Investigating the effect of transcendental meditation on blood pressure: a systematic review and meta-analysis.

Some evidence from previous randomized controlled trials and systematic reviews has demonstrated a positive association between hypertension and transcendental meditation (TM). However, other trials and reviews showed the effect of TM on blood pressure (BP) was unclear but did not use subgroup analysis to rigorously investigate this relationship. The American Heart Association has stated that TM is potentially beneficial but did not give a standard indication. The present study explored several subgroup analyses in systematic reviews to investigate the effect of TM on BP. Medline, Embase, Cochrane Library, Web of Science and Chinese BioMedical Literature Database were searched through August 2014. Randomized controlled trials of TM as a primary intervention for BP were included. Two reviewers independently used the Cochrane Collaboration's quality assessment tool to assess each study's quality. Twelve studies with 996 participants indicated an approximate reduction of systolic and diastolic BP of -4.26 mm Hg (95% CI=-6.06, -2.23) and -2.33 mm Hg (95% CI=-3.70, -0.97), respectively, in TM groups compared with control groups. Results from subgroup analysis suggested that TM had a greater effect on systolic BP among older participants, those with higher initial BP levels, and women, respectively. In terms of diastolic BP, it appears that TM might be more efficient in a short-term intervention and with individuals experiencing higher BP levels. However, some biases may have influenced the results, primarily a lack of information about study design and methods of BP measurement in primary studies.