Attention deficit hyperactivity disorder (ADHD), usually diagnosed in children, may show up for the first time in adulthood, suggest two recent studies.
And not only can ADHD appear for the first time after childhood, the symptoms for adult-onset ADHD may be different from symptoms experienced by kids, found the researchers.
“Although the nature of symptoms differs somewhat between children and adults, all age groups show impairments in multiple domains —school, family and friendships for kids, and school, occupation, marriage and driving for adults,” said Dr Stephen Faraone, a researcher at State University of New York Upstate Medical University in New York, and author of an editorial accompanying the studies in JAMA Psychiatry.
Dr Faraone, however, cautions that some newly diagnosed adults might have had undetected ADHD as children. Support from parents and teachers, or high intelligence, for example, might prevent ADHD symptoms from emerging earlier. It is not clear whether study participants “were completely free of psychopathology prior to adulthood”, he said.
One of the studies, from Brazil, tracked more than 5,200 people born in 1993 until they were 18 or 19 years old.
At age 11, 393 kids, or 8.9 per cent, had childhood ADHD. By the end of the study, 492 participants, or 12.2 per cent, met all the criteria for young adult ADHD except the age of diagnosis.
Childhood ADHD was more prevalent among males, while adult ADHD was more prevalent among females, the study also found. Just 60 of the nearly 400 kids with ADHD still had symptoms at the end of the study, and only 60 of the nearly 500 adults with ADHD had been diagnosed as children.
“The main take-home message is that adult patients experiencing significant and lasting symptoms of inattention, hyperactivity or impulsivity that cause impairment should seek evaluation, even if they began recently by their perception, or if family members deny their existence in childhood,” said study author Luis Augusto Rohde, researcher at Federal University of Rio Grande Do Sul.
The second study focused on 2,040 twins born in England and Wales in 1994 and 1995. During childhood, 247 of them met the diagnosis criteria for ADHD. Of those, 54 still met the diagnosis criteria for the disease at age 18.
Among 166 individuals with adult ADHD, roughly one third did not meet the criteria for ADHD at any of four evaluations during childhood.
It is possible some of these adults had undiagnosed ADHD as kids, but symptoms may also look different in older people, said study author Louise Arseneault of King’s College, London.
People with adult ADHD may have inattentive symptoms such as being forgetful, whereas children may have hyperactive symptoms, said Dr Arseneault. “And if adults do experience hyperactive symptoms, these symptoms may manifest more as feelings of internal restlessness rather than obvious hyperactive behaviour like running or climbing around in inappropriate situations,” she said.