Adult ADHD presents diagnostic and therapeutic challenges

Current evidence suggests that attention-deficit/hyperactivity disorder (ADHD), the most common neurodevelopmental disorder of childhood, often persists throughout life and may affect 4 to 5 percent of U.S. adults. Yet adult ADHD remains controversial — a clinically heterogeneous, multifactorial syndrome with no set of consistent findings to support its diagnosis and no single etiology to explain its pathology. This complexity may make providers reluctant to assess for ADHD, potentially leading to underdiagnosis and undertreatment.

Inattention symptoms predominate

Several studies, including a 2009 study in The Journal of Clinical Psychiatry, have demonstrated that ADHD symptoms in adults differ considerably from those in children. More than 90 percent of adults with ADHD have attention issues, including difficulty with planning, follow-through, organization and time management. Hyperactivity may decline or disappear in adulthood, but impulsivity remains a significant problem. In adults, manifestations can be subtle, including symptoms as diverse as restless, driven activity, an inability to relax or sexual impulsivity.

These important distinctions are not reflected in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). The revised criteria for adult ADHD remain child-focused, and only about one-third of adults meet them. Furthermore, many patients continue to have problems with executive functioning — the neurologically based skills involving mental control and self-regulation — even when the core symptoms outlined in DSM-5 are effectively treated.

For adults, the consequences of lifelong functional difficulties can be devastating, says J. Michael Bostwick, M.D., a psychiatrist at Mayo Clinic's campus in Rochester, Minnesota. "Little people, little problems; big people, big problems," he observes.

Diagnosis is also complicated when behavioral, mood and medical disorders, including depression, anxiety, substance use, thyroid problems and sleep apnea, are present. Medical conditions can mask symptoms of adult ADHD, and psychiatric comorbidities make treatment more difficult. By some estimates, more than half of adults who had childhood ADHD have one or more psychiatric disorders.

Diagnostic criteria

ADHD is a clinical diagnosis, so a detailed history and exam are critical. Adult ADHD should be suspected when:

  • Core symptoms are present but don't meet full ADHD criteria
  • Residual symptoms cause serious functional difficulties
  • Substance use or mood and anxiety disorders combine with core symptoms
  • A long history of psychosocial dysfunction exits, including disrupted education, employment and relationships
  • A discrepancy exists between intelligence and achievement

"When ADHD hasn't been previously diagnosed, it's usually possible to trace behavioral and attentional difficulties back to preschool," Dr. Bostwick says. "When people mature, ADHD manifests as underachievement. Many adult patients are failing in life; they may have a history of work and relationship issues and an inability to function at a level equal to their intelligence. They may recognize that they are as intelligent as their friends but may be painfully aware they have not had the same success."

Challenges of treating adult ADHD

Therapy for adult ADHD can be challenging and is a matter of some debate. As in pediatric ADHD, stimulants are considered a first line treatment, but they tend to be less effective in adults, are associated with a slight cardiovascular risk, and are more likely to be abused or diverted, especially among adolescents and college students. Although medications can improve social and behavioral function, they rarely normalize behavior completely. Even when core symptoms of ADHD are successfully managed, functional improvements may be relatively modest.

In addition to medications, an integrated treatment plan should include identifying a patient's strengths and weaknesses, assessing for residual symptoms, and employing psychosocial interventions such as time management and cognitive behavioral therapy. "We try to tailor medications to a patient's needs and mitigate abuse potential," Dr. Bostwick says. "Then we work very hard to build skills that will bring order to a disordered life."

For more information

Wilens TE, et al. Presenting ADHD symptoms, subtypes and comorbid disorders in clinically referred adults with ADHD. The Journal of Clinical Psychiatry. 2009;70:1557.