruelty, and physical cruelty. The Norwegian Mother, Father and Child Cohort Study (MoBa) recruited pregnant participants across Norway from 1999 to 2008. Childhood trauma was measured at age 8 using maternal response to questionnaires.
Schizophrenia liability of both mother and child were significantly correlated with childhood trauma in both cohort studies. In the ALSPAC study, from ages 0-17 years, schizophrenia PGS of both mothers (n=7380; odds ratio [OR], 1.13; 95% CI, 1.06-1.20, P <.05) and children (n=7426; OR, 1.14; 95% CI, 1.08-1.20, P <.05) were associated with increased exposure to childhood trauma across all age groups. Although not significant, there was a trend for an association between schizophrenia PGS of fathers (n=1215; OR, 1.04; 95% CI, 0.92-1.17, P <.05) and childhood trauma. Most subtypes of childhood trauma, except for bullying in the case of the PGS of mothers and children and emotional neglect in child PGS, were significantly correlated with schizophrenia liability.
In the MoBa study, at age 8, schizophrenia PGS of both mothers (n=7009; OR, 1.10; 95% CI, 1.04-1.16, P <.05) and children (n=7244; OR, 1.08; 95% CI, 1.02-1.14, P <.05) were associated with increased exposure to all categories of childhood trauma. Schizophrenia PGS of fathers (n=7153; OR, 1.06; 95% CI, 1.00-1.11, P =.052) showed a nonsignificant trend with childhood trauma.
Limitations to the study included a substantial amount of missing data, participant attrition, and reliance on parental response to questionnaires alone in the MoBa study, all of which could contribute to selection bias.
The researchers stated that childhood trauma, with the exception of bullying, generally occurred at home, denoting a “traumagenic environment.” They concluded, “Prevention measures should focus on parents and supporting a healthy home life earlier on in childhood and targeting the children themselves as they approach adolescence.”
Sallis HM, Croft J, Havdahl A, et al. Genetic liability to schizophrenia is associated with exposure to traumatic events in childhood [published online ahead of print, 2020 Apr 1]. Psychol Med. 2020;1–8.