ACC and ADHD: Are They Related?

Tina Everett
Kathryn J. Schilmoeller
Gary L. Schilmoeller

© Reproduction must be with permission of the authors
Presented at the California ACC conference, Yorba Linda, CA, August 2001.

Thank you to all who filled out this survey on short notice. Your help is essential to finding some of the puzzle pieces that help us understand this phenomenon of agenesis of the corpus callosum. Thank you, too, to the many people who sent contributions to The ACC Network. Those gifts helped support this project.


Agenesis of the Corpus Callosum (ACC) has long been a mysterious condition with many questions and very few answers. Some of the effects associated with ACC puzzle even the most established professionals and scholars. Much of the research has focused on specific brain functioning or medical aspects that appear in people with ACC (e.g., Lassonde & Jeeves, 1994). Only recently have researchers begun to look specifically at the psychosocial aspects of ACC (e.g., Brown & Paul, 2000). And we have found only two published case studies that study children with ACC as they function in school settings (Ritter, 1981; Sorenson, 1997).   As a result, relatively little information about how children with ACC behave in schools, homes, and other social settings is available to families. Families and professionals alike have many unanswered questions and seek answers for the sake of those who have this condition.

The ACC Network, founded by Gary and Kathy Schilmoeller, sponsors an electronic discussion group (ACC Listserv) that allows many of these families to contact each other and provide support as they struggle through the mystery together.   While listserv participants comment on many different topics, one topic in particular intrigued us. Many listserv participants report that children with ACC also manifest behaviors associated with the common childhood disorder called Attention Deficit Hyperactivity Disorder (ADHD) [sometimes also referred to as ADD or Attention Deficit Disorder].   For example:

  • “…we have had difficulty keeping [our child] focused in school…he is extremely impulsive…”
  • “…she cannot focus [or] sit still and needs constant redirection on the simplest of tasks especially when there is a break in her routine…”
  • “…the doctor feels that [my child] has ADD. She also feels that this has nothing to do with the ACC. She feels that with medicine [my child] would be able to focus better… I thought these were all symptoms of her ACC…”
  • “…what is actually ADHD or a symptom of the ACC… well… your guess is as good as mine…”

These comments lead to the question, “Is there a relationship between ACC and ADHD?”

To help these families and professionals gather information about the behavioral tendencies of children with ACC, we set out to better describe the relationship between ACC and ADHD. Specifically, we wanted to answer several questions: (1) How many children have a dual diagnosis of ACC and ADHD? Related to this, do children with ACC who do not have the dual diagnosis display behavioral symptoms that could meet diagnostic criteria for ADHD? (2) Do children with partial ACC score differently on the ADHD assessments than children with complete ACC? (3) Are there gender differences in the incidence of ADHD behavioral symptoms? (4) What are the perceived advantages and disadvantages of dual-diagnosis?


We surveyed families of school-age children with ACC involved with The ACC Network. Some families returned surveys but noted that the school-age child in their family was too severely delayed for the questions to be at all relevant. Families of 383 children returned surveys with usable information. The mean age of children was 9.33 years. Twenty-four percent attended some type of preschool program, 69% attended elementary grades, and 6 % attended high school. Of all participants, 53% were male, and 47% were female. Mothers most frequently (84.7%) completed the survey on behalf of the child. Fathers represented 5.5% of the respondents. On average, caregivers completing the survey had completed between two and three years of post-secondary education.

The survey included two commonly used ADHD assessment checklists. In each checklist, scoring criteria permitted us to look at three aspects of ADHD: 1) ADHD-I, indicating primarily inattention; 2) ADHD-H, indicating primarily hyperactivity/impulsivity; and 3) ADHD-C, indicating a combination of both inattention and hyperactivity/impulsivity.

The first checklist was taken from the Diagnostic and Statistical Manual IV (Frances, et. al., 1994) and included 18 items requiring the caregiver to rate the frequency of particular behaviors on a four-point Likert scale—choosing between “not at all,” “just a little,” “pretty much,” or “very much.”    Sample items include: “often fails to give close attention to details or makes careless mistakes,” “often fidgets with hands or feet or squirms in seat,” and “often interrupts or intrudes on others.”

The second checklist was derived from the Swanson, Nolan, and Pelham Questionnaire (SNAP–IV), constructed to diagnose ADHD as well as Oppositional Defiant Disorder (ODD). The SNAP-IV has been revised along with the DSM over the past twenty years. As the defining qualities of the disorder are modified, so is the checklist. Consequently, much of the wording is the same as found in the DSM-IV. The survey used in this study included the first 40 items of the SNAP-IV, of which only 20 address attention deficit, hyperactivity, and impulsive behaviors. As with the DSM-IV checklist, the SNAP-IV requires respondents to rate the frequency of the child’s behaviors on a four-point Likert scale, choosing between “not at all,” “just a little,” “quite a bit,” and “very much.”

On the survey, we also included open-ended questions asking respondents to indicate positive consequences, negative consequences, and additional comments regarding the diagnostic label of ADHD. We coded and analyzed the returned surveys using the SPSS system for statistical analyses.


(1) How many children have a dual diagnosis of ACC and ADHD. Related to this, do children with ACC who do not have the dual diagnosis display behavioral symptoms that could meet diagnostic criteria for ADHD?

Item-by-item analyses indicate that children with ACC do tend to display behavioral symptoms similar to those associated with ADHD.   There are a couple of different ways to address this issue. First, of the 383 surveys of children with ACC, 74 (19.3%) represented children who had a diagnosis for both ACC and ADHD (see Figure 1). Second, setting aside these official diagnoses, we analyzed the surveys to see what percentage of all 383 children met any ADHD criterion – ACHD-I (inattentive), ADHD-H (hyperactive), or ADHD-C (combined). Analyzing each of these possibilities, nearly two-thirds of all the children (65.5%) met at least one criterion for ADHD using the DSM-IV questions (see Figure 2, left bar). And almost one-half (49.7%) met at least one criterion for ADHD using the SNAP-IV questions (see Figure 2, right bar). Because these figures include the 74 children who have an official diagnosis of ADHD and therefore could inflate the scores, we analyzed only the 309 surveys of the children who had not been diagnosed officially with ADHD. Of these 309, 57.9% meet at least one or more of the DSM-IV criteria and 42.9% meet at least one or more of the SNAP-IV criteria (see Figure 3). Thus, between four and six out of ten children who were diagnosed with ACC but not ADHD actually showed behavior patterns that met one or more of the criteria for two of the instruments that are used to diagnose ADHD.

We were interested in the specific pattern of behaviors exhibited by the children who did not have an official ADHD diagnosis. Of the 309 children who did not have an official ADHD diagnosis, more than half (52.5%) met the DSM-IV scoring criterion for an ADHD-I (primarily inattentive) diagnosis. About one in four of those who did not have the official ADHD diagnosis also met the DSM-IV scoring criteria for the ADHD-H (primarily hyperactive/impulsive) diagnosis (28.5%) and for ADHD-C (combined hyperactive and inattentive) diagnosis (23.7%) [ see Figure 4, left bars].

Using the SNAP-IV items, about one-third (36.9%) of the children met the scoring criterion for the ADHD-I diagnosis. This is slightly lower than the percentage identified using the DSM-IV criterion. On the other hand, the percentages of children meeting the SNAP-IV criteria for ADHD-H diagnosis (25.9%) and ADHD-C diagnosis (27.5%) are very similar to the results of the DSM-IV analysis. (See Figure 4, right bars.)

Of particular interest is the fact that the largest percentage of children who meet any ADHD criterion for either the DSM-IV or SNAP-IV items meet the criterion for ADHD-I. Thus, inattention characterizes the behavior of these children with ACC more than hyperactivity or impulsivity. This prevalence may represent an inability to focus on academic content and instructions as presumed by an ADHD diagnosis. Alternatively, it may represent evidence for the suggestion of Schilmoeller and Schilmoeller (2000) that school-age children with ACC often may know more or attend to more than they are capable of expressing through current standard measures. If the latter is the case—that children with ACC appear to be inattentive but actually are often attending and processing large quantities of information without being able to produce it reliably on written or verbal tests commonly used—then intervention strategies might be different than those recommended for children with ADHD.

(2) Do children with partial ACC score differently on the ADHD assessments than children with complete ACC?

No difference in behaviors reported by families of children with partial ACC vs. children with complete ACC were found in this study.

(3) Are there gender differences in the incidence of ADHD behavioral symptoms?

In our sample, for children who did not have the ADHD diagnosis but met the DSM-IV behavioral criteria for ADHD, 54% were males and 46% were females. For the SNAP-IV checklist, 51% were males and 49% were females. On the other hand, for the 74 children with the dual ACC-ADHD diagnosis, 65% were male and 35% were female. Boyles & Contadino (1997) note that ADHD generally is diagnosed more frequently in males than females among young children but that the gender distribution is about equal among adults. We show the greater incidence of males in the children with the official ADHD diagnosis, but the more equal distribution among the children have only the ACC diagnosis but who exhibit ADHD behavioral patterns. Clearly more work is needed in this area.

(4) What are the perceived advantages and disadvantages of dual-diagnosis?

Three hundred and forty-two respondents offered comments to the open-ended questions on the survey. Of these, 57 felt that an ADHD label would make special services more accessible; 49 felt that an ADHD label would allow access to beneficial medication; 44 commented that the label provided an increased understanding or an answer to “why” the atypical behavior exists; and 29 felt that the label would make the school setting more manageable through teacher assistance. These perceived benefits, if found through further research to be accurate, could clearly impact the lives of children with ACC. Caregivers might seek the ADHD label to obtain additional benefits and services.

The same set of responses to the open-ended questions also identified potential risks of dual-diagnosis. Respondents identified three major potential risks: (1) 63 respondents wrote that the ADHD diagnosis is uncertain (i.e., too easily diagnosed, assessed using subjective measures, and potentially over-diagnosed); (2) 69 respondents wrote that the ADHD label could lead to medicinal risks (i.e., children are too easily medicated, medications are long-term, and side effects are unknown); and (3) 63 respondents felt that the stigma of the label would lead to decreased expectations or poor self-image. These perceived disadvantages or risks of an ADHD label cause caregivers to hesitate when this additional diagnosis is offered.


Approximately one-fifth of the school-age children in our sample already had an official dual diagnosis of ACC and ADHD. However, one-half to two-thirds of the children who did not have a diagnosis of ADHD met the behavioral criteria used for the ADHD diagnosis, depending on whether the SNAP-IV or DSM-IV was used. The children in this group most frequently met the behavioral criterion for the Inattentive rather than the Hyperactive or Combined subgroups. No differences were found in this study when looking at those with complete ACC versus partial ACC. Finally, caregivers perceived advantages including potential access to more services and disadvantages such as the side effects of medication when considering the effects of a dual diagnosis of ACC and ADHD.

In conclusion, the results of this study suggest that there is indeed a relationship between ACC and ADHD. Our hope is that these findings will provide some beginning answers as parents and professionals seek to make informed decisions concerning children with ACC who exhibit ADHD-like behavioral symptoms. It is important to note that the official diagnosis of ADHD involves more than simply meeting the scoring criteria of either the DSM-IV or SNAP-IV checklists. The official diagnosis involves the person exhibiting these behavioral patterns in two or more settings for a duration longer than six months. Thus, our results are preliminary rather than an exhaustive answer to the question of the relationship between ACC and ADHD.

Many unanswered questions remain. Among them are:

  • Are the ADHD behavioral symptoms caused by the ACC or are they only associated with ACC and actually caused by some other condition?
  • Do those with ACC actually attend and absorb more than the “inattentive” behavior would suggest?
  • Are the medications such as Ritalin used to treat ADHD effective or detrimental when used to treat the same symptoms in those with ACC?

We hope that our preliminary data will stimulate further research which will more clearly define the relationship between ACC and ADHD.


Boyles, N.S. & Contadino, D. (1997). Parenting a Child with Attention Deficit Hyperactivity Disorder. Los Angeles: Lowell House.

Frances, A., Pincus, H.A., & First, M.B. (Eds.), (1994). Diagnostic and Statistical Manual, 43 rd. Washington, D.C.: American Psychiatric Association.

Lassonde, M. & Jeeves, M.A. (Eds.),   Callosal Agenesis: A Natural Split Brain? (Pp. 235 – 246). New York: Plenum Press.

Ritter, S. (1981). Educational intervention with a primary school girl with agenesis of the corpus callosum. The Exceptional Child, 28, 65 – 72.

Schilmoeller, G.L. & Schilmoeller, K. (2000). Filling a void: Facilitating family support through networking for children with a rare disorder. Family Science Review, 13, 224 – 233.

Sorensen, D.N. (1997). A case study of a child with agenesis of the corpus callosum. American Journal of Speech-Language Pathology, 6, 36 – 44.