Long-term efficacy of Chinese medicine Bushen Capsule on cognition and brain activity in patients with amnestic mild cognitive impairment

Mild cognitive impairment (MCI), regarded as the prodromal stage before the clinical phase of Alzheimer's disease (AD), has been considered for early intervention. Unfortunately, many trials in this stage with drugs with single-target turned out to be little or no effect. Multi-targeting in nature based on the theory of Traditional Chinese Medicine (TCM) offers another prospect for intervention. Together with advanced functional magnetic resonance imaging (fMRI) technique for more sensitive and objective evaluation, we investigated the long-term therapeutic effects of a TCM compound on cognition and task-related neuronal activity. Sixty amnestic MCI (aMCI) participants from randomly divided into drug (30 with Bushen capsules (BSC)) and placebo (30 with placebo capsules) groups for this 2-years trial. Neuropsychological and N-back task-fMRI data were acquired at baseline and two follow-ups to assess, via linear mixed effect models, the changes of cognitive ability and brain activation over treatments. The drug group, compared with placebo group, exhibited improvement or stabilization in memory measures over time. Analyses of fMRI revealed that the placebo group exhibited higher activation magnitude and spatial extents at left superior parietal lobule; importantly, the greater activation identified in placebo group was related to more decline in the digit span. BSC showed long-term ameliorative effects on cognitive performances in aMCI patients, which might result from the regulation of abnormal brain activities. Our study provided evidence for the potential of TCM in early prevention of AD, as well as the feasibility of neuroimaging biomarkers in clinical trials.