The following is part 1 of a 2 part series examining Schizophrenia and Adopted Children. Stay tuned for Part 2 early next week.
Families considering adoption often wonder about the genetic risk a child may have for a mental illness. One of the most frightening of all the mental illnesses is schizophrenia, and if a child is at what may be considered a genetic risk for the disorder, families are often not prepared to take this risk and proceed with the adoption (Kestler, Bollini, Hochman, Mittai, & Walker, 2012). But a birth mother, birth father or other close relative having the condition does not necessarily mean the child is very likely to have the disorder. There is no one identified cause or even one common trait that is characteristic of all those with schizophrenia.“Schizophrenia patients vary in symptom profiles, developmental histories, family backgrounds, cognitive functions, and even brain morphology and neurochemistry” (Kestler et al., p. 247).
Even with this lack of understanding of schizophrenia, it is known that genetics do play a role. For example, identical twins have the highest concordance rates of any two family members; yet the rate is only 25 to 50% (Kestler et al.) that if one twin has schizophrenia the other one will as well. Considering that identical twins share 100% of the same genetic material, there are obviously other factors that contribute to the expression of schizophrenia (Kestler et al.).
Older studies of those adopted, indicate that the disease appears to be more strongly linked to genetic rather than environmental factors (Kestler et al.). In an adoption study published in 2000, researchers noted that genetics played a significant factor in placing a person at risk (Ingraham & Kev, 2000). Of the 190 adult adoptees who had a biological mother with narrowly defined schizophrenia, the adoptees had a 5.34% risk of schizophrenia compared to 1.74% of those in which the adoptee had low genetic risk for schizophrenia (Tienari et al., 2006). For adoptees whose birth mother had broad spectrum schizophrenia, the rate among the adoptees for schizophrenia spectrum disorder, including Schizotypal personality disorder, was 22.36% (Tienari et al). These differences are statistically significant (Tienari et al.).
A more recently published 21-year follow-up adoption study, in which adoptees were assessed for the prevalence of schizophrenia based on the adoptive family’s level of dysfunction and the adoptees’ genetic risk for schizophrenia, it was found that for those adopted with a genetic predisposition to schizophrenia, the adoptive home environment could be a contributing factor to or a protective factor against having schizophrenia (Tienari et al). The authors of this study note that former studies that demonstrated a genetic link to schizophrenia among adoptees did not take into consideration the adoptive families’ levels of function. This study found that adoptees with no known genetic risk of schizophrenia as defined by the DSM-III-TR and reared in functional adoptive families showed 0% risk of schizophrenia (Tienari et al.). Adoptees who were considered at high genetic risk but reared in healthy adoptive families, there was a 1.49% risk of schizophrenia (Tienari et al.). On the other hand, low risk adoptees reared in dysfunctional families had a nearly 5.0% risk of schizophrenia, and adoptees who were at a high genetic risk and raised in dysfunctional families were at a 13% risk for the disorder (Tienari et al.).