It works. It is just a matter of learning how to manage your posture so that you don't hurt yourself.
How lovely that your mother knows about the Alexander Technique. I'm sure it does her a world of good. I know well, as I'm a certified teacher of the Technique, have been involved with it for more than 30 years, three of those years in teacher-training school in San Francisco. Do you know which teacher or teachers your mother studied with?