More than half of major clinical trials testing treatments for adult ADHD have not adequately tested whether participants actually have ADHD, raising serious concerns about the reliability of the evidence supporting current treatments. This new research european psychiatry.
Attention-deficit/hyperactivity disorder (ADHD) was originally described as a childhood condition defined by observable behaviors that parents and teachers could report, such as excessive running, difficulty sitting still, or constant interruptions. However, in recent decades, ADHD diagnoses in adults have skyrocketed. This proliferation has raised concerns among researchers and clinicians about whether diagnostic criteria originally designed for children are still fit for purpose when applied to adults.
This challenge is important. To receive a diagnosis, adults must reflect on and self-report their own internal experiences (such as feeling distracted or restless) and recall childhood behaviors that occurred decades ago. Many symptoms of ADHD in adults can also be caused by depression, trauma, anxiety, and other mental health conditions. Misdiagnosis can easily occur if these alternatives are not carefully excluded through a thorough differential psychiatric evaluation.
A research team led by Igor Studart systematically reviewed 292 randomized controlled trials (RCTs) in adult patients diagnosed with ADHD. RCTs are widely considered the “gold standard” of clinical research used to determine whether a treatment is effective. Researchers looked at how ADHD was diagnosed in each trial, who conducted the assessment, whether psychiatric comorbidities were included, and whether general mental health was assessed to rule out mimic symptoms.
The results were amazing. Overall, there was wide variation in the diagnostic methods used across trials. Approximately half of the studies (49.7%) diagnosed ADHD without formal evaluation of broader general psychopathology. This means the researchers had no systematic way to rule out the possibility that the participants’ difficulties with attention or hyperactivity were actually symptoms of depression, schizophrenia spectrum disorder, substance use, or another condition.
In 65% of studies, it was unclear who performed the diagnostic assessment or the assessment was not performed by a psychiatrist or psychologist. Instead, many trials relied on “trained raters,” self-rating scales, or computer-assisted evaluations, methods that increase the risk of diagnostic errors.
Additionally, more than half of the studies (53.8%) included participants with other psychiatric comorbidities. This is very problematic because clinical guidelines state that ADHD should not be diagnosed if the symptoms are better explained by another condition. Although more than 87% of studies claimed to adhere to this diagnostic hierarchy (which prioritizes excluding organic or severe mental disorders first), reviewers noted that it was virtually impossible for most researchers to verify this, as it omitted the general mental health assessment required for verification.
The authors concluded that these findings represent “an alarming shift in the common understanding of how psychiatric diagnoses should be assigned in research studies.”
He added: “Unless clinicians and researchers can rely on the fundamental fact that the patients who are the subject of scientific research are diagnostically similar to the patients with whom they are exposed, scientific research risks losing its clinical relevance.”
An important limitation of this review is that it searches only one database (PubMed) and focuses only on the diagnostic methods of the trials, rather than analyzing the actual results. Furthermore, many RCTs did not adequately describe diagnostic procedures, and categorizing these approaches required a degree of subjective judgment by reviewers.
The study, “Diagnosis of ADHD in Adults in Randomized Controlled Studies: A Scoping Review,” was authored by Igor Studart, Mads Gram Henriksen, and Julie Nordgaard.
