Right Prefrontal Deep Tms Effects on Attention Symptoms: Behavioral Outcomes and Electrophysiological Correlates

Background:

Despite its high prevalence, the validated treatment for ADHD is chronic administration of psychostimulants, which is associated with side effects and occasionally not tolerated. Deep TMS using specialcoil designs for targeting neural networks linked with neuropsychiatric disorders, may become a viable alternative.

Objective:

Comparison of rTMS treatment using deep, figure-8 and sham coils on ADHD symptoms.

Methods:

In the current randomized, sham-controlled study, adult ADHD patients received 15 dailysessions of high-frequency rTMS directed to the right prefrontal cortex (rPFC), using either deep, figure-8, ora sham coil. ADHD symptoms and cognitive alterations were assessed using the CAARS-INV, self–reportquestionnaires and performance tests. Additionally, the stop signal task (SST) combined with EEGmeasures was used to asses behavioural inhibition and ERPs. EEG responses to an inhibitory protocol ofpaired TMS pulses over the rPFCwere measured before and after treatments. A healthy control group wasevaluated at baseline for comparison.

Results:

Several ADHD symptoms were improved in patients that received dTMS but not standard figure-8or sham treatment (p=0.007, CAARS; p=0.014, SST). Differences between ADHD patients and healthycontrols were demonstrated in ERPs during the SST, and in response to single and paired TMS pulses. Thelower amplitudes of ERPs in patients correlated with ADHD symptoms and behavioural inhibition measures.

Conclusions:

Repeated stimulation of deep areas in the rPFC has therapeutic potential, where rPFCexcitability is impaired in ADHD patients. Ongoing analysis attempts to establish the neurophysiological measures as predictors and biomarkers for effectiveness of dTMS treatment.

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