In the most recent scientific investigation, run by Michaell Irwin, the Norman Cousins Professor of Psychiatry at the Semel Institute for Neuroscience and Human Behavior at the University of California at Los Angeles, 112 people aged 59-86 were divided into two groups and studied over 25 weeks. One group took tai chi classes three times a week, learning and practicing 20 exercises. The other attended health education classes.
At the end of 16 weeks, all of the participants were given a dose of a shingles vaccine. Shingles is caused by the chicken-pox virus, which remains in people's systems from childhood. As people age, their immune systems weaken, and the virus can express itself in a painful, blistery rash. Shingles, which can be a mild irritation or a major impairment, afflicts as many as one-third of adults over 60.
When the study concluded, the tai chi practitioners had an immunity level double that of the health education group - a level usually associated with middle age. Moreover, their physical condition, vital energy, mental health and pain levels had all improved.