Instruments for diagnosing Attention-Deficit/Hyperactivity Disorder (ADHD) in childhood are well validated and reliable, but psychometric assessment of ADHD in adults remains problematic. To date the Conners Adult ADHD Rating Scales (CAARS) are frequently used in the assessment of ADHD.

The CAARS were translated into German and a series of studies planned to establish psychometric properties of the CAARS-self and -observer rating scales.

To evaluate the German version of the CAARS.

We recruited 847 healthy German subjects and 466 adult ADHD patients to fill out the CAARS-self report and questions on socio-demographic variables. Additionally, 896 CAARS-observer reports were filled out by significant others and clinical experts. Factor analyses were conducted to obtain factor structure and to replicate the structure of the original American-model. Comparisons between patients and controls, and analyses on influences of gender, age, and education level were calculated. Additional analyses established psychometric properties.

Confirmative factor analysis based on the original American-model showed a high model-fit for both the German healthy control and the adult ADHD patient sample. Analyses of normative data showed significant influences of age, gender, and education level on the emerging subscales for the control sample only. Differences on all subscales were highly significant between patients and controls. Test-, test-retest-reliability was very high, and criterion validity could be established with DSM-IV based clinical interviews. Sensitivity and specificity ratings are overall very satisfying.

The German version of the CAARS is a cross-culturally valid instrument for the assessment of adult ADHD.