Hasan, Alkomiet; Schneider, Marc; Schneider-Axmann, Thomas; Ruge, Diane; Retz, Wolfgang; Rösler, Michael; Falkai, Peter; Wobrock, Thomas
A Similar but Distinctive Pattern of Impaired Cortical Excitability in First-Episode Schizophrenia and ADHD.
In: Neuropsychobiology, No. 2: pp. 74-83
Background: First-episode schizophrenia (FE-SZ) and attention deficithyperactivity disorder (ADHD) are both neuropsychiatric disordersassociated with an impaired dopaminergic transmission. Though displayingdifferent clinical phenotypes, a common pathophysiological pathway isdiscussed controversially. Several studies using transcranial magneticstimulation (TMS) revealed abnormalities in human motor cortexexcitability in both schizophrenia and ADHD patients. Studies oncortical excitability comparing these two diseases directly are lacking.Method: In this study, a total of 94 subjects were analyzed.Twenty-fiveFE-SZ patients were directly compared with 28 ADHD patients and 41healthy controls (HC). We investigated cortical excitability (inhibitoryand facilitatory networks) with single- and paired-pulse TMS to the leftand right motor cortex. Results: Compared to HC, FE-SZ/ADHD patientsdisplayed an impaired cortical inhibition over the left hemisphere.Apart from an enhanced intracortical facilitation, FE-SZ patients didnot differ compared to ADHD patients in the main outcome measures. Bothpatient groups presented a dysfunctional hemispheric pattern of corticalinhibition and facilitation in comparison with HC. Conclusion: Theresults of this study indicate a pattern of cortical disinhibition andabnormal hemispheric balance of intracortical excitability networks intwo different psychiatric diseases. These effects might be associatedwith an imbalance in GABAergic and dopaminergic transmission and mightprovide evidence for a common pathophysiological pathway of bothdiseases.