MacLean, Christopher R. K.
Mechanisms relating stress reduction and health: changes in neuroendocrine responses to laboratory stress after four months of Transcendental Meditation

Order No. 9534651

Pharmacological treatments have as yet failed to show clear reduction in the risk of development of coronary heart disease (CHD). As a result, behavioral treatments such as stress reduction programs continue to receive attention as alternative approaches for prevention as well as for treatment of heart disease. Research on the Transcendental Meditation (TM) technique of Maharishi Mahesh Yogi has shown it to be effective in reducing hypertension and also responsible for decreased basal cortisol levels, both acutely with the practice and longitudinally. In this study, the longitudinal effects of TM and a stress education control (SEC) on neuroendocrine responses to acute laboratory stressors were investigated.

The purpose of the present research was to examine in healthy male caucasians (18-32 yrs) the acute effects of laboratory stressors on plasma cortisol, serotonin, catecholamines, thyroid-stimulating hormone (TSH), growth hormone (GH), testosterone and dehydroepiandrosterone (DHAS) during the stress session, and changes in their responses to stress after four months' participation in either stress management approach.

Plasma for cortisol, serotonin and the catecholamines was sampled periodically throughout the one-hour stress session using a continuous blood withdrawal pump, whereas samples of GH, TSH, DHAS and testosterone were sampled for 4 min at the beginning and at the end of the session. The laboratory stress session consisted of mental arithmetic (6 min), a mirror star tracing task (3.5 min), and isometric hand grip (3.5 min), separated by 25 min rest periods. Samples for cortisol, GH, TSH and testosterone were assayed by radioimmunoassay and statistically analyzed by t-test and one-way repeated measures ANOVA.

When compared to the SEC group by ANCOVA, basal cortisol levels and the average cortisol levels across the stress session decreased, while cortisol responsiveness increased, for the TM group after four months' practice. For the TM group, TSH response to stress decreased while GH and testosterone responses increased over the same period. Plasma serotonin baseline, average and response to stress during the session showed a rise for the SEC group and a fall for the TM group over four months of intervention. No differences between the two groups in the changes in catecholamine responses to stress from pre- to posttest were noted, likely due to the small sample size.

These results indicate that practice of the Transcendental Meditation technique is associated with lowered plasma serotonin and cortisol as well as increased cortisol response to acute stress, in addition to changes in the responses of GH, TSH and testosterone to acute stressors. It is suggested that not only the changes in cortisol but also changes in basal level or response of other hormones reflect reduction of, or resistance to, the effects of chronic stress, i.e., changes towards more optimal adaptive mechanisms. (Abstract shortened by UMI.) Source: DAI, 56, no. 06B, (1995): 3074


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