Complementary Alternative Cardiovascular Medicine

126 Alternative Cardiovascular Medicine
Physiologic Impact of Meditation (Nonclinical Samples)
Perhaps the most researched area in meditation has been the physiologic
impact of meditative practice. This research represents the earliest
studied aspect of meditative practice, dating back to as early as 1935,
when French cardiologist Theresa Brosse, traveled to India to study the
physiology of meditation (25). Now, more than 50 yr later, there is a
strong body of evidence describing both acute and lasting physiologic
changes that occur as a result of meditation. Nearly exclusively focused
on TM, these studies, as a whole, describe a distinct pattern of physiologic
response. The most significant of these results will be reviewed
below. For ease of discussion, results have been divided into major
physiologic systems or areas. A more complete review of research in this
area has been published by Jevning and colleagues (19).
OXYGEN CONSUMPTION AND RESPIRATION
In the early studies of the impact of meditation on respiration, Wallace
and colleagues reported a marked decrease in O 2 consumption and CO 2
elimination during a 30-min TM practice, with no change in respiratory
quotient (subjects acted as their own controls). A decrease in respiration
rate and minute ventilation was also found (8,26–29). As the availability
of long-term meditators has increased over time, there have been several
more sophisticated studies that have replicated and furthered these findings
(29–32). Some researchers found even more marked decreases in
respiration and also noted several episodes of respiratory suspension
that were linked to a subjective report of an experience of what has been
termed “transcendental consciousness” (30,31). These findings sparked
further study investigations of the other physiologic changes present in
these respiratory suspensions to define and describe this state of “transcendental
consciousness” (31,32). These autonomic and biochemical
findings will be reviewed below. In addition, several studies compared
the respiratory changes found in TM with those found during ordinary
rest or relaxed states. These studies found a significant difference in
mean declines in respiration between TM and rest or relaxation in
nonmeditators (29,30).
ENDOCRINE AND NEUROTRANSMITTER EFFECTS
The overall results of research on the endocrinologic impact of meditation
show acute declines in hormones that are implicated in the stress
response. Cortisol, thyroid-stimulating hormone (TSH), and growth
hormone (GH) all decline during TM practice (33). Several longitudinal
studies confirm that these effects are long lasting in subjects who regularly
practice meditation (33–35). Several other hormones remained