Marcy Student Shippensburg University Adoptive and Biological Families of Children and Adolescents With ADHD

The Problem Attention Deficit Disorder (ADD), presently known as Attention Deficit Hyperactivity Disorder (ADHD) is a childhood psychiatric condition that includes symptoms of inattention, hyperactivity, and impulsivity (“Attention Deficit Disorder,” 1995). Although it is more common in boys, ADHD is thought to affect 5% of school-age children (Biederman, Crawford, Faraone, Mundy, and Sprich, 2000). There were many theories as to the cause of ADHD that have included everything from head injuries to fluorescent lights. Today, however, it is widely believed that there is a biological basis for the disorder. Studies of the brain suggest that individuals with ADHD have an abnormality in the cerebral cortex, an area in the brain important for controlling attention and planning. Positron emission tomography (PET), suggests individuals with ADHD use an abnormally small amount of energy in several regions of the brain including the cerebral cortex. Other studies of the brain show abnormalities in the corpus callosum, which is an area that controls the suppression of automatic responses. Other theories involve problems in the functioning of the reticular activating system

(RAS) which has an arousal function (“Attention Deficit Disorder,” 1995). In addition to studies showing abnormalities in the brain, research suggests there is a genetic influence present in the etiology of ADHD. Studies comparing identical and fraternal twins have indicated an involvement of genes (“Attention Deficit Disorder,” 1995). In addition to twin studies, adoption studies have been conducted to investigate whether or not there is a genetic influence on the development of ADHD. Although adoption studies have supported a genetic contribution to the development of ADHD, interpretation of their findings is limited. Two such studies used definitions of ADHD that were very different from the DSM (Diagnostic and Statistical Manual) definitions. A third study did not include operational criteria for diagnosis (Biederman, 2000). Therefore, the present adoption study was prepared to avoid these flaws. The present study attempts to answer the question of whether or not ADHD is a genetic disorder by comparing adopted and nonadopted ADHD probands (participants of a genetic study). The researchers

hypothesized that the rates of ADHD (and associated disorders) in the adoptive relatives of the adopted ADHD probands would be lower than those found in the biological relatives of the nonadopted ADHD probands. Furthermore, the researchers hypothesized that the rates of ADHD (and associated disorders) in the adoptive relatives of the adopted ADHD probands would be similar to those observed in the biological relatives of the control probands (Biederman, 2000). It is important to learn more about the etiology of ADHD in order to develop prevention strategies and better treatments. If there is a genetic influence, individuals with the disorder or who have ADHD in their family history are more likely to have children with the disorder as well. Therefore, it is important to learn as much as possible in order to take necessary precautions.

Methods Participants “Adopted ADHD”- The adopted sample consisted of 25 white children (both male and female) between the ages of five and 18 years in whom DSM-III-R ADHD had been diagnosed. These children were adopted within their first year of life by families of the same cultural background. Their 62 first-degree adoptive relatives (50 parents and 12 siblings) also made up this sample. Siblings who were not full biological children of the adoptive parents were not included in statistical analyses. These subjects were recruited from referrals to a medical center at a major university. “Biological ADHD”- These children were referred to the same medical center as the adopted sample and were assessed using an identical assessment battery. This sample consisted of 101, nonadopted, males and females who had been diagnosed with DSM-III-R ADHD. Their 310 biological first-degree relatives (198 parents and 112 siblings) were also included in this sample.

“Controls”- The control group consisted of 50, nonadopted, males and females in whom ADHD was not diagnosed. Their 153 biological first- degree relatives (99 parents and 54 siblings) were also included. Nonadopted participants were selected to attain a similar age, gender, and social class distribution across groups. Stimuli A variety of assessment batteries were used for the psychiatric assessment of probands and first-degree relatives. One such battery is The Schedule for Affective Disorders and Schizophrenia for School-Age Children- Epidemiologic version, 4 th edition (K-SADS-E). Adults were given the Structured Interview for DSM-III-R. In order to evaluate socio- economic states (SES) the Four Factor Index of Social Status was used. Families were assigned a SES level that ranged from one (highest) to five (lowest). For those probands and first-degree relatives who met all DSM-III-R diagnostic criteria, the DSM-III-R Global Assessment of Functioning (GAF) and the appropriate score was assigned.

Procedure Psychiatric assessments of probands and first-degree relatives were conducted by clinical raters. These raters used the K-SADS-E and the Structured Interview for DSM-III-R to assess probands and first-degree relatives. These raters were blind to the diagnostic and adoptive status of each proband. They were also unaware of which child in each family was the proband. A panel of board-certified psychiatrists made final diagnostic and GAF score assignments after a blind review. Probands and their relatives who met all DSM-III-R diagnostic criteria were assigned definite diagnoses. Diagnoses were considered definite only if the committee agreed that the criteria for the diagnoses were met to a degree that would be clinically meaningful. The diagnosis of major depression was made only when it was determined that there was severe impairment. Additionally, a category was created by the researchers termed multiple anxiety disorders which included participants who had at least two anxiety disorders. Participants with only one anxiety disorder were not included in analyses. This was done so that only participants with

clinically significant levels of depression and anxiety were obtained. The data of adoptive first-degree relatives were compared with the data of the first-degree biological relatives of the ADHD and control probands. Omnibus 3 X 2 (chi- square) analyses were conducted for the diagnostic variables. The omnibus test was followed by 2 X 2 (chi-square) test if it was significant. Logistic regression was performed to statistically correct for the fact that siblings of probands were not statistically independent of each other due to shared genetic factors. An overall F test was obtained by analysis of variance and if significant, the F test was followed by pairwise t tests. The p value for all tests was set at.05 and only the results with a p value less than.05 were considered statistically significant.

Results A significant difference was found between the biological parents and siblings of biological ADHD probands when compared with the adopted ADHD and control group. It is clear that ADHD is familial in biological parents and siblings of biological ADHD probands (Figure 1). On the other hand, no significant differences were found in the rate of ADHD in parents and siblings of adopted children compared with parents and siblings of control probands. A significant difference was found between parents of biological ADHD probands and parents of adopted ADHD probands and control probands. Significantly higher rates of generalized anxiety disorder, overanxious disorder, and severe major depression were found in parents of biological ADHD probands compared to the other two groups. Very few disorders were found in the siblings of the adopted probands (one child with encopresis, one child with ADHD, and two children with language disorder). The same cannot be said for the siblings of the biological ADHD probands. Thirty-one percent exhibited ADHD, 13%

displayed severe major depression, 22% had oppositional disorder, and 17% displayed multiple anxiety disorders and other associated disorders. The GAF scores for parents and siblings of adopted ADHD and control probands were higher (less impaired than those of parents and siblings of the biological ADHD probands (Figure 2). There were no significant differences in the demographic characteristics of all three groups of probands (Table 1).

Discussion The results of this study confirmed the hypothesis that the rates of ADHD in the adoptive relatives of the adopted ADHD probands would be similar to those observed in the biological relatives of the control probands. The researchers found that the rate of ADHD in adoptive parents of adopted children with ADHD was low, suggesting that ADHD is a genetic disorder. Furthermore, this rate was indistinguishable from the rate found in parents of children who do not have ADHD (non-ADHD controls). Both these rates were significantly lower than the rate of ADHD in parents whose biological children had ADHD. Because the rate of ADHD (and associated disorders) in parents whose biological children had ADHD was significantly higher than the other groups, this also suggests a genetic component to the disorder. The results of this study support the theory that ADHD has a genetic etiology. It also adds to the body of other research that also suggests a genetic influence. Although this study supports a genetic influence, it does not suggest a person’s environment is not important. Like other disorders with a genetic component the environment also plays a role.

Although one may be predisposed to ADHD, it may require a certain environment in order to show itself. In addition to the role of the environment, the details of which genes are involved in this genetic component are also unknown. More research must be done to learn the which genes may predispose a person to ADHD.

References Attention Deficit Disorder. (1995, May). Copy Editor, 11, Biederman, J., Crawford, M., Faraone, S., Mundy, E., and Sprich, S. (2000). Adoptive and biological families of children and adolescents with adhd. Journal of the American Academy of Child and Adolescent Psychiatry, 39,

Table 1 Demographics of participants Adopted ADHD (n= 25) Biological ADHD (n= 101) Controls (n= 50) Age, mean (SD) 11.4 (4.2)10.6 (3.2)10.9 (3.6) SES, mean (SD) 1.5 (0.5)1.9 (1.0)1.9 (0.9) No. (%) intact23 (92)70 (69)37 (74) No. (%) females 6 (24)24 (24)12 (24) The above table shows the demographic characteristics of the three research groups. All results were nonsignificant.

Figure 1 Rates of attention-deficit hyperactivity disorder (ADHD) and associated disorders in parents and siblings of probands.

Figure 2 Mean Global Assessment of Functioning (GAF) scores for parents and siblings of probands.