CURCUMIN SUPPLEMENTATION IMPROVES CERTAIN ASPECTS OF COGNITION AND ALLEVIATES INFLAMMATION, INDEPENDENT OF ADIPOSITY
Sarker, Marjana R.
Franks, Susan F.
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The study was designed to investigate the effects of curcumin on blood based biomarkers and mental health in a chronic mid-life obese state. 3 groups were studied, mice on a regular diet, on a calorically restricted diet and on a regular diet supplemented with curcumin. These mice were kept on their respective diets for 12 weeks. Two behavioral studies to investigate mental health in particular memory, were utilized. Our results conclude that curcumin dietary treatment positively affects specific domains of mental health possibly by the lowering of inflammation but this effect is independent of fat loss. Purpose (a): Midlife obesity has been recently associated with cognitive impairment that may be attributed to chronic, obesity-related inflammation and oxidative stress. Commonly used laboratory mice fed ad libitum are an analogue of weight gain in middle aged humans, since accumulating fat is more often the result of food intake exceeding energy expenditure and not solely because of a high fat diet. The current study addressed the hypothesis that curcumin supplementation, by attenuating obesity and adiposity -related inflammation, would improve cognition in a midlife obesity animal model. Methods (b): C57BL/6J male mice were maintained under ad libitum (AL) feeding until they reached peak weight at 15 months of age, as a model of inactivity-related weight gain. The mice were subsequently assigned in groups of 19 to: (i) remain on AL, (ii) receive 30% caloric restriction (CR) or (iii) receive curcumin in their AL diet (1000 mg/kg diet, CURC) for 12 weeks. Mice underwent tail bleeds for the inflammatory markers, interleukin 6 (IL-6) and C-reactive protein (CRP) and, after 8 weeks of dietary treatment, spatial cognitive function was tested using a Morris water maze, followed by testing for cognitive flexibility using a discriminated avoidance, serial reversal task. Visceral (VAT) and subcutaneous (SAT) adipose tissue was collected after 12 weeks of the treatments. Results (c): Mice maintained on CR weighed significantly less than mice on the CURC and AL diets by the third week of treatment. Food intake of the CURC group was significantly higher than AL. Mice on CR and CURC diets took fewer trials than AL to reach criterion during the second reversal session of discriminated avoidance, suggesting that both conditions improved cognitive flexibility. However, there were no significant differences between the groups in their spatial cognitive performance. Mice maintained on CR had significantly less VAT and SAT compared to mice on CURC and AL. Curcumin supplementation did not significantly impact IL-6 levels but it did reduce CRP relative to AL mice. Conclusions (d): Results suggest that in a midlife obesity animal model, curcumin supplementation has positive effects on frontal cortical functions that may be linked to an anti-inflammatory action. It appears that these effects may be independent of adiposity. Curcumin intake may also facilitate energy expenditure or diminish efficiency, as suggested by the increase in energy intake in the absence of weight loss in the CURC mice. Future studies will determine the metabolic and cognitive consequences of higher curcumin doses.