Born in Western Australia, Alan J. McComas received his medical and neurological training in Newcastle upon Tyne (UK), with postdoctoral studies at University College London and the National Hospital for Nervous Diseases, Queen Square, London. He was later appointed Head of Neurology and then of Biomedical Sciences at McMaster University, Canada. Initially specializing in neuromuscular disorders, McComas is best known for having pioneered a method for estimating numbers of motor nerve cells (motoneurons) in the spinal cords and brain stems of living human subjects. Later interests included reflex mechanisms and muscle fatigue, and he (with colleague Adrian Upton) pioneered the use of transcranial magnetic stimulation for the treatment of migraine. As a medical historian, McComas wrote the award-winning Galvani's Spark. The Story of the Nerve Impulse.
He is now Emeritus Professor of Medicine (Neurology) at McMaster University.