The findings are reported in the Canadian Medical Association Journal.
They add to a pattern commonly seen in studies on acupuncture and migraines.. Authors say that raises the question of whether acupuncture works by "non-specific" effects. That is, some people might feel better because they expect to or because of the personal attention from the acupuncturist.
Other experts say the findings do not mean that acupuncture offers nothing more than a "placebo" effect for migraine patients.