A recent follow-up study published in the Journal of Child Psychology and Psychiatry contacted adults who began treatment for “attention-deficit/hyperactive disorder” (ADHD) as children to examine the long-term effects of stimulant drug treatment. Findings suggest that treatment not only fails to reduce the severity of “ADHD” symptoms in adulthood but is associated with decreased height.
“The significant height suppression effect described here adds to the controversy about a possible growth-related cost of long-term use of medication.”
Beginning in 1994, just before the release of the Diagnostic and Statistical Manual, fourth edition (DSM-IV), a research study examined the impact of different treatment modalities on children diagnosed with ADHD. The results of this 14-month study proposed that drug interventions, featuring stimulants commonly known by names such as Ritalin, Adderall, or Focalin, were associated with reduced symptom severity alongside relatively fewer negative side effects. Results following this randomized control trial (RCT), and longer-term follow-up studies of medication into adolescence, were reported and presented in over 100 publications. However, subsequent studies observing these same children 2, 3, and 8 years later found that the impact of medication on alleviating symptoms dissipated after the 14-month treatment phase. Yet, the stunting of their growth, a negative side effect associated with the medication, seemed to persist.
In addition to the concerning findings garnered in follow-up studies, ADHD as a diagnosis has been met with significant controversy from experts in the field commenting on the ADHD diagnostic criteria expansion and its role in ADHD-related overdiagnosis, overmedication, addiction, and drug abuse (see MIA report).
Researchers followed up on this original study, known as the Multimodal Treatment Study of Children with ADHD (MTA), to observe the impact of the extended use of ADHD medication into adulthood. Swanson and co-investigators asked the following questions:
- Do symptoms persist into adulthood?
- Is there a significant long-term symptom-related benefit (e.g. reduced symptom severity) of extended use of medication compared to no use?
- Does continuous use of medication result in greater benefit than interrupted use?
To answer these questions, researchers contacted 515 adult participants from the RCT phase, and assessed the long-term effects of either “consistent,” “inconsistent,” or “negligible” adherence to stimulant medication treatment. Symptoms of ADHD were measured using the DSM-IV diagnosis along with participant height.
Results of this study indicate that high levels of ADHD symptom severity persist into adulthood, that symptom severity was not significantly ameliorated by taking stimulants, and that stimulants were instead associated with height suppression in adulthood.
As an observational study, this data is limited by the measures used, and cannot be interpreted to demonstrate causality. Symptom severity was the primary outcome being observed, which may have been impacted by limits to collecting data on prior medication use. Participant growth may also be related to the timing of treatment and other underlying biological processes.
Observations presented in these studies have yet to be fully incorporated by leading organizations, such as the American Academy of Pediatrics, who the authors write have recently published guidelines to “recommend expanding the diagnosis and treatment of ADHD and using stimulant medication as a first-line treatment for adolescents as well as school-aged children.”
The failure to acknowledge the potential risks involved in medicating ADHD may increase growth-related costs without evidence of beneficial symptom reduction to justify such drawbacks. The authors close by providing implications for revising guidelines and highlight another recent study showing “that initiating treatment with low-intensity psychosocial treatment before adding medication reduced the daily dose on school days by 25% without a reduction in efficacy.” They continue:
“The findings of the MTA suggest that these strategies –which appear to achieve full short-term symptom-related benefits in childhood—may reduce long-term growth-related costs in adulthood.”
James M. Swanson et al, Young adult outcomes in the follow-up of the multimodal treatment study of attention-deficit/hyperactivity disorder: symptom persistence, source discrepancy, and height suppression, Journal of Child Psychology and Psychiatry (2017). DOI: 10.1111/jcpp.12684 (Abstract)