Effects of Curcuma longa extract on cognitive function in healthy participants with subtle cognitive weaknesses within the normal range: a randomized, double-blind, placebo-controlled trial.

INTRODUCTION: The dietary spice Curcuma longa (C. longa), also known as turmeric, has various physiological effects. A mixture of hot water extract and supercritical carbon dioxide extract of C. longa (CLE) containing the anti-inflammatory compounds turmeronols A and B and bisacurone has demonstrated anti-inflammatory activity. Although neuroinflammation is known to be associated with cognitive impairment, the effects of CLE on cognitive function remain unclear. In the present study, we investigated the effects of CLE and of its active ingredients, turmeronols A and B and bisacurone, on cognitive function. METHODS: We conducted a randomized, double-blind, placebo-controlled trial in healthy participants aged 40 to 69 years with subtle cognitive weaknesses within the normal range. Participants were allocated to study groups based on a randomization schedule and took two capsules containing CLE (CLE group, n = 20) or two placebo capsules (placebo group, n = 20) daily for 24 weeks. Cognitive functions were evaluated at weeks 0, 12, and 24 using various cognitive assessments. RESULTS: Among 35 cognitive endpoints, the CLE group showed significantly higher orientation scores at 24 weeks than the placebo group, as measured by the eye-tracking cognitive assessment and the Japanese version of the Montreal Cognitive Assessment. In addition, the CLE group showed significantly higher attention scores at 24 weeks than the placebo group, as measured by the eye-tracking cognitive assessment. CONCLUSION: These results suggest the possibility that CLE might improve the cognitive functions associated with orientation and attention. TRIAL REGISTRATION: UMIN-CTR, UMIN000054532. Registered 31 May 2024, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000062302.