Autism and Attention Deficit Hyperactivity Disorder

Prohibiting the diagnosis of ADHD in autism is harmful

Posted Mar 19, 2012



Although the DSM-5 proposed revisions to the diagnosis of autism have precipitated intense controversy about the suggested elimination of the diagnoses of Asperger's Disorder and Pervasive Developmental Disorder, my concern  is about the refusal of the  DSM diagnostic classification committee to permit a diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) in a child diagnosed with autistic disorder. As stated in DSM IV, "Symptoms of overactivity and inattention are frequent in Autistic Disorder, but a diagnosis of Attention-Deficit/Hyperactivity Disorder is not made if Autistic Disorder is present." (p.74, DSM IV, copyright 2000, text revision.) DSM 5 proposes to retain this rule.

ADHD is considered by DSM IV and DSM-5 to be an intrinsic part of Autistic Disorder  not meriting a separate diagnosis. Yet, the symptoms of ADHD are not part of the symptoms listed for DSM critera for autistic disorder. Reading the listed criteria for the diagnosis would not lead a reader to expect to see a child with extreme overactivity and inattention. These symptoms are not formally associated with autism in DSM critera but are a regular feature of the disorder as it is encountered clinically.

The symptoms of ADHD in autistic children should be a treatment target of child psychiatric psychopharmacologists. In my experience, ADHD can be treated with relative ease and safety with a concomitant dramatic improvement in the autistic child's ability to function in school and at home.  The DSM decision to forbid making the diagnosis of ADHD in autistic children often has the unintended consequence of promoting a lack of recognition of symptoms that can be treated to the great benefit of autistic children.

Because ADHD is not a diagnostic label of the autistic child, and ADHD is not always an accepted target of treatment for autistic children, providers pharmacologically treating the ADHD symptoms of a child with autism may have an awkward time justifying this activity to administrators, managed care companies, and parents. One nationally known treatment center would not permit measurement of the clinical severity of ADHD symptoms in the autistic children at the center, and discouraged pharmacological treatment of any present ADHD symptoms, with the explanation that the symptoms were so common that all of the autistic children would be treated for ADHD if pharmacological treatment for this condition were permitted.

Dr. Susan Mayes and colleagues in a series of studies of the co-morbid conditions in autism have developed important data that contribute greatly to a fuller and more clinically rounded picture of autism beyond the DSM core symptoms of difficulty in social communication, difficulties with language development, and repetitive behavior (Research in Autism Spectrum Disorders, Vol 6, Jan. 2012 p. 277-285.) In brief and greatly oversimplified, in a study of over 1000 children, the authors examined 158 children diagnosed with ADHD alone for symptoms of autism and ADHD. There were almost no children diagnosed with ADHD alone who had autistic symptoms. A second part of the study examined 847 children diagnosed with autism for symptoms of autism and ADHD.  All of the autistic children had many symptoms of ADHD. Dr. Mayes's study concluded that ADHD is an intrinsic part of autism as the DSM has insisted.

In a closely related study, Dr. Mayes and colleagues studied 1605 children, 435 of them diagnosed with autism, for symptoms of ADHD and oppositional defiant disorder (Research in Autism Spectrum Disorders, Vol 6, Jan. 2012, pp. 1-10). The remaining children had an array of diagnoses;  186 "typical children" were largely free of any diagnosable psychiatric illness. Oppositional defiant disorder (ODD) is a DSM diagnosis characterized by such symptoms as losing temper, arguing with adults, and refusing to comply with adult requests or rules. ODD is not mentioned as a problem related to autism in DSM IV or DSM-5. 40% of the autistic children in this carefully done study had ODD. Medications for the treatment of ADHD can often be helpful in treating ODD.

The value of recognizing and treating ADHD in children with autism who meet criteria for ADHD is suggested in the following study by Lawrence Scahill, M.S.N., Ph.D. and colleagues in an article in the Journal of Child and Adolescent Psychopharmacology (Vol 16, Number 5, 2006  pp. 589-598). Contrary to the rules of DSM, for purposes of this research study,the diagnosis of ADHD was permitted in autistic children who also met DSM criteria for ADHD. To oversimplify, in this small study, twenty-five children with severe symptoms of ADHD diagnosed with either Pervasive Developmental Disorder or autism were given a  non-stimulant medication for the treatment of ADHD called guanfacine (Tenex). All of the children had ADHD symptoms that had failed to respond to methylphenidate (Ritalin). The average age of the children was nine years and they had an average IQ of 50.  Amongst other measures, the children's hyperactivity was measured on parent ratings and teacher ratings of a scale called the Aberrant Behavior Checklist (ABC). At the end of the eight week study, parents' ratings on the hyperactivity subscale of the ABC declined from 31 to 18 (39% change) a highly significant statistical and clinical improvement. Also, significant improvements were noted on parent ratings on the ABC scales on irritability from 17 to 11 (a 34% change) and on social withdrawal from 12 to 7 (40% change.) Irritability and social withdrawal are not symptoms of ADHD, but it is not uncommon in the successful pharmacological treatment of ADHD to obtain clinical benefits beyond the symptoms of hyperactivity and inattention of ADHD.

The antipsychotic drug risperidone has been approved by the FDA for the treatment of irritability in children with autism. Risperidone has a much wider and more severe set of side effects than medications used to treat ADHD. The possibility of substituting ADHD medications for antipsychotic medications in the treatment of irritability would be an important benefit for patients. Such exchanges cannot readily be made as of this time; in general, antipsychotics seem more effective for aggressive children with ADHD than are medications used for the treatment of ADHD alone.  The possibility of using ADHD medications, however, merits further clinical and research consideration.  Scahill and colleagues note that the improvement in hyperactivity in the children in his study was the same as was found in a sample of aggressive hyperactive autistic children treated with risperidone. 

It is not widely appreciated that many antipsychotics are probably effective in treating ADHD.  Antipsychotics would be difficult to research ethically for the treatment of ADHD because their many side effects make them much more risky than stimulants and other medications for the treatment of ADHD. That antipsychotics may exert their anti-aggressive effect through their decreasing the symptoms of ADHD is a possibility. At the least, treating aggressive, hyperactive, autistic children who have ADHD with agents used to treat ADHD in children without autism may allow for lower doses of antipsychotics to be used to control the aggression in autistic children. The Scahill paper and others on the treatment of ADHD in autistic children seem to offer additional pharmacological treatment possibilities for this population.

The situation may be roughly analogous to children diagnosed with bipolar disorder of whom more than 90% have an additional diagnosis of ADHD. The ADHD diagnosis was given short shrift by many of the believers of the diagnosis of bipolar disorder in children and instead the children were given a variety of relatively risky adult medications used in adult bipolar disorder that were largely ineffective and associated with serious side effects.

Copyright: Stuart L. Kaplan, M.D.

Stuart Kaplan, M.D. is the author of Your Child Does Not Have Bipolar Disorder: How Bad Science and Good Public Relations Created the Diagnosis, available at