This project is a Phase II study involving 100 participants across 8 ALS clinics across Canada. The trial, led by the Principal Investigator of the Canadian Neuromuscular Disease Registry (CNDR) and the Chair of the Canadian ALS Research Network (CALS) will examine whether pimozide, a drug already approved by Health Canada for use in psychoses like schizophrenia and Tourette’s syndrome, might slow progression of ALS. Pimozide is particularly effective at stabilizing neuromuscular function, which means it can strengthen the connection where the motor neuron meets the muscle (called the neuromuscular junction or NMJ). It is hoped that by strengthening this connection, there will be preservation of transmission of signals from the brain to the muscle and slowing of paralysis in ALS. The project also involves the validation of an exciting new potential biomarker. Biomarkers are ways of monitoring the body (eg. looking for something in blood or doing a particular physical examination) to either diagnose ALS earlier, select individuals for a trial or monitor effectiveness of a treatment.