Inflammation can be a contributing factor for depression.
That may be one of the reasons why this substance produced results in this study.
The research was conducted as a double-blind, placebo controlled study on major depression (Lopresti AL, et al. 2015).
The purpose was not to investigate if reducing inflammation would improve depression, but instead to measure other biomarkers to see if 500 mg twice daily of a patented form of curcumin for 8 weeks would reduce depressive symptoms, and to identify other potential mechanisms of action for curcumin.
We already know curcumin will reduce inflammation.
It was found that the group treated with curcumin experienced reduced symptoms of depression and elevation of urinary thromboxane B2 and substance P while the control group did not. That means they were eliminating both thromboxane B2 and substance P.
Substance P has been associated with pain and a variety of other conditions including depression (Hepfer I, Lieb K, 2003).
Thromboxane B2 has also been documented to be increased in depression (Lieb J, et al. 1983).
As you saw there several reasons why curcumin would improve your mood, and also more than one reason why it also may decrease pain.
Herpfer I1, Lieb K. Substance P and Substance P receptor antagonists in the pathogenesis and treatment of affective disorders. World J Biol Psychiatry. 2003 Apr;4(2):56-63.
Lieb J, Karmali R, Horrobin D. Elevated levels of prostaglandin E2 and thromboxane B2 in depression. Prostaglandins Leukot Med. 1983 Apr;10(4):361-7.
Lopresti AL1, Maes M2, Meddens MJ3, Maker GL4, Arnoldussen E3, Drummond PD5. Curcumin and major depression: a randomised, double-blind, placebo-controlled trial investigating the potential of peripheral biomarkers to predict treatment response and antidepressant mechanisms of change. Eur Neuropsychopharmacol. 2015 Jan;25(1):38-50. doi: 10.1016/j.euroneuro.2014.11.015. Epub 2014 Dec 5.
The raw material in the new Better Curcumin is absorbed 65 times better than regular Curcumin and is very bio-available. Research has also shown that curcumin is very effective for reducing inflammation.