Neuroscience Letters 454 (2009) 111–114
Contents lists available at ScienceDirect
Neuroscience Letters journal homepage: www.elsevier.com/locate/neulet
Effects of BT-11 on memory in healthy humans Jun-Young Lee a,1 , Ka Young Kim b,1 , Ki Young Shin b , Beom Young Won b , Hee Yeon Jung a , Yoo-Hun Suh b,∗ a
Department of Psychiatry, Seoul National University Boramae Hospital, Seoul, Republic of Korea Department of Pharmacology, College of Medicine, National Creative Research Initiative Center for Alzheimer’s Dementia and Neuroscience Research Institute, MRC, Seoul National University, 28 Yongon-dong, Jongno-gu, Seoul 110-799, Republic of Korea b
a r t i c l e
i n f o
Article history: Received 23 September 2008 Received in revised form 24 February 2009 Accepted 6 March 2009 Keywords: BT-11 Polygala tenuifolia Memory K-CVLT SOPT
a b s t r a c t We previously reported that BT-11, the extract of dried roots of Polygala tenuifolia Willdenow, had neuroprotective effects and improved scopolamine- and stress-induced amnesia in rats. It also blocked the activity of acetylcholinesterase and enhanced glucose utilization in the rat brain. Therefore, we examined whether BT-11 could enhance memory in healthy humans. This study was a randomized, double-blind, placebo-controlled, parallel-group study of BT-11 in healthy adults. The participants were given capsules of BT-11 or placebo 3 times daily for 4 weeks. The Korean version of the California Verbal Learning Test (K-CVLT) and the Self-Ordered Pointing Test (SOPT) were used to assess verbal memory and working memory, respectively. The subjects in BT-11-treated group showed more significant increases in immediate recall on the K-CVLT than those in the placebo-treated group. In a comparison within each group, the subjects’ scores on most subtests of the K-CVLT were significantly increased by both placebo and BT-11 treatment. Interestingly, the subjects’ scores on the recognition subtest of the K-CVLT were significantly increased by BT-11 treatment but not by placebo treatment. Also, BT-11 treatment significantly reduced the number of errors on the SOPT, whereas placebo treatment did not. We are the first to show that BT-11 has memory-enhancing effects and may be a memory-enhancing drug in healthy adults. © 2009 Elsevier Ireland Ltd. All rights reserved.
Many people experience memory deficits that are accelerated by aging and environmental factors, including stress [5]. Thus, there is increasing interest in memory-enhancing drugs or nootropics. Some reports have demonstrated the effects of memory-enhancing drugs or nootropic drugs on memory in healthy people [10,11,18]. The exact mechanism by which Bacopa monniera acts as a natural nootropic agent has not yet been determined. Pharmacological studies supported that the extracts of B. monniera had memoryenhancing effects [2,11,18]. The extracts had a dose-dependent inhibitory effect on acetylcholinesterase (AChE) activity [3]. Piracetam was also studied for its potential memory-enhancing effects, and it was shown to improve memory and brain metabolism. It was reported that piracetam might act in part by restoring age-related deficits in central cholinergic receptor function [8,14,17]. In addition, cholinomimetics, such as acetylcholine precursors and acetylcholinesterase inhibitors, were developed as potential memory-enhancing drugs. There is some evidence that the enhancement of cholinergic function in healthy humans may improve cognitive processes, including memory [4,7,15].
∗ Corresponding author. Tel.: +82 2 740 8285; fax: +82 2 745 7996. E-mail address: yhsuh@snu.ac.kr (Y.-H. Suh). 1 These authors contributed equally to this work. 0304-3940/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2009.03.024
We previously reported that BT-11, the extracts of Polygala tenuifolia Willdenow, had neuroprotective effects and improved scopolamine- and stress-induced amnesia in rats. BT-11 also blocked acetylcholinesterase activity and enhanced glucose utilization in the rat brain [12,16]. This study investigated the memory-enhancing effects of BT-11 in healthy adults. In this randomized, double-blind, placebo-controlled, parallelgroup study, a total of 55 subjects were recruited from Seoul National University Boramae Hospital and the surrounding community. The exclusion criteria were as follows: (1) taking any other medication for memory improvement (using other cognitive enhancers for at least one month); (2) history of neurological disease, head trauma, stroke, dementia, severe depression or any other physical illness affecting cognitive function; and (3) history of any drug or alcohol dependence within the past 10 years. All participants provided written informed consent, and the review board of Seoul National University Boramae Hospital approved this study. To determine the dose in healthy human, the NOAEL (no observed adverse effect levels) was applied to this study as recommended in the “Guidance for Industry: Estimating the Maximum Safe Starting Dose in Initial Clinical Trials for Therapeutics in Adult Healthy Volunteers” published by the U.S. FDA CDER (U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research). BT-11 was proven safe at
112
J.-Y. Lee et al. / Neuroscience Letters 454 (2009) 111–114
doses up to 0.6 g/kg in preclinical toxicity tests in rats. If the dose of drug was extrapolated to healthy people (60 kg), the maximum human dose was calculated using a safety factor of 100 as follows: 0.6 times 60 divided by 100 gives 360. Thus, the 300 mg dose per person was determined based on the maximum human dose, 360 mg. During the study, each subject in the BT-11-treated group was given a capsule containing 100 mg BT-11 3 times a day for 4 weeks, and each subject in the placebo-treated group received the same dose of placebo. After one month, subjects who had taken less than 80% of the prescribed dosage were excluded from the study. The safety and tolerability of BT-11 were assessed by conducting physical examinations, measuring vital signs, performing electrocardiography, conducting laboratory tests (hematologic tests, blood chemical values, and urinalysis), and recording adverse events. We used the Korean version of the California Verbal Learning Test (K-CVLT) at baseline and after 4 weeks of treatment with medication. The K-CVLT, developed by Delis and colleagues in 1978, is a popular tool used to assess verbal learning and memory [6]. The test has been well standardized for sex and age (for those aged from 20 to 79), and it has a high level of test–retest reliability (0.97) [9]. The test is comprised of 16 words from four different categories so that each category has 4 words. The subjects should memorize all 16 words by completing 5 times of the learning process. During this process, immediate recall is rated by counting the number of words memorized after 5 times. Then, 16 other words from the same categories are presented to interfere with the previous memory, and the subjects are asked to name as many words as possible from the first list (short-delay free recall). Participants are then given a cued recall test in which they are presented with the name of a category as a clue (short-delay cued recall). Twenty minutes later, the subjects were retested using the free recall and cued recall tests in order to assess their delays in memory (long-delay free recall and cued recall). The subjects were asked to complete a recognition task in which they had to respond “yes” or “no” as to whether a word had been on the first list. All scores on these subtests are assigned according to the number of successfully memorized words. In addition, we used the Self-Ordered Pointing Test (SOPT). The test was first described by Petrides and Milner [13], and it includes a series of trials in which a set of images or words are spatially arranged on a display. This test is regarded as an efficient tool for assessing working and strategic memory. The subjects should memorize the items they have previously chosen and point to an item that they had not pointed to before. We tested each subject 4 times using the SOPT with sets of either abstract or representational images: 2 times with a set of 8 stimulus images and 2 times with a set of 12 stimulus images. The total number of errors on this test was counted. The main efficacy analysis was based on a randomized group of participants who completed the study. Safety analysis was performed on all participants who received at least one dose of study medication and who provided any post-baseline follow-up data. Efficacy comparisons between groups were made using independent and paired t-tests. Differences with P < 0.05 were considered statistically significant. SPSS for Windows (release 11.0) was used for the data analyses. In this study, we investigated the safety of BT-11 and placebo as well as medication compliance in healthy adults. Fifty-five subjects participated in this study. Forty-eight participants (BT11-treated group = 23, placebo-treated group = 25) completed the 4-week study, and the other 7 participants (BT-11-treated group = 3, placebo-treated group = 4) dropped out. Study discontinuations were due to patient refusal of ongoing participation (0 participant receiving BT-11 and 3 participants receiving placebo) and, treatment-related side effects (3 participants receiving BT-11 and 1 participant receiving placebo: mild dyspepsia). There was no med-
Table 1 Baseline characteristics of the subjects in the BT-11-treated group and placebotreated group. Variables
Placebo (n = 25)
BT-11 (n = 23)
P value
Age (years) Female (%) Education (years)
39.92 (9.02) 16 (64.0) 15.92 (2.83)
38.04 (12.73) 16 (69.5) 14.55 (2.72)
0.56 0.76 0.10
K-CVLT scores Immediate recall Short-delay free recall Short-delay cued recall Long-delay free recall Long-delay cued recall Recognition
49.40 (10.99) 11.56 (2.82) 12.04 (2.45) 11.76 (2.96) 11.80 (2.81) 14.72 (1.40)
50.43 (8.87) 11.17 (3.39) 11.91 (2.92) 11.65 (2.85) 12.30 (2.82) 14.39 (1.64)
0.72 0.67 0.60 0.90 0.54 0.46
7.60 (3.63)
9.39 (5.11)
0.17
SOPT errors
Values represent mean (standard deviation).
Fig. 1. Immediate recall changes in subjects receiving BT-11 (n = 23) or placebo (n = 25) after 4 weeks. The mean scores of immediate recall were more increased in the BT-11-treated group than in the placebo-treated group after 4 weeks of treatment. P < 0.05 compared with placebo-treated group.
ication compliance in either the BT-11-treated or placebo-treated group. There were no serious treatment-related side effects. The basic characteristics of the subjects in the two groups were shown in Table 1. There were no significant differences in demographic characteristics between the two groups. There were no differences in the baseline scores on the K-CVLT and SOPT between the BT-11-treated and placebo-treated groups. The K-CVLT was comprised of immediate recall, short-delay free recall, shortdelay cued recall, long-delay free recall, long-delay cued recall and recognition subtests. The baseline scores on all subtests of the KCVLT were not statistically different between the BT-11-treated and placebo-treated groups. There was no gender difference within each group or between any of the groups (data not shown). The increase in mean immediate recall score was greater in the BT-11treated group than in the placebo-treated group after 4 weeks of treatment (Fig. 1). There was no significant difference between the two groups on the other subtests of the K-CVLT, including shortdelay free recall, short-delay cued recall, long-delay free recall, long-delay cued recall and recognition (Table 2). In a compariTable 2 The K-CVLT changes in memory measures in subjects receiving BT-11 (n = 23) or placebo (n = 25) after 4 weeks. Score changes
Placebo
BT-11
P value
Short-delay free recall Short-delay cued recall Long-delay free recall Long-delay cued recall Recognition
1.40 (1.8) 1.64 (1.75) 1.60 (1.85) 1.88 (1.62) 0.52 (1.56)
2.22 (2.63) 1.91 (2.37) 1.96 (2.1) 1.78 (1.83) 0.91 (1.2)
0.212 0.651 0.535 0.846 0.336
Values represent mean changes (standard deviation).
J.-Y. Lee et al. / Neuroscience Letters 454 (2009) 111–114
113
Table 3 Scores on subtests of the K-CVLT measured before and after treatment with BT-11 (n = 23) or Placebo (n = 25) for 4 weeks. Score changes
Placebo
BT-11
Before
After
P value
Before
After
P value
Immediate recall Short-delay free recall Short-delay cued recall Long-delay free recall Long-delay cued recall Recognition
49.40(11.00) 11.56 (2.81) 12.04 (2.45) 11.76 (2.96) 11.80 (2.81) 14.72 (1.40)
59.00 (10.35)a 12.96 (2.42)a 13.68 (2.05)a 13.36 (2.21)a 13.68 (2.21)a 15.24 (0.97)
0.000 0.001 0.000 0.000 0.000 0.108
50.43 (8.88) 11.17 (3.39) 11.91 (2.92) 11.65 (2.85) 12.30 (2.81) 14.39 (1.64)
63.69 (8.69)a 13.39 (2.27)a 13.83 (1.87)a 13.61 (2.57)a 14.09 (2.04)a 15.30 (1.18)a
0.000 0.001 0.001 0.000 0.000 0.001
Values represent mean (standard deviation). a P < 0.01 compared pre-treatment to post-treatment within each group.
Table 4 Scores on the SOPT measured before and after treatment with BT-11 (n = 23) or placebo (n = 25) for 4 weeks. Score changes
Placebo Before
SOPT errors
7.60 (3.63)
BT-11 After 6.76 (4.26)
P value 0.254
Before 9.39 (5.11)
After 7.60 (3.67)
P value a
0.007
Values represent mean (standard deviation). a P < 0.01 compared pre-treatment to post-treatment within each group.
son within each group after taking BT-11 or placebo for 4 weeks, both the BT-11-treated and placebo-treated groups showed significant changes on the immediate recall, short-delay free recall, short-delay cued recall, long-delay free recall and long-delay cued recall subtests of the K-CVLT (Table 3). Notably, the BT-11-treated group showed statistically significant differences in recognition scores after 4 weeks, but the placebo-treated group did not. In SOPT, although the baseline scores in the BT-11-treated group (7.6 ± 3.63) were higher than in the placebo-treated group (9.39 ± 5.11, p = n.s.), there was no statistically significant difference between the two groups (Table 1). The SOPT scores were remarkably decreased by BT-11 treatment for 4 weeks, but not by placebo treatment (Table 4). Therefore, we know that memory increased slightly in the BT-11treated group. In this study, we examined whether 4 weeks of BT-11 administration could improve memory in comparison with placebo in healthy adults. The scores on immediate recall test were significantly greater in the BT-11-treated group than in the placebotreated group (Fig. 1), although there was no significant difference between the two groups on the other subtests of the K-CVLT (Table 2). In a comparison within each group, the results indicated that scores of recognition on the K-CVLT, unlike other subtests, were increased in the BT-11-treated group after 4 weeks of treatment but not in the placebo-treated group (Table 3). There was also a significant decrease in the number of errors on the SOPT after 4 weeks of BT-11 administration but not after 4 weeks of placebo treatment (Table 4). A paired t-test showed significant improvements in the scores of recognition on the K-CVLT and SOPT error numbers in the BT-11-treated group but not in the placebo-treated group, however, these differences in improvement between the two groups were not observed in the independent t-test. These results may suggest that more than 4 weeks of BT-11 treatment were required. These tests were performed in healthy young adults. Although there was a placebo effect, the increase in the subjects’ scores on the recognition and immediate recall subtests of the K-CVLT and the decrease in the number of SOPT errors were only observed in the BT-11-treated group. Thus, BT-11 may have beneficial effects on healthy humans. In another study, the memory and learning enhancer, B. monniera, has been reported clinically for its acute (5-week) and chronic (12week) effects on cognitive function. Acute administration of 300 mg of B. monniera extract resulted in no significant changes in cognitive function when compared to baseline values. On the other hand, significant cognitive effects were observed at 12 weeks [1].
We already found that BT-11 improved memory function in healthy elderly people after 8 weeks of treatment. In the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) assessment packet, another memory test, the total scores were significantly increased more in the BT-11-treated group than in the placebotreated group (data not shown). These results suggest that BT-11 improves recognition as well as working and immediate memory, but these findings must be confirmed in future studies involving more subjects and a longer study period. We previously reported that BT-11 had protective effects against learning and memory impairments caused by scopolamine- and stress-induced amnesia in rats [12,16]. BT-11 also inhibited acetylcholinesterase activity in a dose-dependent and non-competitive manner. This finding suggests that BT-11 may be a therapeutic agent that can be used to maintain acetylcholine levels in the brain and to improve memory [12]. We are the first to demonstrate that BT-11 has memory-enhancing effects and may be a memory-enhancing drug in healthy adults. Acknowledgements This study was supported by a National Creative Research Initiative Grant (2003–2009) from the Ministry of Science and Technology, the Republic of Korea and in part by BK21 Human Life Sciences, the Republic of Korea and by Braintropia Co. Ltd., the Republic of Korea. References [1] Bacopa monniera, Monograph, Altern. Med. Rev. (2004) 79–85. [2] C. Calabrese, W.L. Gregory, M. Leo, D. Kraemer, K. Bone, B. Oken, Effects of a standardized Bacopa monnieri extract on cognitive performance, anxiety, and depression in the elderly: a randomized, double-blind, placebo-controlled trial, J. Altern. Complement. Med. 14 (2008) 707–713. [3] A. Das, G. Shanker, C. Nath, R. Pal, S. Singh, H. Singh, A comparative study in rodents of standardized extracts of Bacopa monniera and Ginkgo biloba: anticholinesterase and cognitive enhancing activities, Pharmacol. Biochem. Behav. 73 (2002) 893–900. [4] K.L. Davis, R.C. Mohs, J.R. Tinklenberg, L.E. Hollister, A. Pfefferbaum, B.S. Kopell, Cholinomimetics memory. The effect of choline chloride, Arch. Neurol. 37 (1980) 49–52. [5] D.J. de Quervain, B. Roozendaal, J.L. McGaugh, Stress and glucocorticoids impair retrieval of long-term spatial memory, Nature 394 (1998) 787–790. [6] D.C. Delis, J.H. Kramer, E. Kaplan, B.A. Ober, The California Verbal Learning Test, Research Edition. New York: Psychological Corporation (1987). [7] M.L. Furey, P. Pietrini, G.E. Alexander, M.B. Schapiro, B. Horwitz, Cholinergic enhancement improves performance on working memory by modulating the
114
[8]
[9] [10]
[11]
[12]
[13]
J.-Y. Lee et al. / Neuroscience Letters 454 (2009) 111–114 functional activity in distinct brain regions: a positron emission tomography regional cerebral blood flow study in healthy humans, Brain Res. Bull. 51 (2000) 213–218. Z. He, Y. Liao, M. Zheng, F.D. Zeng, L.J. Guo, Piracetam improves cognitive deficits caused by chronic cerebral hypoperfusion in rats, Cell. Mol. Neurobiol. 28 (2008) 613–627. J.K. Kim, Y. Kang, Normative study of the Korean–California Verbal Learning Test (K-CVLT), Clin. Neuropsychol. 13 (1999) 365–369. C. Lanni, S.C. Lenzken, A. Pascale, I. Del Vecchio, M. Racchi, F. Pistoia, S. Govoni, Cognition enhancers between treating and doping the mind, Pharmacol. Res. 57 (2008) 196–213. P.J. Nathan, S. Tanner, J. Lloyd, B. Harrison, L. Curran, C. Oliver, C. Stough, Effects of a combined extract of Ginkgo biloba and Bacopa monniera on cognitive function in healthy humans, Hum. Psychopharmacol. 19 (2004) 91–96. C.H. Park, S.H. Choi, J.W. Koo, J.H. Seo, H.S. Kim, S.J. Jeong, Y.H. Suh, Novel cognitive improving and neuroprotective activities of Polygala tenuifolia Willdenow extract, BT-11, J. Neurosci. Res. 70 (2002) 484–492. M. Petrides, B. Milner, Deficits on subject-ordered tasks after frontal- and temporal-lobe lesions in man, Neuropsychologia 20 (1982) 249–262.
[14] H. Pilch, W.E. Müller, Piracetam elevates muscarinic cholinergic receptor density in the frontal cortex of aged but not of young mice, Psychopharmacology 94 (1998) 74–78. [15] J. Rusted, P. Eaton-Williams, Distinguishing between attentional and amnestic effects in information processing: the separate and combined effects of scopolamine and nicotine on verbal free recall, Psychopharmacology 104 (1991) 363–366. [16] K.Y. Shin, B.Y. Won, C. Heo, H.J. Kim, D.P. Jang, C.H. Park, S. Kim, H.S. Kim, Y.B. Kim, H.G. Lee, S.H. Lee, Z.H. Cho, Y.H. Suh, BT-11 improves stressinduced memory impairments through increment of glucose utilization and total neural cell adhesion molecule levels in rat brains, J. Neurosci. Res. (2008). [17] L. Stoll, T. Schubert, W.E. Müller, Age-related deficits of central muscarinic cholinergic receptor function in the mouse: partial restoration by chronic piracetam treatment, Neurobiol. Aging 13 (1992) 39–44. [18] C. Stough, L.A. Downey, J. Lloyd, B. Silber, S. Redman, C. Hutchison, K. Wesnes, P.J. Nathan, Examining the nootropic effects of a special extract of Bacopa monniera on human cognitive functioning: 90 day double-blind placebo-controlled randomized trial, Phytother. Res. (2008).