Results of this RCT in a general population of college students indicated nonsignificant reductions of −2.0 mm Hg in SBP and −1.2 mm Hg in DBP in the TM group compared to increases of 0.4 mm Hg in SBP and 0.5 mm Hg in DBP in the control group. These BP reductions in the overall sample may have been limited by the relatively low baseline BP levels. However, findings in this sample showed significant improvement in psychological distress and coping ability. Analysis of the hypertension risk subgroup indicated significant reductions of −5.0 mm Hg in SBP and −2.8 mm Hg in DBP in the TM group compared to increases of 1.3 mm Hg in SBP and 1.2 mm Hg in DBP in the control group. Thus, net reductions of −6.3 mm Hg in SBP and −4.0 mm Hg in DBP for the TM group relative to the control group were observed. Decreased psychological distress and increased coping ability were also found for the TM group compared to controls in the high-risk sample. Reductions in BP were significantly correlated with reductions in psychological distress and increased coping.
Recent meta-analyses of RCTs in predominantly prehypertensive and hypertensive subjects showed that practice of the TM program produced an average SBP/DBP reduction of about −5.0/−3.0 mm Hg.12,13
The net reductions −6.3 mm Hg in SBP and −4.0 in DBP for the TM group relative to the control group in the high-risk subgroup in this study are consistent with previous findings in high-BP samples. Based upon a risk prediction scoring formula for the onset of hypertension from Framingham study data, the net reductions in BP for the TM group are associated with a 52% lower risk for onset of hypertension over a 4-year period.20
Regression analyses further showed that the changes in SBP and DBP were significantly correlated with changes in psychological distress, including anxiety and depression, and coping ability. These findings are congruent with a biobehavioral model of high BP.36
According to this model, psychological distress leads to hyperactivation of the sympathetic nervous system and hypothalamic–pituitary–adrenocortical axis.37
This, in turn, leads to acute and chronic elevations in BP. Thus the reductions in psychological distress factors may have contributed to lower BP. Reductions in sympathetic nervous system and hypothalamic–pituitary–adrenocortical activation with TM practice reported in previous studies suggest central nervous system and neuroendocrine pathways for the effects of the psychological distress changes on BP observed in the current trial.38
Another element in this model is the buffering effect of coping mechanisms. According to the biobehavioral stress model, external stressors (such as financial concerns and work/school stress) induce negative affect (in the form of anxiety, depression, and anger), which in turn adversely impact BP.5,36,39,40
The influence of external stressors on negative affect and BP may be moderated by positive coping mechanisms (employed by constructive thinkers). Previous research has shown that high global constructive thinkers appraise external stressors as less threatening and produce less negative affective and cognitive responses to laboratory stressors, with lower levels of physiological arousal.26
In the present study, coping ability correlated with BP and psychological distress factors. Thus improved coping ability may have contributed to lower BP via its effects on moderating/reducing psychological distress factors.
Study strengths and limitations
There were several important methodological strengths, including the use of random assignment, the use of assessors masked to treatment condition to reduce demand characteristics, and a sizable racially diverse subject sample, which lends confidence in the generalizability of the findings to the college student population.
A limitation is that about 30% of the pretest sample was unavailable for post-testing. This concern is mitigated by the fact that across groups completers did not differ from non-completers on any baseline entry characteristics. Also there were no differences between groups on baseline primary and secondary outcomes in noncompleters.
It is unlikely that baseline differences between the treatment arms in the high-risk subsample could have contributed to the observed BP reduction. ANCOVA results for BP were very similar, regardless of whether baseline coping ability, which was significantly different between groups, was included as a covariate. Differences on other baseline variables were relatively small (~0.1 s.d. on BP and 0.2 s.d. on total psychological distress) and are therefore unlikely to have affected the results substantially.
Future randomized trials of the TM program in college students should evaluate longer-term intervention periods to assess long-term effects on BP and psychological distress.
In conclusion, this is the first RCT to demonstrate that a selected mind–body intervention, the TM program, significantly decreased BP in association with improved psychological distress and coping ability in young adults at risk for hypertension. In addition, there were improvements in mental health in the general student sample and trends toward reduction of BP. Practice of this mind–body intervention may be an effective method to reduce psychological distress, BP, and the risk for prospective development of hypertension in high-risk young adults.