Motor cortical plasticity in adolescents with early onset schizophrenia: A TMS-EMG study assessing the perturbation effect of intermittent and continuous theta burst stimulation.

Background: Neuroplasticity in adolescents is distinct from that of adults. Literature pertaining to neuroplasticity in schizophrenia is limited to adult populations. Aim: We aimed to assess baseline (or resting) cortical excitability and cortical plasticity in adolescents with schizophrenia using the transcranial magnetic stimulation-electromyography (TMS-EMG) protocol. Methods: Twenty adolescent cases with schizophrenia and 20 age and gender matched healthy controls were studied using a crossover design. Single pulse TMS elicited resting motor threshold (RMT) and motor evoked potentials (MEPs) were assessed. Cortical plasticity was determined by tracking MEPs after a single session continuous theta burst stimulation (cTBS) and intermittent theta burst stimulation (iTBS) up to 120 min at 12 intervals. Results: Baseline (or resting) cortical excitability was found to be significantly lower in cases compared with controls. Response patterns to cTBS and iTBS were similar between the crossover. While cTBS led to inhibitory response, iTBS had an excitatory effect in both the groups. In the cases, while cTBS led to significantly greater initial inhibitory response, iTBS led to significantly lower excitatory response, compared with controls. The time taken to return to baseline excitability was significantly longer after receiving cTBS for cases, compared with controls. Conclusions: iTBS and cTBS lead to excitatory and inhibitory response, representing classical long-term depression and long-term potentiation effects, respectively, in both cases and controls. We conclude that adolescents with schizophrenia have significantly lower baseline (resting) cortical excitability as well as significantly greater inhibitory plasticity; excitatory plasticity is significantly lower. [ABSTRACT FROM AUTHOR]