Effects of 12-Week Bacopa monnieri Consumption on Attention, Cognitive Processing, Working Memory, and Functions of Both Cholinergic and Monoaminergic Systems in Healthy Elderly Volunteers

Abstract

At present, the scientific evidence concerning the effect of Bacopa monnieri on brain activity together with working memory is less available. Therefore, we aimed to determine the effect of B. monnieri on attention, cognitive processing, working memory, and cholinergic and monoaminergic functions in healthy elderly. A randomized double-blind placebo-controlled design was utilized. Sixty healthy elderly subjects (mean age 62.62 years; SD 6.46), consisting of 23 males and 37 females, received either a standardized extract of B. monnieri (300 and 600 mg) or placebo once daily for 12 weeks. The cholinergic and monoaminergic systems functions were determined using AChE and MAO activities. Working memory was assessed using percent accuracy and reaction time of various memory tests as indices, whereas attention and cognitive processing were assessed using latencies and amplitude of N100 and P300 components of event-related potential. All assessments were performed before treatment, every four weeks throughout study period, and at four weeks after the cessation of intervention. B. monnieri-treated group showed improved working memory together with a decrease in both N100 and P300 latencies. The suppression of plasma AChE activity was also observed. These results suggest that B. monnieri can improve attention, cognitive processing, and working memory partly via the suppression of AChE activity.

Figure 1

HPLC-chromatograms of B. monnieri extract (2 mg/mL) containing 5% (w/w) of total saponins comprising a mixture of (1) Bacoside A₃, (2) Bacopaside II, (3) Bacopaside X, (4) Bacopasaponin C, and (5) Bacopaside I.

Figure 2

Effect of B. monnieri on percent change from baseline of (a) reaction time of power of attention, (b) continuity of attention, (c) quality of working memory, and (d) reaction time of speed of memory. * = P < 0.05, ** = P < 0.01, *** = P < 0.001 when compared to placebo-treated group.

Figure 3

Effect of B. monnieri on percent change from baseline of Acetylcholinesterase activity throughout the study period. (N = 20/group) * = P < 0.05, ** = P < 0.01, *** = P < 0.001 when compared to placebo.

Figure 4

Effect of B. monnieri on percent change from baseline of Monoamine oxidase activity throughout the study period. (N = 20/group).

Figure 5

Hypothetical diagram of the possible underlying mechanism for the cognitive enhancing effect of B. monnieri in healthy elderly volunteers.