Attention deficit /hyperactivity disorder (ADHD) is a disorder which manifests in childhood but often persists through adulthood. The most prominent symptoms in adults are inattention, emotional instability, disorganized behavior, impulsivity and restlessness, which cause several restrictions in different areas of life. It is suggested that those symptoms can be attributed to a general deficit in inhibitory control. This hypothesis is supported by several studies revealing that patients with ADHD show poor performance completing inhibitory control tasks.

Furthermore, studies showed that a unique administration of atomoxetin (ATX) significantly improves inhibitory control in patients with ADHD as well as in healthy participtants. In contrast to other medication authorized for the treatment of patients with ADHD, does ATX has no risk for potential addiction. Due its indirect mode of action, ATX has a delayed effect occurence taking up to 2 weeks. However, this apects was unconsidered in those studies.

Although we directly often associate failures in cognitive control with disruptions at prefrontal areas of the brain, there exists a specific brain network which is called the default mode network (DMN), which is suggested to be at least partly responsibe for the ADHD symptomatic.

The following study is interested in which way a 2- week intake of ATX affects the DMN and surrounding networks in their connectivity during a inhibitory control task and during rest in patients with ADHD vs controls.

Inclusion Criteria:

• Male Age 18-45 years Diagnosis of ADHD (patients) or no axis I disorder (controls) according the DSM IV No substance abuse/ dependency Understanding of the study information and declaration of agreement Ability to read, understand and speak German No severe medical disorders No risk for suicide

Exclusion Criteria:

• Drug dependence or the a positive drug screening Other Severe physical disorders Current pharmacological therapy because of another psychiatric disorder Risk for seizure or cardiac problems Impaired liver and renal function Significant deviations in regard to clinical chemistry, haematology or EKG Relationship of dependency with the sponsor or the investigator Unable to keep to the study protocol Known Intolerance of the study medication fMRI scanner incompatibility

Data will be uploaded into the data pool of the Deutsches Netzwerk zu psychischen Erkrankungen.