Multiple Sclerosis (MS) and Amyotrophic Lateral Sclerosis (ALS) are neurological diseases whose symptoms are described. Evidence is presented for involvement of harmful reactive oxygen species (ROS) and oxidative stress (OS) with beneficial effects by antioxidants (AO). Details of action mode for AOs and ROS-OS are presented. Mechanistic similarity exists with other brain illnesses, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and Schizophrenia (SCZ). Other factors are involved in a multifaceted manner.