Effects of Yoga Versus Walking on Mood, Anxiety, and Brain GABA Levels

Presented by: Julia Ho, March 7, 2012

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.

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.

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.

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

Objectives Are changes in mood, anxiety and GABA levels

are specific to yoga or related to physical activity?

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

Methodology Recruitment flow chart

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

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)

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

Demographics and Study Participation

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

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

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

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

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