Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease. Most patients suffer from painful muscle cramps at some point during their disease. Our recent N-of-1 TJ-68 treatment trial for improving muscle cramps in ALS suggested potential efficacy of TJ-68, a traditional Japanese herbal (Kampo) medicine with a long history of use in Japan. TJ-68 is a manufactured botanical preparation of licorice root and peony root. This study also analyzed plasma metabolomic changes to explore metabolites associated with the severity of muscle cramps in ALS and the potential underlying mechanisms of action of the medicine.

Plasma was obtained from the 11 ALS participants at 5-time points (baseline, two placebo phases, and two active treatment phases). Metabolites were analyzed using mass spectrometry. Data analysis used a linear mixed effects model to: 1) identify metabolites related to ALS muscle cramp severity; 2) TJ-68 effects; 3) to predict response to TJ-68.

Significantly higher glutamine/glutamic acid, arginine, and leucine were found in patients with more severe muscle cramps in ALS. TJ-68 treatment increased tryptophan (P = 0.023) and aconitate (P = 0.034), and reduced serotonin (P = 0.041). Acylcarnitines correlated positively with muscle cramp severity (P= 0.044). Lower baseline values of beta-aminoisobutyric acid,  acetylcholine, alpha-aminoadipic acid, glutamine, and alanine were highly predictable for reduced muscle cramps with TJ-68.

Our study identified correlations between metabolite changes and muscle cramp severity in ALS and delineates the changes with TJ-68 treatment. Several metabolites were found to predict response to TJ-68. Uric acid analysis is pending but may be particularly useful as it has already been studied extensively in ALS and is part of standard metabolic panels. Our study affirms that metabolomic technology can easily be utilized in future ALS studies.