Psychiatric problems associated with subthreshold ADHD and disruptive behaviour diagnoses in teenagers.

Aim: To study the coexistence of subthreshold diagnoses of both attention deficit hyperactivity disorder (ADHD) and disruptive behaviour disorders (DBD) with other symptoms of child and adolescent psychiatric disorders as well as risk behaviours associated with smoking, alcohol and drug use.

Methods: A population-based sample of twins including 177 girls and 135 boys was interviewed using the Swedish version of Kiddie-SADS Present and Lifetime Version (K-SADS-PL). Subthreshold diagnoses were compiled based on the ADHD and DBD criteria, where each criterion was assessed as 'possible' or 'certain' according to K-SADS-PL. The odds ratios (OR) between the subthreshold diagnoses and each of the screening questions in K-SADS-PL were calculated.

Results: Subthreshold diagnoses of ADHD and DBD coexisted with the screening questions concerning depression, mania, panic attack, phobias, anorexia nervosa, motor tics and posttraumatic stress disorder (PTSD) in girls. In boys, these subthreshold diagnoses coexisted with symptoms of depression and PTSD. For both boys and girls, smoking and high alcohol consumption contributed to a high OR with regard to ADHD and DBD.

Conclusion: Subthreshold diagnoses of ADHD and DBD were risk factors for several other psychiatric symptoms as well as smoking and high alcohol consumption. Thus, a broad clinical assessment is needed for adolescents with such preliminary diagnoses.