Long-Interval Intracortical Inhibition and the Cortical Silent Period in Youth.

BACKGROUND: The cortical silent period (CSP) and long-interval intracortical inhibition (LICI) are putative markers of γ-aminobutyric acid receptor type B (GABAB)-mediated inhibitory neurotransmission. We aimed to assess the association between LICI and CSP in youths. METHODS: We analyzed data from three previous studies of youth who underwent CSP and LICI measurements with transcranial magnetic stimulation and electromyography. We assessed CSP and LICI association using Spearman rank correlation tests and multiple linear regression analyses adjusted for demographic and clinical covariates. RESULTS: The sample included 16 healthy participants and 45 participants with depression. The general mean (SD) age was 15.5 (1.7), 14.3 (1.7) for healthy participants, and 15.9 (1.6) years for participants with depression. Measures were nonnormally distributed (Shapiro-Wilk, p < 0.001). CSP and LICI were not correlated at 100-millisecond (ρ = -0.2421, p = 0.06), 150-millisecond (ρ = -0.1612, p = 0.21), or 200-millisecond (ρ = -0.0507, p = 0.70) interstimulus intervals using Spearman rank correlation test. No correlations were found in the multiple regression analysis (p = 0.35). CONCLUSIONS: Although previous studies suggest that cortical silent period and long-interval intracortical inhibition measure GABAB receptor-mediated activity, these biomarkers were not associated in our sample of youths. Future studies should focus on the specific physiologic and pharmacodynamic properties assessed by CSP and LICI in younger populations.

Mental Health Clinical Research Innovations during the COVID-19 Pandemic: The Future Is Now.

The COVID-19 pandemic put an unprecedented strain on clinical research worldwide. As in-person clinical trials came to a screeching halt, we sought new ways to move forward, or as Bob Dylan put it, "start swimmin' or sink like a stone." Telemedicine has long been a part of medicine and clinical research, but fully remote clinical trials were few and far between. In the midst of the pandemic, at the Washington University School of Medicine we successfully conducted a fully remote clinical trial for a potential COVID-19 therapy, demonstrating the feasibility of fully remote or decentralized clinical trials.