The research included 105 young people with bipolar disorder and 98 without the illness (the 'control' group). Their average age was 14 when they first enrolled in the study. Bipolar disorder causes unusual shifts in mood, energy and activity levels, and also affects the ability to carry out everyday tasks, according to UPI.
Initially, 34 percent of the young teens with bipolar disorder also had substance use disorder, which means they had a problem with drug abuse. Only four percent of the kids in the control group abused drugs, the study showed.
In addition, the researchers found, almost one-quarter of kids with bipolar disorder smoked cigarettes, compared to just four percent of the comparison group.
Five years after the initial study, the investigators followed up with 68 of the original bipolar patients and 81 members of the control group. Among these participants, almost half of those with bipolar disorder had substance use disorder. Only 26 percent of those without the mental health disorder had trouble with drugs, the study revealed.
The risk was particularly high for people with persistent bipolar symptoms, the study authors said.
Dr. Timothy Wilens was the study's lead researcher. He's chief of child and adolescent psychiatry at MassGeneral Hospital for Children in Boston. He explained that bipolar disorder symptoms usually show up before kids start using drugs or cigarettes.
That means health-care professionals who treat children with bipolar disorder should also look for signs of substance abuse or cigarette smoking, Wilens said in a hospital news release.
The study also looked at the combination of bipolar disorder and conduct disorder. Conduct disorder is a condition characterized by defiant, impulsive and possibly criminal behavior, according to the US National Library of Medicine. When the two disorders were combined, the risk of smoking and drug abuse was even greater, the study found.
Attention-deficit/hyperactivity disorder (ADHD), however, didn't seem to have an impact on the risk of drug abuse in people with bipolar disorder.
"We were surprised to find that conduct disorder, but not ADHD, played such a large role in [increasing the risk] of substance use disorder," Wilens said.
He said it's possible that conduct disorder is at the root of the drug use as teens with bipolar disorder become young adults.