Responsibilities such as Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing were fulfilled by the team.

The study was conducted by the Department of Pediatrics and Adolescent Medicine at the University of Turku and Turku University Hospital in Turku, Finland.

• Anna-Riitta Heikkilä,
• Marko Elovainio,
• Hanna Raaska,
• Jaakko Matomäki,
• Jari Sinkkonen,
• Helena Lapinleimu

• Published: January 25, 2021
• https://doi.org/10.1371/journal.pone.0245786

These findings contribute to the existing knowledge in the field of pediatrics and adolescent medicine. The team’s research sheds light on important factors that impact the health and well-being of young individuals.

Contextual Background

Research Focus

Upon arrival in a new country, internationally adopted children frequently harbor intestinal parasites and display more behavioral concerns compared to their biological counterparts. This study investigates whether initial intestinal parasite infections in internationally adopted children upon their arrival in Finland correlate with subsequent behavioral and emotional issues.

Study Methodology

Data from the Finnish Adoption Study (FinAdo) were utilized, involving parental reports on all internationally adopted children under 18 years (n = 1450) arriving in Finland between 1985 and 2007. A subset of 1293 families provided comprehensive information on the adoptees’ background, initial parasitic status, and behavioral symptoms approximately 5 years post-arrival (mean age = 7.8 years). Behavioral and emotional concerns were gauged using the Child Behavior Checklist (CBCL), with statistical analyses performed through linear regression.

Findings and Implications

Among the 1293 families, parents of 206 adopted children disclosed initial intestinal parasite infections. Children with parasitic infections exhibited higher CBCL problem scores than those without parasites (p < 0.001). The link between initial parasite infections and later behavioral issues surpassed associations with other measured factors, except disabilities.

Limitations and Future Prospects

Limitations included the absence of a comparative non-adopted group without defined parasite infections. Specific parasite effects and multiple environmental contributors to behavioral issues were not fully explored. However, the study suggests early childhood parasite infections could impact later psychological well-being, even in low-prevalence settings, supporting further research into the gut-brain axis theory.

Citation: Heikkilä A-R, Elovainio M, Raaska H, Matomäki J, Sinkkonen J, Lapinleimu H (2021) Intestinal parasites may be associated with later behavioral problems in internationally adopted children. PLoS ONE 16(1): e0245786. https://doi.org/10.1371/journal.pone.0245786

Editor: Adler R. Dillman, University of California Riverside, UNITED STATES

Received: March 25, 2020; Accepted: December 29, 2020; Published: January 25, 2021

Data Availability: Due to GDPR regulations, data cannot be publicly shared. Access is governed by Finnish laws and the Health and Social Data Permit Authority.

Funding: The study received funding from various sources detailed in the manuscript.

Competing interests: Consultation fees were received by Helena Lapinleimu; the other authors declared no conflicts of interest.

Biological and Neurological Insights

Internationally adopted children commonly experience growth delays and behavioral issues upon relocation. Parasite infections, prevalent among adoptees from underprivileged regions, can disrupt gut-brain axis function and alter microbiota composition, potentially contributing to long-term psychological effects. Future studies are necessary to explore the persisting risks associated with early parasite exposure post-treatment and relocations.

Additionally, research has shown that early life stress, such as institutionalization or neglect, can have profound effects on brain development and neurological functioning in adopted children. These stressors can lead to alterations in neurobiological pathways, affecting cognitive abilities and emotional regulation. Understanding these biological and neurological mechanisms is crucial in developing targeted interventions to support the healthy development of internationally adopted children.

Study Background and Methodology

Study Overview

The FINnish ADOption (FinAdo) study surveyed all internationally adopted children in Finland between 1985 and 2007. Data collection included questionnaires on child-related and family-related factors, alongside behavioral assessments using the CBCL. The study aimed to investigate the impact of initial parasite infections on later behavioral problems among internationally adopted children.

Approval for the study was obtained from the Ethics Review Committee of the Hospital District of Southwest Finland, with parental consent secured for participation.

Participant Details

Child-related factors.

Collected information included the child’s gender, age at adoption, birth country, and pre-adoption history. Parasitic status upon arrival, medical diagnoses post-adoption, and parental-reported behavioral details were also considered.

Upon their arrival in Finland, internationally adopted children undergo health assessments, which include testing for parasite infections through stool examinations. Parents are required to attach the results to a questionnaire.
When analyzing family-related factors, parents are asked about their marital status, socioeconomic status, and overall health. Socioeconomic status is classified into four categories based on the profession of the family member with the highest status, while marital status is split into two categories.
To assess behavioral problems, the Child Behavior Checklist (CBCL) is used to measure emotional and behavioral issues, providing total scores and separating them into internalizing and externalizing symptoms. Higher scores indicate a higher presence of problems. The data is then analyzed using statistical software, with a significance level set below 0.05, and various variables are studied using regression analysis in four steps.
Out of 1293 children screened, 206 were found to have intestinal parasites upon adoption, with Giardia lamblia being the most common. Older children were more likely to have parasites, and parasitism was linked to sub-standard height.
Children infected with intestinal parasites upon adoption showed higher CBCL problem scores compared to uninfected children. The association with CBCL categories did not vary between parasite types, and several interaction effects were observed.
These infections were also linked to higher CBCL scores later in life, potentially due to changes in the gut-brain axis and inflammation. The disruption in absorption processes caused by intestinal parasitic infections may contribute to behavioral issues through micronutrient deficiencies like iron.
Lastly, the study highlighted that earlier parasite infections were associated with higher CBCL problem scores in all categories, and children adopted from certain regions may be more affected due to local parasites or other risk factors. The study emphasized the importance of screening and treating parasitic infections in internationally adopted children, as they may impact behavioral outcomes.