Deep-TMS treatment to the Dorsolateral Prefrontal Cortex in Adults with ADHD

Introduction: ADHD is one of the most prevalent neurodevelopmental disorders among children and adolescents all over the world. The disorder is characterized by symptoms of inattention, hyperactivity and impulsiveness. Pharmacotherapy is the most common treatment for ADHD today, however it is accompanied by many side effects such as headache, trouble sleeping, upset, nervousness, irritability and weight loss. In the past years new techniques of neuro-modulation have been introduced as a sufficient treatment tool for ADHD. One of these techniques is deep TMS (Transcranial Magnetic Stimulation). The cingulo-frontal-parietal (CFP) brain network controls goal-directed processes and provides the ability to respond to changing attentional task demands. Within this network, hypoactivity of the dorsolateral prefrontal cortex (DLPFC) has been observed in patients with ADHD. High-frequency, repetitive dTMS (rTMS) increases cortical excitability that outlasts the period of stimulation. The current study examined the efficiency of rTMS to the DLPFC in adults with ADHD by using fMRI.

Methods: Deep-rTMS was applied to the DLPFC in adults with ADHD in a randomized, double blind treatment protocol that included pre-treatment cognitive training, for 15 treatments over 3 weeks. Subjects were randomized to receive right, left or sham DLPFC stimulation. Clinical effects were assessed with a standard symptoms scale (CAARS) and a cognitive assessment battery (Mindstreams) at 3 time-points: prior to participation (SCR), after the treatment phase (V15) and 1 month post-treatment (V16). Neurophysiological effects were assessed with fMRI using an N-back task with different levels of working memory (WM) demand before and after the treatment phase.

Results: 39 subjects received rTMS; 34 completed the treatment phase and were included in the current analysis. Significant improvements were observed in CAARS inattention sub-scale and in the attention and executive function scores on the Mindstreams battery in the real stimulation groups mainly in the right DLPFC group. In the fMRI, there was a significant increased activation in the right DLPFC during the WM task after 3 weeks of treatment with dTMS.

Conclusions: Results of this ongoing study indicates that dTMS is an efficient tool in modulating attention related brain networks. Using dTMS, a feasible technique, shows great promise in improving attention symptoms for adults with ADHD.