Studies Look at ADHD in Adults

A new study, led by a team of British researchers, looked at young adults with ADHD and found that a significant number of these individuals did not exhibit symptoms in childhood as required by the definition of ADHD in the The Diagnostic and Statistical Manual of Mental Disorders, (DSM-V), from the American Psychiatric Association. 

The DSM-V definition of ADHD requires that the individual have:

Six or more persistent symptoms of inattention and/or hyperactivity-impulsivity, several of which were present prior to 12 years of age, that interferes with functioning or development, which are present in two or more settings (eg. at home and at school or at work), and which interfere with social, academic, or occupational functioning.

The researchers looked at a subset of more than 2,000 individuals as part of a study of twins, and found that adults with ADHD included both those who had "childhood onset" ADHD that persisted into adulthood and those who did not meet the DSM requirements for ADHD in childhood but who met them (absent the age of onset) in adulthood. Specifically, they found that, "among 166 individuals with adult ADHD, 112 (67.5%) did not meet criteria for ADHD at any assessment in childhood." 

The British researchers noted differences between the childhood and adult onset groups in areas such as severity of symptoms and comorbid mental health conditions and suggested that more research is needed to determine the relationship between these two types of ADHD and whether they are really the same disorder.

A second study, this one led by Brazilian scientists and published in the same journal as the British study, led researchers to conclude that their findings did " not support the assumption that adulthood ADHD is necessarily a continuation of childhood ADHD. Rather, they suggest the existence of 2 syndromes that have distinct developmental trajectories."

As the British research team noted, "the extent to which childhood-onset and late-onset adult ADHD may reflect different causes has implications for genetic studies and treatment of ADHD."

NIMH Notes Limits of DSM

We recently came across an excellent explanation of the limits of the American Psychiatric Association's DSM, the newly revised Diagnostic and Statistical Manual of Mental Disorders. We have not been fans of the DSM approach to attention difficulties, and have written before about how the DSM does not go far enough in understanding how attention impacts learning and behavior.

The more recent criticism of the DSM was prompted by the release of a complete revision of this Manual, after much consideration, this past May. It comes from Thomas R. Insel, M.D., Director of the National Institute of Mental Health (NIMH), who discussed the limitations of the DSM in a blog post in which he described the DSM as, "at best, a dictionary, creating a set of labels and defining each."

Dr. Insel notes that the DSM diagnoses "are based on a consensus about clusters of clinical symptoms," not on laboratory measures or scientific studies. He goes on to explain that the NIMH has been engaged in a project to move beyond such diagnoses by focusing on research into areas such as imaging, genetics, and cognitive science.

This project, Research Domain Criteria (RDoC), will form the basis of how the NIMH, and presumably the extensive network it influences, looks at diagnosis, moving beyond the limits of the DSM. As the NIMH notes, "Rather than starting with an illness definition and seeking its neurobiological underpinnings, RDoC begins with current understandings of behavior-brain relationships and links them to clinical phenomena." This approach is very much in keeping with the approach we apply at The Yellin Center, and we look forward to the day when this project results in a universal understanding of the need for looking at the science behind labels.