FMRI activation patterns in adult patients with Attention-deficit Hyperactivity disorder (ADHD)

With a prevalence of 3 to 5% ADHD is the most common disorder of child and adolescent psychiatry. The clinical signs are attention deficits, impulsiveness and hyperactivity and start at the age of 6. ADHD persists in about 20–30% into adulthood. This disorder has a strong genetical link. The rates of concordance (0.7–0.9) in twin studies give strong evidence for this hypothesis. Different candidate genes have been found in molecular genetic association studies and genome studies that differentially modulate monoaminergic transmitter systems (Retz et al. 2002, 2003, 2004; Ogdie et al. 2003). Based on empirical data, methylphenidate is supposed to positively influence the imbalance of dopaminergic and noradrenergic transmission in different brain regions (Volkow et al. 1998). Focus points of interests for investigations are especially the frontal brain regions and the striatum as well as the brainstem/cerebellar regions. In this study, adult patients with ADHD according to the ICD-10 criteria were investigated by functional magnetic resonance tomography. Using an event-related design a continuous performance test with a Go/NoGo-paradigm was used. Thus motor executive function and inhibitory mechanisms could be analyzed. Patients (n=19) and controls (n=17) did not significantly differ in age or gender distribution. Correlation analysis of fMRI activation data with the ADHD self-rating subscores for the attention category showed a diminution of activation at both sides of the gyrus frontalis sup., right gyrus frontalis med., both sides of the nucleus caudatus, left lobulus parietalis sup. and right side of lob. par. inf. as well as at the left gyr. supramarginalis the higher the pathological scores were (condition: „NoGo“: motor inhibition; SPM 99). These data support the hypothesis that in ADHD there are distinct regions with less activity compared to controls in the striatum as well as frontal and parietal lobes. These brain regions are known to be involved in motor execution, planning and attention.