Mindfulness-based cognitive therapy (MBCT), a class-based program for preventing relapse of major depression, shows additive benefit to usual care for patients with three or more previous depressive episodes, according to evidence from two randomized clinical trials. However, because control groups did not isolate MBCT-specific effects, the findings cannot be attributed to the therapy itself. A systematic review of four relevant studies identified methodological weaknesses, highlighting the need for further research to determine whether MBCT has specific effects beyond general care.
A systematic review of randomized clinical trials testing Transcendental Meditation (TM) for cumulative effects on blood pressure found that all five evaluable trials had important methodological weaknesses and were potentially biased by authors' affiliation with the TM organization. Only one trial established adequate baseline blood pressure, only one included follow-up, and only one tested TM in hypertensive individuals. Three trials reported statistically significant differences favoring TM, while two found no significant differences. The review concludes there is insufficient good-quality evidence to determine whether TM has a cumulative positive effect on blood pressure.