Yoga may bring long-term benefits for people with depression

"Yoga can ease depression symptoms, according to the largest study to ever investigate the link," the Mail Online reports.

The study didn't find any benefits from doing yoga at the end of the 10-week study period, but there were improvements in symptoms at a six-month follow-up review. Because of the mixed results, these findings need to be interpreted with caution.

The US study included 122 adults with moderate depression who hadn't responded effectively to antidepressants. They were assigned to 10 weeks of either yoga or health education classes.

The main outcome of interest to the researchers were changes in the participants' symptoms of depression, as measured by depression scores, at 10 weeks.

The researchers didn't find any difference between the groups at 10 weeks. But they did find a difference in terms of symptom improvements between the two groups when they compared the scores from 10 weeks with those after six months.

On their own, the results of this study don't provide firm evidence that yoga is beneficial for depression.

There was no effect on the main outcome the study set out to examine, and participants had responded to advertisements, so likely had an interest in yoga to start with. 

This could mean that they were more likely to be receptive to the idea yoga could have a benefit, so there could have been a placebo effect at work.

These findings don't change current guidelines on the treatment of depression using psychological interventions like cognitive behavioural therapy, as well as antidepressants. 

There is, however, evidence that exercise and practising mindfulness  – the two key tenets of yoga – may help enhance mental wellbeing. 

Where did the story come from?

The study was carried out by researchers from Brown University, the University of California, and the Eyes of the World Yoga Center, all in the US.

It was funded by the US National Institute of Nursing Research and published in the peer-reviewed journal, Psychological Medicine.

The Mail's coverage is generally accurate, but doesn't discuss the study's limitations in any detail.

What kind of research was this?

This randomised controlled trial aimed to see whether yoga is an effective additional treatment for people with depression still experiencing symptoms, despite taking antidepressants.

The researchers report around a third of people don't have an adequate response to treatment with antidepressants, and there's a need for interventions to improve symptoms for people in this situation.

A previous systematic review found people who practise yoga experience more improvement in their symptoms than those who receive usual care.

Hatha yoga, which combines mindfulness along with physical exercise, is the most common type of yoga and the form of yoga assessed in this study.

What did the research involve?

Adults from Rhode Island were recruited to the trial through advertisements.

Eligible participants had to have moderately severe depression, as scored by the well-validated Quick Inventory of Depression Symptomatology (QIDS) scoring system. A score of between 8 and 17 is seen as corresponding to moderately severe depression.

They also had to have no history or symptoms of other mental health disorders, no alcohol use problems, minimal previous experience of yoga, and have been taking a stable antidepressant dose for at least eight weeks.  

Participants were then randomised to either weekly yoga classes (63 people) or health education classes (59) for 10 weeks.

Hatha yoga classes included breathing exercises, meditation, postures, relaxation, and education around home practice.

Classes were available twice weekly, and participants were asked to attend at least once a week. All classes were delivered by registered yoga instructors who met regularly to ensure class consistency.

Health education classes were run along the same schedule as yoga – twice weekly for 10 weeks, with participants encouraged to attend at least once a week.

Instructors followed a manual, and covered general health education around topics such as alcohol, smoking, caffeine, nutrition, sleep, pain management, and preventing chronic diseases.

People were assessed up to the end of the intervention at week 10, and then followed up for a further six months. The main outcome of interest was depression score on the QIDS scale at 10 weeks.

In their analyses, researchers took into account class attendance and baseline characteristics, including additional treatments. Nearly all people continued to take antidepressants throughout the study and 40% attended psychotherapy sessions.

What were the basic results?

People in the yoga group attended an average of 8.9 classes over 10 weeks, and those in the health education group attended seven classes over 10 weeks.

There was no significant difference between the groups in QIDS scores at 10 weeks. Scores improved by an average 3.93 points in the yoga group and 3.15 in the health education group. 

However, the researchers did find a significant improvement when they looked at the whole treatment and follow-up period.

Looking at treatment response (greater than 50% reduction in QIDS score), there was no difference between the two groups at 10 weeks. But by six months follow-up, 51% of the yoga group met response criteria compared with 31% of the health education group.

How did the researchers interpret the results?

The researchers concluded that, "Although we did not see a difference in depression symptoms at the end of the intervention period, yoga participants showed fewer depression symptoms over the entire follow-up period. Benefits of yoga may accumulate over time." 

Conclusion

The study will have to be interpreted in the context of other research into yoga and depression. But taken in isolation, it doesn't provide firm evidence that yoga is beneficial for depression.

The findings are applicable to a very specific population group: people with moderately severe depression who took antidepressants (often alongside other psychological therapy) and had no other mental health illness.

They also hadn't previously practised yoga, but must have had an interest in doing so as they responded to advertisements.

This means the groups by no means represent all people with depression symptoms. 

The study was set up to examine the effect on depression score at 10 weeks. There was no statistically significant difference between the groups.

The main outcome in a study is usually the most reliable, as researchers recruit the number of people they need to detect a difference between groups.

But in this study, researchers calculated they needed 75 people in each group, but weren't able to recruit enough. This means the study was underpowered for the main outcome, never mind any secondary outcomes.

And the researchers compared yoga with general health education classes; they didn't compare yoga with usual care, including standard treatment approaches for depression. 

These findings don't alter the current recommendations for the treatment of depression.

The National Institute for Health and Care Excellence (NICE) guidelines recommend initially considering cognitive behavioural therapy (CBT) or structured group physical activity for people with mild to moderate symptoms.

Antidepressants may be prescribed if people have persistent or more severe symptoms, or a history of episodes of depression.

Regular exercise is recommended for everyone – if you have an interest in yoga, there's no reason why the practice shouldn't be part of your treatment.

But it's most important that you first seek help from your GP if you have symptoms of low mood. Treatments like yoga should be complementary to recommended treatments for depression, not an alternative.