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Exploring curcumin for depression and anxiety

Depression sucks, and traditional depression treatments aren’t so great either. According to the literature, what effects might curcumin have on this mood disorder?

Study under review: Efficacy of curcumin, and a saffron/ curcumin combination for the treatment of major depression: A randomised, doubleblind, placebo-controlled study

Introduction

You may have heard that depression is caused by a chemical imbalance in the brain. Specifically, by low levels of serotonin. Serotonin belongs to a class of neurotransmitters known as monoamines, which are involved in the regulation of mood. So it’s reasonable to think that low levels of serotonin cause depression. But, how true is the claim that low levels of serotonin cause depression, and why is it so popular?

In the 1960s doctors noticed that drugs that increased levels of monoamine neurotransmitters had an antidepressant effect[1]. Several other trials at the time found similar results, leading to what researchers call the monoamine hypothesis of depression[2]. The dominance of this hypothesis in the late 1900s is why antidepressant drugs that increase monoamines in the brain have become one of the first lines of treatment for depression.

Unfortunately, the trials that support the use of these drugs were at high risk of bias[3], and methodological flaws may have led to an overestimation of the actual effects. A new body of research[4] has also shown that the factors that lead to depression are more complicated than in the monoamine hypothesis. For instance, experimental studies[5] have shown that depleting monoamines in the brains of healthy volunteers does not produce depressive-like symptoms. Several new hypotheses are pictured in Figure 1, focusing on factors such as neuroinflammation[6], hypothalamic-pituitary-adrenal (HPA) axis dysfunction[7], and circadian rhythm abnormalities[8], have emerged and gained traction amongst neuroscientists. It is possible that augmenting standard therapies with adjuncts that address these factors could lead to improvement in depressive symptoms.

Figure 1: Mechanisms involved in depression

References: Miller & Raison. Nat Rev Immunol. 2016 Jan. | Anacker et al. Psychoneuronendocrinology. 2011 Apr. | Delgado. J Clin Psychiatry. 2000

One of the possible adjuncts is curcumin, a yellow compound found in turmeric. It has anti-inflammatory[9], neuroprotective, antioxidant, and HPA-modulating effects[10], which have led researchers to explore whether it is effective for reducing symptoms of depression. Previous research on it has shown some promise. One mini meta-analysis[11] of four randomized trials and two non-randomized trials found that curcumin was effective for reducing symptoms of depression, especially atypical depression[12], a form of depression characterized by hypersomnia, increased appetite and weight gain. However, ERD readers should know that meta-analyses are only as good as the studies they include, and some of these studies had limitations. Some trials were too short[13], underpowered, lacked placebo groups[14], or were not randomized[15]. Also, none of these trials were longer than eight weeks.

The current study under review sought to address these limitations by running a randomized controlled trial (RCT) for 12 weeks with a larger sample size than previous studies. In the current study, the researchers also wanted to see whether different doses of curcumin would result in different outcomes and whether saffron, a spice with antidepressant effects via the same mechanisms as curcumin, would display greater efficacy when combined with curcumin.

Depression is a complex mood disorder that is likely a result of multiple factors. Antidepressant drugs, which are the first line of treatment for depression, may not be as effective as first thought. Researchers have explored alternative treatments that address multiple factors, such as curcumin and saffron supplementation, which have both shown antidepressant effects in previous studies. This study sought to expand on the knowledge acquired from previous studies with a more robust study design.

Who and what was studied?

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Other Articles in Issue #30 (April 2017)