Neuroimaging Functional Magnetic Resonance Imaging Task-Based Dorsolateral Prefrontal Cortex Activation Following 12 Weeks of Cosmos caudatus Supplementation Among Older Adults With Mild Cognitive Impairment

Abstract

Background: Cosmos caudatus (CC) is traditional Asian vegetable, commonly consumed among the Southeast Asian population. It has been reported to be high in flavonoids and might potentially improve brain activity among older adults with mild cognitive impairment (MCI). The effect of CC in brain activation improvement using neuroimaging is yet to be discovered.

Purpose: To investigate the effects of CC supplement on brain activity using functional magnetic resonance imaging (fMRI) among older adults with MCI.

Study type: Prospective, randomized, double-blind, placebo-controlled trial.

Population/subjects: Twenty older adults with mild cognitive impairment (60-75 years old), 14 of them (70%) were female subjects.

Field strength/sequence: A 3.0-T, T1-weighted anatomical images, T2*-weighted imaging data, A single shot, gradient echo-echo planar imaging (EPI) sequence.

Assessment: All subjects were asked to consume two 500 mg capsules of either CC supplement or placebo (maltodextrin) daily for 12 weeks. Cognitive function was measured using validated neuropsychological tests (i.e. Mini-mental State Examination and Digit Span) and task-based fMRI (N-back and Stroop Color Word Test) at baseline and 12th week. Brodmann's area 9, 46 and anterior cingulate cortex were selected as the regions of interest to define dorsolateral prefrontal cortex (DLPFC) in fMRI analysis.

Statistical tests: Normality test was performed with the Shapiro-Wilk test. Two-way repeated ANOVA determined the intervention effects of the CC supplementation on brain activity after adjustments for covariates. Significance level at P < 0.05 for independent-t test and Chi square test; adjusted P < 0.0042 for two-way repeated ANOVA after Bonferroni correction.

Results: Findings showed significant improvements in digit span (partial η² = 0.559), increment in right DLPFC activation while performing 1-back task (partial η² = 0.586) and left DLPFC activation while performing Stroop Color Word Test (SCWT) (congruent) task (partial η² = 0.432) at 12th week of CC supplementation.

Conclusion: CC supplementation might have the ability to improve DLPFC activation, potentially leading to improved working memory among older adults with MCI after 12 weeks of administration.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 4.

Keywords: Cosmos caudatus; DLPFC; brain activity; cognition; fMRI.