This review critiques the article by Lehto et al. (2020) titled, “Childhood adoption and mental health in adulthood: The role of gene-environment correlations and interactions in the UK Biobank”. This article was published in the Biological Psychiatry journalon April 15, 2020, under the Society of Biological Psychiatry auspices.
Description of the Type of Research Used
Qualitative research was conducted in this study. The qualitative study collected data using a questionnaire with items that queried several aspects related to the relationship between adoption in childhood and mental health-related outcomes later in the life of the adoptees. The study sought to explore the genetic-environment correlations and interactions to explain the influence that early life adoption contributed to the poor mental health outcomes of the adoptees in adulthood. The sampled adoptees expressed their lived experiences through a self-reporting questionnaire designed to capture the phenotype, psychosocial factors, socioeconomic factors, health behavior, and polygenic risks.
Hypothesis and Summary of its Findings
The researchers hypothesized that the adoptees’ mental health characteristics are substantively inherited from their birth parents and that the exposure to childhood adversity emanated from genetic influences. The researchers also hypothesized that the genetically-influenced childhood adversities confounded the association between adoption during childhood and adverse mental health outcomes in adulthood. In other words, the study hypothesized that there existed gene-environment correlations and associations that predicated the adverse mental health outcomes of adoptees later in adulthood.
Adoptees demonstrated a higher propensity for adverse mental health outcomes compared to non-adoptees. This susceptibility was observed across most of the adverse mental health outcomes considered in the study. Similarly, the genetic risk for mental health disorders among parents predicted increased mental health risk in their children, and influenced entry into foster care significantly. Therefore, adverse childhood experiences are not solely responsible for the adoptees’ adverse mental health outcomes in adulthood. These findings demonstrated the existence of the genetic-environment correlation in mental disease development.
Critique of the Methods and Sample Used
The study employed a survey of a large population of adoptees, whose records were preserved in the United Kingdom Biobank (UKB). The survey approach used self-reporting questionnaires to reveal any adverse mental health outcomes that were encountered by childhood adoptees in adulthood. Self-reporting allows participants to respond to queries using their own lived experiences. However, questionnaires narrow the responses and allow respondents to select those that are closely related to or best describe their lived experiences. In this study, the participants responded to prompts investigating their lived experiences with adverse mental health outcomes as adults.
The sample of the adoptee population was obtained from a large database maintained by an ongoing long-term study assessing the contributions of genetic susceptibility and environmental factors to the development of ailments. In other words, the long-term study seeks to investigate the effects of nature and nurture on the development of diseases in the United Kingdom. This database already contains the genetic information of about half a million individuals, and therefore, it was not necessary to conduct genetic tests on the participants. The sample contained 243,797 participants who had conformed to the inclusion criteria set by the researchers out of 502,631 individuals contained in the database. Of these, 3151 individuals were adopted in childhood, thus forming the treatment groups, while the rest has not been adopted, and therefore comprise the control group for comparison. Therefore, since the participants were already captured in the large database, the need to rigorous randomized recruitment of participants was not necessary. This presented significant time and resource-saving advantages to the researchers.
Evaluation of Strengths and Weaknesses
This study has several notable strengths. Firstly, the study used a large sample of participants, making it more representative of the population. Secondly, it assessed a wide range of mental health outcomes, including depression, bipolar disorder, loneliness, neuroticism, and schizophrenia. The study went further to assess the socioeconomic and psychosocial outcomes to help qualify the mental health outcomes. Thirdly, the analysis delved into correlations and interactions between genetic predispositions and adverse mental health outcomes, which were scarce in previous studies. In this regard, the study contributed significantly to the nature and nurture debate about disease development.
However, the study also had significant limitations. Firstly, many of the participants were born in the 1950 and 1950s, and therefore they may have been unaware or unsure of their childhood adoption status, leading to data inaccuracy. Specifically, there may have been underreporting of the adoption status, as evidenced by the small number and proportion of adoptees compared to the non-adoptees in the database. Secondly, the extent of early childhood trauma was not measured related to the circumstances leading to entry into foster care, which is critical in explaining the genetic-environment interactions among adopted individuals. Thirdly, the mental health phenotype was assessed using few items in the questionnaire, thus delivering genetic information that was not comprehensive.
This study attended to a complex and elusive subject of determining the genetics-environment nexus in disease development. This study addressed a subject that challenges many researchers due to its complexity. Altogether, the findings of the study added to the existing knowledge related to the effects of nature and nurture on disease development among vulnerable individuals.
Lehto, K., Hägg, S., Lu, D., Karlsson, R., Pedersen, N. L., & Mosing, M. A. (2020). Childhood adoption and mental health in adulthood: The role of gene-environment correlations and interactions in the UK Biobank. Biological Psychiatry, 87(8), 708-716. https://doi.org/10.1016/j.biopsych.2019.10.016