Issue:
112
Page: 38-39
Meta-analysis Finds Curcumin to Be an Effective Adjunct Treatment for Major Depressive Disorder
by Heather S. Oliff, PhD
HerbalGram.
2016; American Botanical Council
Reviewed: Al-Karawi D, Al Mamoori DA, Tayyar Y. The role of
curcumin administration in patients with major depressive disorder: Mini
meta-analysis of clinical trials. Phytother Res. 2016;30(2):175-183.
Nearly 50% of patients with major depressive disorder (MDD)
discontinue treatment due to adverse events. Therapies with better tolerability
are needed to treat this chronic disease that negatively affects quality of
life and increases morbidity. The antidepressant activity of curcumin, a
chemical constituent of turmeric (Curcuma longa, Zingiberaceae) rhizome, has
been evaluated in numerous clinical trials. This meta-analysis evaluated the
safety and efficacy of curcumin in the treatment of MDD.
The search of the literature and presentation of the results
followed the guidelines of the Preferred Reporting Items for Systematic Reviews
and Meta-Analyses (PRISMA). The following databases were searched from 1986
through 2016: PubMed, Scopus, PsycINFO, Evidence-Based Medicine Guidelines,
DynaMed, JAMAevidence, and the Cochrane Library. The following key words were
used: curcumin, depression, MDD, efficacy, and effect. Reference lists of
identified papers were hand-searched. Included articles met the following
criteria: (1) human study, (2) quantitative analysis, (3) intervention and
control group, (4) curcumin was an independent intervention, (5) study
addressed only MDD, (6) depression was measured with standardized scales, and
(7) the study was published in English. The Quality Assessment Tool for
Quantitative Studies was used to assess study quality and an overall rating of
methodological quality was assigned. This rating system classifies studies as
strong (no weak ratings), moderate (one weak rating), or weak (two or more weak
ratings). For the meta-analysis, the data from all studies were converted into
Hamilton Depression Rating Scale scores according to published methods. Small
sample sizes were adjusted with the Hedges’ adjusted g formulation of
standardized difference in means. The random-effects model and generic inverse
variance method were used to combine the results since the studies had
different design characteristics.
A total of 1,757 studies were identified, and six met all
inclusion criteria (four randomized controlled trials, one crossover study, and
one open-label study).1-6 The six studies included a total of 342 patients (n =
177, curcumin; n = 165, control). All patients received antidepressant therapy
in addition to either curcumin (1,000 mg per day in five studies or 500 mg per
day in one study) or placebo. In regard to methodological quality, five were
rated as strong, and one was rated as moderate. The meta-analysis showed a
significant reduction in MDD symptoms with curcumin treatment compared with
control (P = 0.002). This outcome was not influenced by any single study.
Several subgroup analyses were conducted with the following outcomes: (1)
curcumin had a significant benefit in middle-aged patients (P = 0.002) but not
older-aged patients (specific age ranges not described); (2) curcumin had a
significant benefit in patients treated for more than six weeks (P = 0.001),
but not patients treated for less than six weeks; (3) the 1,000 mg per day of
curcumin had a significant benefit (P = 0.002), but the 500 mg per day did not;
and (4) curcumin had a significantly greater benefit in patients with MDD only
compared with patients with MDD plus comorbidities (P = 0.001).
In two of the studies,4-5 researchers used BCM-95 (Arjuna
Natural Extracts Ltd.; Aluva, Kerala, India), a standardized preparation of
curcuminoids blended with the essential oil of turmeric. In three of the
studies,1-3 the curcumin treatment also contained piperine, a chemical
constituent of black pepper (Piper nigrum, Piperaceae) fruit that has been
shown to increase the bioavailability of curcumin. The authors of the
meta-analysis provided no further descriptions of the curcumin preparations
used in the six studies. Subgroup analysis showed that treatments containing
piperine had smaller benefits than curcumin alone (P = 0.05). However, the
authors note that two of these studies used a low (potentially subtherapeutic)
dose of piperine, and the study that used a higher dose of piperine used a low
dose of curcumin (which may have been too low to produce an effect). Therefore,
the piperine meta-analysis should be viewed with caution.
The pooled data had minimal heterogeneity as assessed with
the I2 index. Funnel plot analysis showed no publication bias. Adverse events
were digestive/gastrointestinal complaints (e.g., gastritis, nausea),
tachycardia, flushing, and giddiness. Two of the six studies reported no
adverse events; adverse effects in the placebo groups were not reported.
According to the authors, this is the first meta-analysis of
the effect of curcumin on MDD. The authors conclude that curcumin is effective
in reducing symptoms of depression in patients with MDD who are taking
antidepressants. They also note that curcumin is more effective in middle-aged
patients, at a dose of 1,000 mg per day, and when taken for more than six
weeks. The authors acknowledge that the results should be interpreted with
caution because only six studies were included and only two doses of curcumin
preparations were evaluated. They also acknowledge that the dose of piperine
and/or curcumin may not have been optimal, and
that long-term outcomes were not assessed despite that MDD is a chronic
condition.
The authors used rigorous methodology in conducting the
meta-analysis. These encouraging results indicate that larger and
longer-duration clinical trials of curcumin in the treatment of MDD are
warranted. There were no conflicts of interest.
—Heather S. Oliff, PhD
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