However, this study is the first to examine the risk factors for depression in very young children with ADHD, and the first to follow children for an extended period of time. Experts have long suspected an ADHD-depression link in childhood, but the research to date has been inconclusive.
“This study adds more data to the notion that early manifestations of hyperactivity and impulsivity…are not necessarily benign,” says Benedetto Vitiello, MD, chief of the research branch dedicated to child and adolescent treatment and prevention at the National Institute of Mental Health, which funded the study.
But the children in the study aren’t necessarily typical of all children with ADHD, says Rafael Klorman, PhD, a professor of psychology at the University of Rochester Medical Center, in New York. It’s relatively uncommon for ADHD to be identified in children as young as 4, he explains, and kids who are diagnosed at that age tend to have more severe symptoms.
“These kids were diagnosed earlier, which means that the researchers have a sample with especially higher severity,” Klorman says. “They may be getting the high end of the spectrum.”
Parents should not “panic and think their children with ADHD are destined for depression or suicide,” Lahey says. However, he adds, if parents are concerned that their child is showing symptoms of ADHD or depression, they should consult a mental health professional and consider family therapy.
More research is needed to identify effective interventions that can lower the chances of depression in high-risk kids with ADHD, Dr. Vitiello says, echoing Lahey and his colleagues.
Early intervention and treatment are important, as the risk of depression and other health problems associated with ADHD can last well into adulthood. Previous studies have estimated that anywhere from 16% to 37% of adults with ADHD have been diagnosed with major depressive disorder or dysthymia, a milder form of depression.
And in another new study, which appears in the Archives of Pediatric & Adolescent Medicine, researchers at New York University report that teenagers with ADHD are about twice as likely to have problems with alcohol and drugs in their 30s than those without the disorder.
However, the risk seems mainly due to the overlap between ADHD and conduct disorder, a related condition that’s characterized by physical aggression and delinquent behavior, such as stealing and vandalism. The teens who did not show signs of conduct disorder did not appear to be at increased risk for substance abuse, the study found.
Both ADHD and conduct disorder may be an early warning sign for alcohol and drug problems, the researchers suggest.
