1. Effects of Yoga Versus Walking on
Mood, Anxiety, and Brain GABA
Levels
Presented by: Julia Ho, March 7, 2012

2. Streeter et al. (2010). Effects of Yoga Versus Walking on
Mood, Anxiety, and Brain GABA Levels: A Randomized
Controlled MRS Study., The Journal of Alternative and
Complementary Medicine, 16(11), 1145-1152.

3. Background
 -previous studies of yoga as a therapeutic
intervention for anxiety, epilepsy and depression
 Khalsa, S. Yoga as a therapeutic intervention: A
bibliometric analysis of published research studies.
Indian Journal of Physiology and Pharmacology, 2004.
 Craft, L.L. and Landers, D.M. The effect of exercise on
clinical depression and depression resulting from mental
illness: A meta-analysis. Journal of Sports and Exercise
Psychology, 1998.
 Yardi, N. Yoga for control of epilepsy. Seizure, 2001.

4. Background
 Large body of research on the beneficial effects of
exercise on depression and anxiety
 Craft, L.L., Landers D.M. The effect of exercise on clinical
depression and depression resulting from mental illness:
A meta-analysis. Journal of Sports Exercise
Psychology, 1998.

5. Background
 Medications which increase γ-Aminobutyric acid
(GABA) activity in the brain are used in depression
and anxiety treatment
 Vallium and Librium bind to the same neuroreceptors
which GABA bind to
 GABA is a neurotransmitter in the brain which
functions to inhibit activity in neurons

6. Objectives
 Are changes in mood, anxiety and GABA levels are
specific to yoga or related to physical activity?

7. Methodology
 Subjects recruited from the Boston area community by
newspaper ads, flyers and Internet
 Eligibility: healthy subject with no significant
medical/psychiatric disorders, 18-45 years old
 Exclusionary criteria: any yoga practice in the previous 3
months or a lifetime history of one yoga session/week for
≥4 weeks, current participant in psychotherapy, prayer
groups, or mind-body disciplines, neurological disorders
or medical condition that would compromise subject
safety, treatment within the previous 3 months with meds
that might affect the GABA system, alcohol consumption
> 4 drinks/day and contraindication to magnetic
resonance evaluation

8. Methodology
 Recruitment flow chart

9. Methodology
 Experimental design: clinical trial type study testing
treatment interventions
 Independent variables: Walking intervention, Yoga
intervention
 Iyengar Yoga sessions: 60-min, 3x/wk (equivalent to 3.0
METs)
 Walking sessions: 60-min, 3x/wk, 2.5 miles per hour on a
flat surface (equivalent to 3.0 METs)
 N.B.: METs (metabolic equivalents) are used to rate and
compare the physical demands of various activity by the
American College of Sports Medicine

10. Methodology
 Dependent variable 1: GABA level
 All subject had three magnetic resonance spectroscopy
(MRS) to obtain GABA levels
 Scan 1 at baseline
 Scan 2 after 12-week intervention was followed by 60-min yoga
or walking intervention which was followed by
 Scan 3
 Dependent variable 2: Mood and anxiety scales
 Taken at weeks 0, 4, 8 and 12 and before each MRS
 Mood scale: Exercise Induced Feeling Inventory (EIFI)
 Positive Engagement, Revitalization, Tranquility and Physical
Exhaustion
 Anxiety Scale: State scale of the Spielberger State-Trait
Anxiety Inventory (STAI)

11. Methodology
 Yoga intervention format: Certified Iyengar yoga
instructors taught the yoga interventions which were
monitored for consistency by the researchers
 Walking intervention structure: group sessions
which sessions walked around the gym perimeter
 Between scan 2 and 3, the subjects walked on a treadmill
set to 2.5 mph with 0 incline

12. Demographics and Study Participation

13. Results
 Statistical analysis on:
 A GEE (generalized estimating equation) model for
changes in mood and anxiety scores for each group at
weeks 0, 4, 5 and 12
 Tonic changes in GABA levels: subtracting Scan 1 from
Scan 2 values; acute changes in GABA level: subtracting
Scan 2 from Scan 3 values
 Tonic and Acute changes in GABA levels
 Correlations of mood and anxiety scores with GABA
levels for each scan
 Correlations of tonic and acute changes in mood and
anxiety scores with tonic and acute changes in GABA
levels

14. Results
 Main findings:
 the 19 yoga subjects reported greater improvement in
mood and greater decreases in anxiety than the 15
subjects in the walking group
 There were positive correlations between improved mood
and decreased anxiety and thalamic GABA levels
 The yoga group had positive correlations between
changes in mood scales and changes in GABA levels

15. Discussion
 Limitations of the study:
 Significantly greater level of physical activity level outside
the intervention in the walking group compared to the
yoga group
 The higher level of outside activity in the walking group
could have contributed to the finding of smaller changes
in mood and anxiety in the walking group as the
intervention may not have been great enough physical
challenge given the greater level of outside activity

16. Discussion
 First study to demonstrate that increased thalamic
GABA levels are associated with improved mood
and decreased anxiety
 Effect of yoga intervention on GABA levels may be
due to the ability of yoga practices to increase
parasympathetic nervous activity
 Merits future study of yoga on mood disorders and
other neurotransmitters e.g. norepinephrine and
sertonin

17. Conclusion
 Depression is one of the most common mental
health disorders
 Canadians being diagnosed and treated for
depression: 2.72 million in 1993 to 7.8 million in
2000. Amount spent on antidepressants rose from
$161 million in 1993 to $543 million in 2000.*
 Implications of future research into yoga intervention
in the treatment of depression could lead to
significant cost savings and a more generalized
acceptance of alternative treatments in the
healthcare system
 *Source: IMS Health statistics