Exercise, meditation and nutritional supplements in depression: Helpful or not?
Since 1965 it has been clear from clinical trials that antidepressant medications are effective in major depression. However many patients are not keen to take tablets, expressing a wish for more 'natural' forms of treatment. Numerous alternative treatments have been advocated, but is there any evidence that any of these work? Here we briefly review the case for physical exercise, meditation (or mindfulness, as it is now known) and several nutritional supplements.
Alternative treatments as a group can often be criticised because they do not subject themselves to rigorous trials, as is the case with conventional treatments (pharmacological or psychological). This criticism is valid. Indeed it is only within the last 60 years that conventional medicine itself has demanded clear demonstrations of efficacy before a treatment can be licensed for a particular illness. The randomised, double-blind control trial (RCT) is the gold standard by which efficacy is judged. Until recently, very few alternative treatments were subjected to the strict demands of the RCT. But this is changing.
Is physical exercise beneficial in depression?
There is now good evidence that a programme of physical exercise is an effective treatment for depression. Researchers in Brazil conducted a metanalysis in which the results from 10 separate trials were pooled to give an overall finding. (Metanalysis is a powerful method for deciding whether a treatment works. All available trials are scrutinised, and those with no control group or no randomised allocation to drug or placebo are usually excluded on the grounds of being poor quality studies).
“The present meta-analysis concluded that physical exercise, mainly aerobic training, improves the response to depression treatment. However, the efficacy of exercise in the treatment of depression was influenced by age and severity of symptoms“.
The full paper can be read here.
Mindfulness is a currently fashionable psychological approach for the treatment of depression, which has its roots in eastern meditation techniques. The various traditional schools of meditation differ in flavour, but all centre on the idea of mastering an unruly and restless mind. Mindfulness training involves short sessions in which the aim is to direct consciousness towards full immersion in the activity at hand, rather than on the mind's incessant chatter. But does it work?
A recent review from the US attempted to tackle this question. However the authors were unable to reach a definitive conclusion. At present there are not enough studies, of sufficient quality, to yield an answer. They point out that further (and more robust) trials are needed, but they regard mindfulness as a promising approach to depression. They remark:
“Regardless of the various limitations present in the available literature, findings to date have consistently demonstrated that training focused on improving attention, awareness, acceptance, and compassion may facilitate more flexible and adaptive responses to stress“.
The full paper can be read here.
Vitamin deficiencies (especially B-vitamins) can cause neuropsychiatric disorders, although this is very rarely seen now in developed countries. But the idea of supplementation is to provide additional quantities of a specific nutrient in an effort to obtain a therapeutic effect. Three nutrients in particular have attracted attention as possible treatments for depression: folic acid, S-adenosylmethionine (SAM-e) and omega-3 fatty acids. A recent Canadian paper has reviewed the evidence.
Omega-3 fatty acids (fish oils) have been shown to possess antidepressant properties in a metanalysis of 16 trials. SAM-e has also been shown to be effective in a metanalysis of 7 trials. The evidence in support of folic acid has been more limited. One of two trials was positive and further work is needed. The authors conclude:
“Physicians should consider screening for and treating folate deficiency but the benefits of folate supplementation remain unclear. Limited evidence supports the use of omega-3 fatty acids and S-adenosylmethionine, but further research is required“.
The full paper can be read here