Association between the childhood rearing environment and general and specific psychopathology factors in middle adulthood: a Swedish National High-Risk Home-Reared versus Adopted-Away Sibling Comparison Study

Quasi-experimental and randomized controlled studies suggest that an enriched childhood rearing environment for at-risk individuals can reduce the risk for several psychiatric conditions. However, it remains uncertain if the reduced risk might be attributable to a general psychopathology factor common to all psychiatric conditions, versus specific psychopathology factors unique to only subsets of psychiatric conditions. In an at-risk sample, we estimated the association between an enriched childhood rearing environment and a latent bifactor model that captured both general and several specific psychopathology factors. The sample consisted of 881 full sibships where (a) the biological parents had (at least) one psychiatric diagnosis, suicide, or crime at any time in their lives, and (b) where (at least) one sibling was adopted away and raised by non-biological parents and (at least) one sibling raised by the biological parents. The exposure was whether a sibling was raised by biological versus adoptive parents. The outcome was a latent bifactor model based on nine conditions, including 7 in- or outpatient psychiatric diagnoses, suicide, and crimes. We recorded these outcomes from the birth of the siblings until the end of 2013, when the siblings were 34-64 years old. We used the marginal between-within model to estimate whether the adopted-away sibling(s) had lower scores on the latent factors. The latent bifactor model based on the nine conditions consisted of one general and three specific (externalizing, internalizing, and psychotic) psychopathology factors. The adopted-away siblings scored 0.27 (95% CI: -0.36, -0.18) standard deviations lower on the latent general psychopathology factor and 0.26 (95% CI: -0.38, -0.14) standard deviations lower on the latent specific externalizing factor, compared to their biological siblings who were raised by the biological parents. This result indicates that although genetics appears important for psychiatric comorbidity, the rearing environment also appears to play a systematic role in influencing the liability toward all mental health conditions among at-risk individuals. Improving the childhood rearing environment in high-risk families could potentially mitigate children's liability toward all psychiatric conditions.