Systematic Review and Meta-Analysis of Transcendental Meditation for Post-Traumatic Stress Disorder

Abstract

Background and Objectives. Our recent systematic review and meta-analysis of all studies on meditation as treatment for PTSD (61 studies) found a moderate effect size of Hedges's g = -0.67 for post-minus-pre change in symptom scores. Separate tests of the four meditation categories found a large effect size of g = -1.13 for the Transcendental Meditation (TM) technique that is significantly greater than for each other category. The present follow-up used a different method, calculating effects relative to internal controls, to better characterize the effects of this meditation technique. Materials and Methods. Our study followed Prisma guidelines. Major databases, research anthologies, and bibliographies were searched for studies that used TM for treating PTSD, all military and civilian populations, and all age groups. Results. The searches located 15 controlled trials on TM that met the inclusion criteria (longitudinal and reporting sufficient statistics to calculate effect sizes), 1248 subjects total, mean age 40.5 years (range 20.6 to 54.4 years), and 46.9% males (range 0% to 100%). Using the random effects model, the pooled effect across all studies of TM compared to other treatments was g = -1.01, 95% CI = -1.29 to -0.74, p < 0.000000001. One-study removed analysis found that no study reduced the pooled effect to less than -1.0. Funnel plots indicated no risk of bias. TM was non-inferior to prolonged exposure therapy, p = 0.0001, and it worked significantly faster (p = 0.04 at week six). Conclusions. TM produced clinically meaningful reductions in PTSD for civilian and military personnel, young and older adults, and for both men and women. We recommend phase-III multisite studies comparing TM with known first-line treatments for PTSD.

Keywords: PTSD; Transcendental Meditation; facilitated support groups; meditation; prolonged exposure therapy; stress reduction.

Figure 3

Results of controlled trials using the Transcendental Meditation technique for treating PTSD in: Male Prison Inmates, Nidich et al., 2016 [45]; Female Prison Inmates, Nidich et al., 2017 [46]; Ukrainian War Refugees, Didukh and Freytag, 2024 [47]; and Congo War Refugees, Rees et al., 2013 [25]. Abbreviations: TM = Transcendental Meditation, TAU = treatment as usual, WLC = waitlist control.

Figure 4

Five studies using repeated measures: Military personnel, South African college students battered women, clinical nurses during COVID, and Congo war refugees. The studies were Nidich et al., 2018 [28], Bandy et al., 2019 [24], Bonamer et al., 2024 [26], Leach and Lorenzon, 2023 [27], and Rees et al., 2013 [25].

Figure 1

Results of the four controlled trials using the Transcendental Meditation technique for treating PTSD in U.S. military personnel: Brooks and Scarano, 1985 [32]; Heffner et al., 2014 [13]; Nidich et al., 2018 [28]; Bellehsen et al., 2021 [33]. Abbreviations: PT = psychotherapy. AMM = adapted mantra meditation. PE = prolonged exposure. HE = health education. TAU = treatment as usual. In Bellehsen, the change was in the CAPS-5 score.

Figure 2

Results of controlled trials using the Transcendental Meditation technique for treating in Earthquake-Tsunami Victims, Yoshimura et al., 2015 [38]; College Students in South Africa, Bandy, et al., 2019 [24]; Clinical Nurses, Bonamer et al., 2024 [26]; and Female Survivors of IPV. Leach and Lorenzon, 2023 [27]. Abbreviations: TMS = TM group in Sendai. TMI = TM group in Ishinomaki. NT = No Treatment. WLC = wait list controls. Group Support = 12 h of facilitated group support, comprising 8 × 1.5-h weekly group sessions delivered over 8 weeks, plus a 1.5-h follow-up session at week 16. As with the four studies on military personnel, these four civilian studies found that treatment with TM produced clinically significant reductions in PTSD symptoms that were greater than those in the control groups.

Figure 5

The Forest plot of the effects of 14 independent studies is arranged from the largest to the smallest effect. These studies are Bandy et al., 2019 [24], Didukh and Freytag, 2023 [47], Yoshimura et al., 2015 [38], Brooks and Scarano, 1985 [32], Bonamer et al., 2024 [26], Nidich et al., 2017 [46], Bellehsen et al., 2021 [33], Heffner et al., 2014 [13], Nidich et al., 2016 [45], Nidich et al., 2018 [28], Leach and Lorenson, 2023 [27]. The fifteenth study, Rees et al., 2013 [25], was excluded from this analysis because it was an outlier that would distort to the analysis. The statistics table shows the effect size, Hedges’s g, the lower and upper limit of the 95% CI, the Z-value, and the p-value for each study. The areas of the black boxes indicate effect sizes. Their size is inversely proportional to the variances of the study. The red diamond at the bottom indicates the pooled effects of all 14 studies. The center of the diamond marks the mean of all groups (−1.012 g) and its width is the 95% CI (−1.288 to −0.736) Effects less than zero favor TM. Effects greater than zero favor controls. Note that the outlier study (Rees, et al., 2013) [25] is not included in this forest plot because it was out of scale. The control groups are NT = no treatment, WLC = wait list control, PT = psychotherapy, TAU = treatment as usual, AMM = adapted mantra meditation, PCT = patient centered therapy, HE = Health Education for PTSD patients, Group Support = facilitated group support with a social worker, PE = and Prolonged Exposure Therapy.

Figure 6

Scatter diagram of Clear Scores, Research Quality. Each circle represents a study. The bold solid line is the linear regression line. The two light lines above and below the linear regression indicate the 95% confidence interval.

Figure 7

Scatter diagram of RCT vs. CT Each circle represents a study. The bold solid lines are the means of the two groups. The two light lines above and below the means are the 95% confidence intervals.

Figure 8

Scatter diagram of Within-Group Effect Size of Controls. Each circle represents a study. The bold solid line is the linear regression line. The two light lines above and below the linear regression indicate the 95% confidence interval.

Figure 9

Scatter diagram of Active vs. Passive Controls. Each circle represents a study. The bold solid lines are the means of the two groups. The two light lines above and below the means are the 95% confidence intervals.

Figure 10

Scatter diagram of Age. Each circle represents a study. The bold solid line is the linear regression line. The two light lines above and below the linear regression indicate the 95% confidence interval.

Figure 11

Scatter diagram of Military vs. Civilian. Each circle represents a study. The bold solid lines are the means of the two groups. The two light lines above and below the means are the 95% confidence intervals.