Why adopted children may be at an increased risk of being diagnosed with ADHD?
Attention Deficit Hyperactivity Disorder (ADHD) is the diagnostic label currently used to describe one of the most frequently diagnosed neurodevelopmental disorders in children. According to the American Association of Psychiatry (APA), the prevalence of this disorder reportedly affects around 5% of the population. (The Diagnostic and Statistical Manual of Mental Disorders, 2013)
ADHD’s primary causes are still unclear. What is known is that it is a heterogeneous and complex neurobiological disorder. Complicating matters further is the fact that it cannot be explained by a single cause but rather must be understood as relating to a series of genetic conditions in combination with other environmental factors.
It seems that genetic contribution plays an important role in ADHD diagnoses. According to various studies in families, twins, and adopted children, genetics plays a very important role in the transmission of ADHD intergenerationally. It is estimated that 70% of these causes can be attributed to genetic factors (Faraone et al., 2005). Socioeconomic factors, coupled with disorganized family dynamics and the effects institutionalization has on family upbringings, all tend to increase the risk factors associated with this condition (Jacobs, Miller & Tirella., 2010).
The prevalence of ADHD in adopted children is higher than in non-adopted children. In 1990, Verhulst, Althaus & Versluis-Den Bieman concluded a higher incidence of ADHD in the adopted group. This data coincides with that of other documented studies. For instance, Fernández et al (2017) speak of a prevalence of ADHD 15 times higher among adopted children when compared to non-adopted children.
More recent studies have also concluded that this prevalence in the diagnosis of adopted children continues to persist when compared to the general population, finding a 25 to 50% increase in adopted children (Abrimes et al 2012)
The postnatal and prenatal environment of adopted children, which may be inadequate for promoting healthy psychological development, may present one of the keys to understanding the increased incidence of such disorders within these subgroups. Broken families with few economic resources and overcrowded institutions where children are poorly attended, both physically and emotionally, also tend to produce higher incidents of new diagnoses. This essay will attempt to explore the possible reasons why adopted children are more likely to have attention deficit hyperactivity disorder (ADHD).
What is ADHD and what are its risk factors?
According to the American Psychiatric Association, Attention Deficit Hyperactivity Disorder is characterized by its neurobiological nature which typically originates in childhood and implies a pattern of attention deficit, hyperactivity, and/or impulsivity. ADHD is often recognized in children when primary education begins, coinciding with difficulties in school performance and the appearance of certain social disorders.
In terms of prevalence, ADHD is one of the most frequently diagnosed psychiatric disorders in children; even higher than schizophrenia and bipolar disorder (Casas et al, 2009). It is estimated that the global prevalence of ADHD affects around 5.29% of school-age children.
Due to the complexity of ADHD, a single cause cannot be identified. It is a heterogeneous disorder with different subtypes, resulting from varied combinations of certain risk factors acting in unison with one another. However, it has been determined in numerous medical studies that these causes are mainly due to genetic and environmental factors (prenatal, perinatal, and postnatal) (American Academy of Pediatrics, 2001).
This large genetic component being a determining factor in new diagnoses has been shown in several studies. According to Faraone and colleagues, the direct family members of people with ADHD are up to eight times more likely to be diagnosed than relatives of people not affected by this condition. What makes this point particularly clear are the numerous medical studies involving twins, all of which show higher rates of ADHD heredity, ranging from 71 to 90%.
On the other hand, there are also psychosocial factors that may promote the appearance of ADHD. Factors relating to pregnancy and childbirth most often associated with new diagnoses are evident in the numerous documented studies observing the effects smoking has on pregnancy with regard to low birth weight and maternal stress (Froehlich et al., 2009). Alcohol abuse could also cause dysfunction and altered mental functioning, including Fetal Alcohol Syndrome, which has been shown to display some of the main symptoms typically associated with ADHD (Froehlich et al., 2009).
Stress, anxiety, and prenatal maternal depression are also significant factors shown to increase the risk of adverse outcomes in childhood development. Emotional problems and deterioration in cognitive development all tend to lead to symptoms associated with hyperactivity and attention deficit disorder (ADHD). Although genetics and postnatal care clearly have an effect on early childhood development, studies show prenatal maternal depression and anxiety to be amongst some of the largest contributors to new diagnoses. It is estimated that between 10 to 15% of the burden is attributable to factors related to poor prognosis (Glover, 2015).
These numerous risk factors may be more problematic in adopted children since the vast majority are not aware of their biological parents' background or medical history. Furthermore, vital experiences in the first years of life should always be considered as many come from difficult sociological environments.
Prevalence of ADHD in adopted child
Many authors have concluded that adopted children are more likely to have an increased frequency of ADHD-associated symptoms when compared to their non-adopted counterparts. In a study published in the Journal of Abnormal Child Psychology testing a sample of 808 adopted children found that 21% of those examined had ADHD-associated symptoms. In addition to this, various other risk factors are directly correlated with this disorder, such as any abuse or neglect experienced prior to adoption. Furthermore, the age of adoption and the number of foster homes the child has been placed in since their adoption also play a factor. (Simmel, Brooks, Barth, & Hinshaw., 2001).
In another study, a sample of 200 children diagnosed with ADHD found that 17% of those diagnosed were adopted (Deutsch, CK, Swanson, JM, Bruell, JH, Cantwell, DP, Weinberg, F., & Baren, M. 1982). Following suit, another study including a sample of 37 children found 'significant problem' scores for hyperactivity and ADHD traits among 14% of those who had been adopted. Furthermore, other negative correlations were present in those who had been adopted later in life. (Jacobs et al., 2010).
This prevalence seems to be more characteristic in adopted children from Eastern Europe. A study by Gunnar & Van Dulmen in 2007 found more behavioral problems in adopted children from Russia when compared to adopted children from other parts of the world. In these cases, the possibility of prenatal exposure to alcohol, common in many of those countries, must be taken into consideration. However, a study by Jacobs et al, which included 37 adopted children from different parts of the world, did not find significant differences between the prevalence of ADHD symptoms in relation to the patient’s country of origin.
Prenatal alcohol exposure
Fetal Alcohol Spectrum Disorders (FASD) constitute a group of conditions that may arise in a person whose mother drank alcohol heavily during pregnancy. These effects can include physical, behavioral, and learning problems. Commonly, people with FASD tend to suffer from a combination of these problems. FASD is associated with cognitive and behavioral alterations which, in part, are derived from the psychosocial environment where childhood development initially occurs (O'Connor & Paley., 2009).
It seems very plausible that this type of disorder correlates to increased incidents of ADHD. In a study by Fernandez et al., 2017, they found significant relationships between FASD and attention-deficit/ hyperactivity disorder (ADHD) in any of its subtypes, with a 60% increase in diagnoses among adopted children. It is unknown why the gestation process of the biological mother plays a role in the frequency of diagnoses, although normally these subjects have been assessed as a risk group due to the various circumstances arising during pregnancy. One study found that alcoholism tended to occur more frequently among children whose parents had been incarcerated, especially in Eastern Europe (Johnson., 2002). These results differ according to the study. Possible prenatal exposure to alcohol may be one of the most plausible explanations for a higher incidence of ADHD in adopted children.
A study by Langred and colleagues in 2010 examined 71 adopted children from Eastern Europe to determine whether or not they suffered from Fetal Alcohol Syndrome (FAS). The results concluded that 52% of children studied had this disorder. Researchers also found that these Children presented different behavioral problems, with ADHD having one of the highest incidence rates, with 52% being from Western populations. The prevalence of FAS is 3 to 7 cases per 1000 children; however, higher rates have been recorded when less developed subpopulations like South Africa were investigated, finding a prevalence of 68 to 89 cases. (May et al., 2007).
References
- Abrines, N., Barcons, N., Marre, D., Brun, C., Fornieles, A., & Fumadó, V. (2012). ADHD-like symptoms and attachment in internationally adopted children. Attachment & human development, 14(4), 405-423.
- American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub.
- Bush, G., Spencer, T. J., Holmes, J., Shin, L. M., Valera, E. M., Seidman, L. J., ... & Biederman, J. (2008). Functional magnetic resonance imaging of methylphenidate and placebo in attention-deficit/hyperactivity disorder during the multi-source interference task. Archives of General Psychiatry, 65(1), 102-114.
- Deutsch, C. K., Swanson, J. M., Bruell, J. H., Cantwell, D. P., Weinberg, F., & Baren, M. (1982). Overrepresentation of adoptees in children with attention deficit disorder. Behavior Genetics, 12(2), 231-238.
- Faraone, S. V., Perlis, R. H., Doyle, A. E., Smoller, J. W., Goralnick, J. J., Holmgren, M. A., & Sklar, P. (2005). Molecular genetics of attention-deficit/hyperactivity disorder. Biological psychiatry, 57(11), 1313-1323.
- Fernandez-Jaen, A., Lopez-Martin, S., Albert, J., Martin, D. F. M., Fernandez-Perrone, A. L., Calleja-Perez, B., & Lopez-Arribas, S. (2017). Attention deficit hyperactivity disorder: from a neurodevelopmental perspective. Revista de neurologia, 64(s01), S101-S104.
- Froehlich, T. E., Lanphear, B. P., Auinger, P., Hornung, R., Epstein, J. N., Braun, J., & Kahn, R. S.(2009). Association of tobacco and lead exposures with attention-deficit/hyperactivity disorder. Pediatrics, 124(6), e1054–e1063,
- Glover, V. (2015). Prenatal stress and its effects on the fetus and the child: possible underlying biological mechanisms. In Perinatal programming of neurodevelopment (pp. 269-283). Springer, New York, NY.
- Gunnar, M. R., & Van Dulmen, M. H. (2007). Behavior problems in postinstitutionalized internationally adopted children. Development and Psychopathology, 19(1), 129-148.
- Jacobs, E., Miller, L. C., & Tirella, L. G. (2010). Developmental and behavioral performance of internationally adopted preschoolers: A pilot study. Child Psychiatry & Human Development, 41(1), 15-29.
- Johnson, D. E. (2002). Adoption and the effect on children's development. Early human development, 68(1), 39-54.
- Maclean, K. (2003). The impact of institutionalization on child development. Development and Psychopathology, 15(4), 853-884.
- May, P. A., Gossage, J. P., Marais, A. S., Adnams, C. M., Hoyme, H. E., Jones, K. L., ... & Hendricks, L. (2007). The epidemiology of fetal alcohol syndrome and partial FAS in a South African community. Drug and alcohol dependence, 88(2-3), 259-271.
- O'Connor, M. J., & Paley, B. (2009). Psychiatric conditions associated with prenatal alcohol exposure. Developmental disabilities research reviews, 15(3), 225-234.
- Rutter, M., Andersen-Wood, L., Beckett, C., Bredenkamp, D., Castle, J., Groothues, C., ... & O'Connor, T. G. (1999). Quasi-autistic patterns following severe early global privation. The Journal of Child Psychology and Psychiatry and Allied Disciplines, 40(4), 537-549.
- Sprich, S., Biederman, J., Crawford, M. H., Mundy, E., & Faraone, S. V. (2000). Adoptive and biological families of children and adolescents with ADHD. Journal of the American Academy of Child & Adolescent Psychiatry, 39(11), 1432-1437.
- Simmel, C., Brooks, D., Barth, R. P., & Hinshaw, S. P. (2001). Externalizing symptomatology among adoptive youth: Prevalence and preadoption risk factors. Journal of Abnormal Child Psychology, 29(1), 57-69.
- Verhulst, F. C., Althaus, M., & Versluis-Den Bieman, H. J. (1990). Problem behavior in international adoptees: I. An epidemiological study. Journal of the American Academy of Child & Adolescent Psychiatry, 29(1), 94-103.