Researchers suggest that symptoms of ADHD that arise in adulthood may be explained by other factors.
Attention deficit hyperactivity disorder (ADHD) is a brain condition characterized by impulsive behavior, hyperactivity, and problems with concentration.
Symptoms of the condition include fidgeting, being easily distracted, forgetfulness, and having poor organizational skills.
Onset of ADHD is most common in childhood; around 11 percent of children aged 4–17 years in the United States have ever been diagnosed with the condition.
Around two thirds of children with ADHD will continue to have the disorder into adulthood, and it is not uncommon for an ADHD diagnosis to be made in adulthood. According to the Attention Deficit Disorder Association, around 5 percent of adults in the U.S. have ADHD.
The new study, however, suggests that the vast majority of people who are diagnosed with ADHD in later life may not actually have the condition, raising questions about whether or not onset of the condition occurs in adulthood at all.
The research was conducted by Margaret H. Sibley, of the Herbert Wertheim College of Medicine at Florida International University in Miami, and her colleagues.
Adult-onset ADHD explained by other factors
The researchers came to their findings by conducting a longitudinal analysis of 239 individuals, all of whom were free of childhood ADHD.
Each of the subjects was assessed every 2 years between the ages of 10 and 25. For the biennial assessments, the team looked at the emergence of ADHD symptoms as well as evidence of substance abuse, cognitive impairments, and mental health disorders.
All information was gathered from self-reports and reports from parents and teachers.
The analysis revealed that for over 80 percent of participants who began to display ADHD symptoms in adulthood, their symptoms could be explained by other factors.
"We found a number of people who looked like they had adult-onset ADHD," explains Sibley, "but when we looked closely, adult-onset symptoms were traced back to childhood or were better explained by other problems, like the cognitive effects of heavy marijuana use, psychological trauma, or depressive symptoms that affect concentration."
What is more, the researchers found that in the absence of a history of psychiatric disorders, "there was no evidence for adult-onset ADHD."
Based on their findings, Sibley and her colleagues suggest that clinicians should be cautious when assessing adults for ADHD, as there are many other factors that could explain the onset of ADHD-like symptoms. The researchers conclude:
"False positive late-onset ADHD cases are common without careful assessment. Clinicians should carefully assess impairment, psychiatric history, and substance use before treating potential late-onset cases."