Teens with bipolar disorder are at increased risk of substance use disorder as they get older, a study by researchers at Massachusetts General Hospital has found. Of the 105 young people with bipolar disorder in the study, 34 percent also had a substance use disorder. Of the 98 teens without bipolar disorder, only 4 percent had a substance use disorder, HealthDay reports. After five years, researchers followed up with 68 of the bipolar patients and 81 of those without the disorder. Almost half of those with bipolar disorder also had a substance use disorder, compared with 26 percent of those without bipolar disorder. The findings are published in the Journal of Clinical Psychiatry .