Grey matters: does Bacopa monnieri improve memory performance in older persons

Abstract

Background This thesis investigated the efficacy and safety of Bacopa monnieri in improving memory in healthy Australians over the age of 55-years. A review of the literature showed that memory impairment and dementia are increasingly prevalent in the current demographic climate of an ageing population. As well as the pathological cognitive loss of neurodegenerative disease, many older persons are experiencing memory loss as part of the physiological process of ageing. Bacopa monnieri is a herbal medicine used since antiquity in the traditional Ayurvedic medical system of India for its cognitive enhancing effects. A number of pre-clinical and clinical studies support this traditional usage. Laboratory studies have demonstrated antioxidant and cholinergic actions in the brain as well as improved memory and cognitive performance in animal models. Human trials of Bacopa have also demonstrated improved memory performance. Some of these trials are limited by methodological flaws such as lack of blinding, small sample sizes, or use of outcome measurements which are not well validated. However, a small number of well designed human trials provide evidence for efficacy in cognitive and memory performance improvement. The current study was employed to extend on previous findings by assessing the efficacy and safety of Bacopa in the aged population specifically, as it is in this population that memory impairment becomes apparent. Aims 1. To assess the efficacy of Bacopa monnieri in improving memory in healthy Australians over the age of 55-years. 2. To assess whether the use of Bacopa is associated with side-effects Design A 12-week, randomised, double-blind, placebo-controlled, parallel group clinical trial. Participants Participants were self selected from the general population. They were aged 55-years or over at the commencement of the trial. Participants were without dementia, depression or other serious health conditions and did not use psychotropic medications. Intervention Participants were randomised to one of two treatment conditions, either a tableted extract of Bacopa monnieri called Bacomind™ (300mg/day, standardised to contain at least 40% bacosides), or an identical placebo. Participants attended three clinical evaluations: the first an initial screening session, the second a baseline evaluation of neuropsychological function and subjective memory performance at the commencement of the trial and the third, an end-of-trial outcome evaluation at 12-weeks, during which neuropsychological function and subjective memory performance were again assessed along with side-effects and study compliance. Primary Outcome Measures Rey Auditory Verbal Learning Test (AVLT), Rey-Osterrieth Complex Figure Test (CFT), Memory Complaint Questionnaire (MAC-Q), and Trail Making Test (TMT) Results From 136 people who elected to participate, 103 people met study entry criteria and 98 of these commenced the trial. Of these, 81 participants completed the trial and provided evaluable data for the end point analysis. Bacopa monnieri versus placebo significantly improved verbal learning as well as delayed recall as measured by the AVLT (p\u3c.05). Though improvements were noted in the CFT, MAC-Q and TMT, there were no significant differences between placebo and active groups found for these tests. The Bacopa group reported a higher incidence of gastro-intestinal (GIT) side-effects than the placebo group, these predominantly being increased stool frequency, abdominal cramps and nausea. No other significant adverse effects were found. Conclusions A clinical trial was carried out to assess the effects of 12-weeks administration of Bacopa monnieri (300mg/day) on memory performance in people over the age of 55-years. Primary outcome measures were well validated neuropsychological tests that objectively measured verbal and visual memory and a memory complaint questionnaire that measured subjective memory complaints. The results demonstrated that Bacopa significantly improved memory acquisition and retention in older Australians. This concurs with findings from previous human and animal studies, as well as supports traditional Ayurvedic claims and uses. The beneficial effects on memory observed may be due to previously demonstrated antioxidant and cholinergic effects of the herb on the central nervous system. The use of Bacopa was associated with GIT side-effects, particularly increased bowel movements, nausea and abdominal cramping, findings infrequently reported previously. Possible explanations for these side-effects include GIT irritation by the saponin constituents of the herb, or cholinergic stimulation of autonomic and motor responses in the GIT, or a combination of both of these factors. The side-effects observed in the current study provide supportive evidence that Bacopa may increase cholinergic activity in humans. A worthwhile future extension of the current study would be to assess whether the finding of Bacopa’s efficacy for improving memory performance is replicable in populations with either mild cognitive impairment or early dementia