This week the US Agency for Healthcare Research and Quality (AHRQ) released a massive meta-analysis on the effectiveness of meditation (variously defined) for a number of healthcare applications.
http://effectivehealthcare.ahrq.gov/...ort-140106.pdf
The conclusion of the study will not surprise those who have studied or practiced meditation for any length of time: meditation is a mixed-bag, in terms of definitions, applications, and outcomes. The generalization that meditation is basically a good thing, is supported by the study. However, the truism that meditation doesn’t help with everything is also clearly reinforced. As the authors state in their brief abstract of the 400+ page paper:
Meditation programs, in particular mindfulness programs, reduce multiple negative dimensions of psychological stress. Stronger study designs are needed to determine the effects of meditation programs in improving the positive dimensions of mental health as well as stress-related behavioral outcomes. (p.viii)
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Our review shows that there is moderate strength of evidence that mindfulness meditation programs are beneficial for reducing pain severity, and there is low to moderate strength of evidence that mindfulness meditation programs may lead to improvement in dimensions of negative affect, including anxiety, depression, and perceived stress/general distress. Otherwise, much of the evidence was insufficient to address the comparisons for most of the questions. There were also too few trials of mantra meditation programs to draw meaningful conclusions. There may be many reasons for this lack of evidence. (p 136)