The author herself has PD. She tells in the book that yoga has made a huge difference. An excerpt is given below
Yoga has made an enormousdifference. Physically, it helps me to build strength, stability, balance, and limberness. Emotionally, it calms me. And intellectually, it stimulates me, boosting my creativity. “Yoga builds confidence,” as Dr. Becky Farley, a neuroscientist and researcher at the University of Arizona, once told me. “When people embrace yoga, they become more relaxed and able to control tremors, become more balanced and generally feel better about themselves.”