Modulation of Cortical Inhibition by Lovastatin in Neurofibromatosis Type 1: A Randomized, Triple-Blind, Placebo-Controlled Clinical Trial

Neurofibromatosis type 1 (NF1) is associated with GABAergic dysfunction which has been suggested as the underlying cause of cognitive impairments. Previous intervention trials investigated the statins’ effects using cognitive outcome measures. However, available outcome measures have led to inconclusive results and there is a need to identify other options. Here, we aimed at investigating alternative outcome measures in a feasibility trial targeting cortical inhibition mechanisms known to be altered in NF1. We explored the neurochemical and physiological changes elicited by lovastatin, with magnetic resonance spectroscopy and transcranial magnetic stimulation (TMS). Fifteen NF1 adults participated in this randomized, triple-blind, placebo-controlled crossover trial (Clinicaltrials.gov NCT03826940) composed by one baseline and two reassessment visits after lovastatin/placebo intake (60mg/day, 3-days). Motor cortex GABA+ and Glx concentrations were measured using HERMES and PRESS sequences, respectively. Cortical inhibition was investigated by paired-pulse, input-output curve and cortical silent period (CSP) TMS protocols. CSP ratios were significantly increased by lovastatin (relative: p=0.027; absolute: p=0.034) but not by placebo. CSP durations showed a negative correlation with LICI 50ms amplitude ratio. Lovastatin was able to modulate cortical inhibition in NF1, as assessed by TMS CSP ratios, highlighting the potential of this outcome measure to be considered in future large-scale studies.