Moreover, both the inflammation of microglia in the motor cortex and spinal cord of ALS patients and the expression of IDO and QA in neuronal cells and microglia increased significantly.501,553 In parallel with the impaired de novo pathway, the NAD+ decline in the ALS might also be due to the inadequate NAMPT-mediated NAD+ salvage synthesis pathway. Here, IDO1 is linked to amyotrophic lateral sclerosis.