Transcranial Magnetic Stimulation-Evoked Cortical Inhibition: A Consistent Marker of Attention-Deficit/Hyperactivity Disorder Scores in Tourette Syndrome

• Published in: Biological psychiatry (1969) 2005-06, Vol.57 (12), p.1597-1600
• Main Authors: Gilbert, Donald L., Sallee, Floyd R., Zhang, Jie, Lipps, Tara D., Wassermann, Eric M.
• Format: Article
• Language: English
• Subjects: ADHD; Adolescent; Adult; Adult and adolescent clinical studies; Attention Deficit Disorder with Hyperactivity - diagnosis; Attention Deficit Disorder with Hyperactivity - physiopathology; Attention Deficit Disorder with Hyperactivity - therapy; Attention deficit disorders. Hyperactivity; Biological and medical sciences; biological marker; Cerebral Cortex - drug effects; Cerebral Cortex - physiopathology; Cerebral Cortex - radiation effects; Child; Child clinical studies; children; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dopamine Antagonists - therapeutic use; Electric Stimulation; Evoked Potentials, Motor - drug effects; Evoked Potentials, Motor - radiation effects; Female; Humans; Male; Medical sciences; Middle Aged; Motor evoked potential; Neural Inhibition - physiology; Neurology; Neuropsychological Tests - statistics & numerical data; Organic mental disorders. Neuropsychology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Regression Analysis; Reproducibility of Results; Severity of Illness Index; Statistics, Nonparametric; Tourette Syndrome - diagnosis; Tourette Syndrome - physiopathology; Tourette Syndrome - therapy; Transcranial Magnetic Stimulation
• ISSN: 0006-3223; 1873-2402
• DOI: 10.1016/j.biopsych.2005.02.022

Prior case-control studies using Transcranial Magnetic Stimulation (TMS) to probe the neural inhibitory circuitry of Attention Deficit Hyperactivity Disorder (ADHD), Tourette Syndrome (TS), and Obsessive Compulsive Disorder (OCD), have yielded conflicting results. Using regression analysis in TS patients with tics, ADHD, and/or OCD symptoms, all ranging from none to severe, we previously found that TMS-evoked short interval intracortical inhibition (SICI) correlated inversely with ADHD scores. We sought to validate this observation. We used regression to estimate the consistency of the association between ADHD symptom scores and TMS-evoked SICI at two separate visits in 28 children and adults with TS. ADHD scores correlated significantly and consistently with SICI, particularly in patients not taking dopamine receptor blockers ( r = .60 and r = .58). Hyperactivity, not inattention, scores accounted for ADHD-related variance in SICI. SICI reliably reflects the severity of hyperactivity in children and adults with TS.