Childhood attention deficit hyperactivity disorder frequently persists into adulthood, bringing heightened risks of additional psychiatric issues and nearly five times the risk of suicide, according to a 20-year study that followed children diagnosed with the disorder.
The study, to be published Monday in the journal Pediatrics, is the most extensive to date establishing links between childhood and adult ADHD, and between adult ADHD and other mental health diagnoses.
Only about 38% of those who had ADHD as children made it to age 27 without either continued ADHD symptoms or at least one other psychiatric disorder, according to the study, which was based on a sample of more than 5,000 people born between Jan. 1, 1976, and Dec. 31, 1982.
"The last thing we want to do is frighten parents and children, but we have to stop trivializing ADHD and start taking it seriously," said lead author Dr. William Barbaresi, director of the Developmental Medicine Center at Boston Children's Hospital, who began his work at the Mayo Clinic in Minnesota in 1993.
Other ADHD experts called the report a research milestone that should nudge public policy toward addressing the disorder, once restricted to pediatrics, as a lifelong challenge with high personal and societal costs — including not just suicide and additional mental health disorders, but lower career achievement and higher rates of divorce, automobile accidents and substance abuse.
More than a quarter of the adults who had both ADHD and another mental health issue abused alcohol, while 16% abused other substances, according to the study. Antisocial personality disorder, hypomanic episodes and major depression also ranked high.
Previous studies with limited and less representative samples have suggested similar outcomes. In those studies, estimates of the persistence of ADHD into adulthood have varied from 6% to 66%.
Monday's study landed in the middle of that range, with nearly 29.3% of the pediatric ADHD cases lasting into adulthood. Nearly as large a percentage — 23.7% — experienced ADHD symptoms with one or more other psychiatric disorders.
The study "is a large one and a long one, so it's good data," said Lenard Adler, director of the adult ADHD program at New York University's Langone Medical Center and author of several books on the topic. "This should be a wake-up."
The study began with 5,718 people at the Mayo Clinic, where Barbaresi worked from 1993 to 2009. It relied on the Rochester Epidemiology Project, a cooperative effort among three medical facilities to share medical records of about 95% of the residents of Olmstead County, Minn., who granted permission to share their information with researchers.
All of the children were in the 41 public and private schools in the city. Researchers identified 379 ADHD cases.
In the end, 232 of those with childhood ADHD agreed to follow-up studies. Their mean age was 27.
Prior to 1987, Adler said, adult ADHD was not included in the Diagnostical and Statistical Manual of Mental Disorders, the basis of psychiatric diagnoses.
"It used to be thought that ADHD … miraculously — poof — it disappeared at age 18," said Ronald Kessler, a healthcare policy expert at Harvard Medical School. "It's only been in the last decade that it's become accepted that adult ADHD exists."
Data since then indicate that adult ADHD affects about 4.4% of the adult population, according to the study.
It is not known how many cases of adult ADHD go undiagnosed. The data in the new study suggest that missed diagnoses can have potentially drastic results — even adults whose childhood diagnosis did not last into adulthood had increased rates of psychiatric disorders.
"We need to change perceptions; we need to change systems," said Barbaresi, who said he found it "extraordinarily difficult" to get insurance companies to approve reimbursement when a primary care pediatrician refers a patient for neuropsychological testing.
Usually, insurers require a diagnosis from a psychiatrist. "That's like saying for diabetes, we'll only test you for renal function after you have kidney failure," he said.
The study does not recommend specific policy changes, saying only that the healthcare system and insurance companies "must be prepared to provide appropriate care for adults with ADHD."
But Dr. Lawrence H. Diller, a behavioral developmental pediatrician at UC San Francisco who has been skeptical about overreliance on drug treatment for ADHD, said he worried the study would "put anxiety and fear in the hearts and minds of parents" and lead to more use of medication as the only treatment. He has argued that while ADHD symptoms may persist into adulthood, grown-ups adapt and lead rewarding lives.
"I'm not saying their condition should be ignored," Diller said. "My point would be if you can get your kid to 18 without the kid going to jail or using drugs, the future starts to look better."