The Effects of Bushen Capsule on Episodic Memory in Amnestic Mild Cognitive Impairment Patients: A Pilot Placebo Controlled fMRI Study

Background: Observing the effects of a drug on episodic memory and the underlying brain function has extreme significance in evaluating its therapeutic value in treating amnestic mild cognitive impairment (aMCI). Objective: To observe the effects of Bushen capsule (BSC), a Chinese herbal medicine, on episodic memory in aMCI and further explore the underlying mechanism. Methods: 44 aMCI patients from hospitals and local communities in Beijing were randomly divided into the BSC treatment group (22 patients orally treated with BSC) and the placebo group (22 patients treated with placebo). The duration of intervention lasted for 3 months. Before and after the 3 months treatment, neuropsychological tests and fMRI examinations were carried out to assess cognitive ability and brain activation changes, respectively. Results: Compared to the placebo group, the BSC group presented a significant increase in the AVLT(N5) (p = 0.003) and Stroop (C-B) time (p = 0.002). fMRI results showed a reduction of brain negative activation in the right middle temporal gyrus and a positive activation enhancement in the right putamen among the BSC group after treatment. Meanwhile, the variation in activation values in the right middle temporal gyrus was significantly correlated with the improvement in test values of AVLT(N5), and the variation in deactivation values in the right putamen was significantly correlated with the improvement in test values of Stroop (C-B) time. Conclusions: BSC can improve the behavioral performances of episodic memory in aMCI; this effect may be related to its modulation on the activations of the temporal lobe and the putamen under episodic memory encoding task.