Positive modulation of cognition and mood in the healthy elderly volunteer following the administration of Centella asiatica ppt

Positive modulation of cognition and mood in the healthy elderly
volunteer following the administration of Centella asiatica
Jintanaporn Wattanathorn
a,∗
, Lugkana Mator
b
, Supaporn Muchimapura
a
,
Terdthai Tongun
a
, Orapin Pasuriwong
a
, Nawanant Piyawatkul
c
,
Kwanchanok Yimtae
d
, Bungorn Sripanidkulchai
e
, Jintana Singkhoraard
c
a
Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
b
Department of Physiology and Biomedical Science Program, Graduate School, Khon Kaen University, Khon Kaen 40002, Thailand
c
Department of Psychiatry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
d
Department of Otolaryngology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
e

Center for Research and Development of Herbal Health Product, Faculty of Pharmaceutical Sciences,
Khon Kaen University, Khon Kaen 40002, Thailand
Received 21 February 2007; received in revised form 21 November 2007; accepted 28 November 2007
Available online 4 December 2007
Abstract
Aims of this study: Centellaasiaticahasareputationtorestoredeclinecognitive function in traditional medicine and in animal model. However, little
evidence regarding the efficacy of Centella asiatica from systematized trials is available. Therefore, the present randomized, placebo-controlled,
double-blind study investigated the effect of Centella asiatica on cognitive function of healthy elderly volunteer.
Materials and methods: Twenty-eight healthy elderly participants received the plant extract at various doses ranging 250, 500 and 750 mg once
daily for 2 months. Cognitive performance was assessed using the computerized test battery and event-related potential whereas mood was assessed
using Bond–Lader visual analogue scales prior to the trial and after single, 1 and 2 months after treatment.
Results: The results showed that the high dose of the plant extract enhanced working memory and increased N100 component amplitude of
event-related potential. Improvements of self-rated mood were also found following the Centella asiatica treatment.
Conclusion: Therefore, the present findings suggest the potential of Centella asiatica to attenuate the age-related decline in cognitive function and
mood disorder in the healthy elderly. However, the precise mechanism(s) underlying these effects still require further investigation.
© 2008 Elsevier Ireland Ltd. All rights reserved.
Keywords: Centella asiatica; Cognitive function; Event-related potential; Mood; Elderly
1. Introduction
During aging, a gradual deficit is present with regard to cog-
nitive functions, which normally does not severely disturb the
daily life activities related to the physical, mental, or social
functioning in elderly adults. The age-related cognitive decline
has been characterized as a diminution of attentional processes,
episodic and working memory, and processing and psychomo-
tor speed (Nolan and Blass, 1992; Salthouse, 1994; Earles and
Salthouse, 1995; Grady and Craik, 2000; Christensen, 2001).
However, this condition can eventually progress to clinically
∗
Corresponding author. Tel.: +66 43 348394.
E-mail address: (J. Wattanathorn).

recognizable dementia (Chen et al., 2005; Amieva et al., 2005).
Previous studies have demonstrated that age-related impair-
ment in working memory is accompanied by the alteration of
the event-related potential in respond to the auditory oddball
tasks, a most frequent parameters examined in psychophys-
iological studies of cognitive aging (Bashore et al., 1989).
It was found that the latencies of P300 and N100 compo-
nents increased (Oken and Kaye, 1992; Kugler et al., 1993;
Anderer et al., 1996) whereas the amplitudes of these two
components were decreased (Coyle et al., 1991; Nordin et al.,
1999).
Recently, numerous studies have suggested that the age-
related cognitive decline can be prevented (Solfrizzi et al., 1999).
Therefore, a new approach aimed at controlling the decrease in
cognitive function was focused. Numerous previous studies had
0378-8741/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.jep.2007.11.038
demonstrated that fruits, vegetables and medicinal plants could
prevent the occurrence of the neurochemical and behavioral
changes that occurred in aging (Veerendra Kumar and Gupta,
2002; Joseph et al., 2003; Goyarzu et al., 2004).
Centella asiatica (L) urban, a creeping plant in a family
of Apiaceae, is found almost all over the world including in
China, India and Thailand. This plant is claimed to be bene-
fit for managing the central nervous system disorders, skin and
gastrointestinal disorders (Subathra et al., 2005). In addition,
Centella asiatica is also claimed to possess memory enhancing
effect (Veerendra Kumar and Gupta, 2002), anti-inflammatory
(Suguna et al., 1996), wound healing (Suguna et al., 1996), anti-
cancer (Babu et al., 1995) and antioxidant properties (Zainol

et al., 2003). Recently, Centella asiatica products are widely
available in market as cognitive booster. However, supported
document with valid biological data is still very limited. There-
fore, the current study is carried out to determine the effect of
Centella asiatica on the cognitive function and mood in the
elderly.
2. Materials and methods
2.1. Participants
Four male, and twenty-four female healthy elderly volunteers
(mean age 65.05 ± 3.56 years) were recruited to participate in
this study. The Ethical Committee of Faculty of Medicine, Khon
Kaen University, have approved the study, and all subjects gave
written informed consent. Prior to participation, each volun-
teer signed an informed consent form and completed a medical
health questionnaire. All subjects were also undergone exten-
sive medical evaluation in order to ascertain subject suitability
for entering the double-blind phase of trial. Additionally, they
were free of any herbal or prescribed medication that interfered
on the function of nervous system. Habitual smokers consuming
more than 10 cigarettes/day were excluded from this study. All
participants should abstain from caffeine containing products
throughout each study day and alcohol for a minimum of 12 h
prior to the test session. They were divided into four groups:
placebo, CA250, CA500 and CA750 mg/day. Each group con-
tained 1 male and no one dropout from the project. Moreover,
no significant difference about mean age, education and body
mass index among groups were observed.
2.2. Centella asiatica preparation
A standardized extract of Centella asiatica was prepared by
the Center for Research and Development of Herbal Health

Product, Faculty of Pharmaceutical Sciences, Khon Kaen Uni-
versity. All Centella asiatica used in this study was obtained
from Tambon Sila, Khon Kaen Province. The plant was authenti-
cated and kept as voucher specimen at Faculty of Pharmaceutical
Sciences, Khon Kaen University. Standardization and confor-
mity of the extract is assured by strict in-process controls during
manufacture and complete analytical control of the resulting
dry extract. A-day capsule contained a specialized aerial part
extract containing total phenolic content equivalent to tannic
acid = 29.9 mg/g. In addition, the extract also contained asiati-
coside and asiatic acid were presented at concentration of 1.09
and 48.89 mg/g of crude extract, respectively.
2.3. Procedures and treatments
This study was a pilot study conducted as 8-week, double-
blind, placebo-controlled, randomized trial. A random list of
numbers was generated by computer. After being randomly
assigned to various treatment groups. Each participant received
one capsule of placebo or Centella asiatica extract at various
doses ranging 250, 500 and 750 mg once daily. Placebo and
Centella asiatica capsules had the same colour, texture, size and
smell.
All participants were assessed baseline data about cognitive
function, mood and quality of life and then they were assessed
cognitive performance and mood after the single administration,
1 and 2 months of treatment whereas the quality of life was
assessed after 2 months of treatment.
The code for study allocation was only broken when the last
participant completed the entire follow up. Staff involved in the
collection of the study’s endpoints was instructed to follow a
rigorous protocol and not to discuss any issues related to the use

of medication. The review of compliance with medication and
side effects was performed independently by the investigators,
who were also blinded to group allocation. Subjects were asked
to call the study center if they experienced any medical problems
during the 60-day study period. At the end of the study, they were
also asked about adverse events. Laboratory tests were drawn at
baseline and follow-up visits and compared to see whether any
changes suggested adverse events.
2.4. Event-related potential measurement
Event-related potential (N100 and P300 amplitude and laten-
cies) of all subjects were measured using an “oddball paradigm”
(Kennedy et al., 2003). N100 and P300 amplitude and laten-
cies were elicited with a standard auditory oddball paradigm.
Frequent and target tones were presented binaurally through
headphones. Participants were instructed to listen for and
count infrequent target tones (650 Hz, 60 dB, 200 ms), which
occurred randomly amongst 82–90 frequent non-target tones
(1 kHz, 60 dB, 200 ms). Inter-stimulus intervals varied randomly
between 1250 and 3000 ms. The latency range in which the N100
and P300 maximum amplitudes and latencies were determined
was between 65–135 and 280–375 ms, respectively. However,
any peaks outside this range were measured manually, with
preliminary visual checking of all peaks prior to measurement.
2.5. Computerized assessment battery test
The computerized assessment battery test used in this study
has been modified from the CDR computerized assessment bat-
tery test used in hundreds of European and North American
drug trials and sensitive to acute cognitive improvements as well
as impairments with a wide variety of substances (Moss et al.,
1998; Wesnes, 2001). Presentation was performed using note-

book computers with high-resolution VGA colour monitor and,
with the exception of written word recall tests, all responses
were recorded via two-button (yes/no) response box. The entire
selection of tasks took approximately 20 min.
Tests were administered in the following order:
Word presentation: Fifteen words, matched for frequency and
concreteness, were presented in sequence on the monitor for the
participant to remember. The stimulus duration was 1 s, as was
the inter-stimulus interval.
Picture presentation: A series of 20 photographic images was
presented on the monitor at the rate of 1 every 3 s, with a stimulus
duration of 1 s, for the participant to remember.
Simple reaction time: The participant was instructed to press
the ‘yes’ response button as quickly as possible every time the
word ‘yes’ was presented on the monitor. Fifty stimuli were
presented with an inter-stimulus interval that varied randomly
between 1 and 3.5 s. Reaction times were recorded in millisec-
onds.
Digit vigilance task: A target digit was randomly selected and
constantly displayed to the right of the monitor screen. A series
of digits was presented in the centre of the screen at the rate
of 80 min
−1
and the participant was required to press the ‘yes’
button as quickly as possible every time the digit in the series
matched the target digit. The task lasted 1 min and there were
15 stimulus–target matches. Task measures were accuracy (%),
reaction time (milliseconds), and number of false alarms.
Choice reaction time : Either the word ‘no’ or the word ‘yes’
was presented on the monitor and the participant was required

to press the corresponding button as quickly as possible. There
were 50 trials, of which the stimulus word was chosen randomly
with equal probability, with a randomly varying inter-stimulus
interval of between 1 and 3.5 s. Reaction times (millisecond)
and accuracy (%) were recorded.
Spatial working memory: A pictorial representation of a
house was presented on the screen with four of its nine windows
lit. The participant was instructed to memorize the position of
the illuminated windows. In 36 subsequent presentations of the
house, one of the windows was illuminated and the participant
decided whether or not this matched one of the lighted windows
in the original presentation. The participant made their response
by pressing the ‘yes’ or ‘no’ response button as quickly as pos-
sible. Mean reaction times were measured in milliseconds and
the accuracy of responses to both original and novel (distractor)
stimuli were recorded as percentages that were used to derive a
‘percentage greater than chance performance’ score.
Numeric working memory: Five digits were presented
sequentially for the participant to hold in memory. This was
followed by a series of 30 probe digits for each of which the
participant decided whether or not it had been in the original
series and pressed the ‘yes’ or ‘no’ response button as appropri-
ate, as quickly as possible. This was repeated two further times
with different stimuli and probe digits. Mean reaction times were
measured in milliseconds and the accuracy of responses to both
original and novel (distractor) stimuli were recorded as percent-
ages that were used to derive a ‘percentage greater than chance
performance ’ score.
Delayed word recognition: The original words plus 15 dis-
tractor words were presented one at a time in a randomized order.

For each word, the participant indicated whether or not he or she
recognized it as being included in the original list of words by
pressing the ‘yes’ or ‘no’ button as appropriate and as quickly
as possible. Mean reaction times were measured in milliseconds
and the accuracy of responses to both original and novel (dis-
tractor) stimuli were recorded as percentages that were used to
derive a ‘percentage greater than chance performance’ score.
Delayed picture recognition: The original pictures plus 20
distractor pictures were presented one at a time in a randomized
order. For each picture, participants indicated whether or not it
was recognized as being from the original series by pressing the
‘yes’ or ‘no’ button as appropriate and as quickly as possible.
Mean reaction times were measured in milliseconds and the
accuracy of responses to both original and novel (distractor)
stimuli were recorded as percentages that were used to derive a
‘percentage greater than chance performance’ score.
2.6. Subjective mood measurement
The 16 visual analogue scales of Bond–Lader were combined
as recommended by the authors to form three mood factors:
‘alert’, ‘calm’ and ‘content’.
2.7. Statistical analysis
All data are expressed as mean ± S.E.M. Comparisons
between placebo and various doses of Centella asiatica at differ-
ent time points were made using analysis of variance (ANOVA).
Statistical significance was set at p-value < 0.05.
3. Results
3.1. Characteristics of subjects
The baseline data about characteristic of subjects in all groups
were shown in Table 1. No significant difference of all parame-
ters among various groups was observed.

Table 1
Characteristics of subjects
Baseline data Placebo Centella asiatica 250 Centella asiatica 500 Centella asiatica 750
Age 65.88 ± 5.11 67.25 ± 1.39 62.00 ± 4.34 64.75 ± 2.71, p = 0.0511
Education year 11.50 ± 6.21 12.25 ± 5.50 10.38 ± 5.80 14.14 ± 4.91, p = 0.5393
Full scale IQ 102.50 ± 10.61 99.17 ± 16.68 91.40 ± 17.80 99.33 ± 11.91, p = 0.7605
Blood sugar 93.29 ± 9.32 93.25 ± 6.61 89.75 ± 5.95 96.75 ± 11.13, p = 0.4500
Blood pressure 120.13 ± 10.26/77.75
± 5.52
121.50 ± 10.89/78.13
± 7.28
123.50 ± 7.76/80.38
± 2.77
124.75 ± 6.76, p = 0.7465/81.25 ±
4.30, p = 0.4794
Table 2
Mean amplitudes and latencies (S.D.) of event-related potential elicited by oddball paradigm for each group at Fz electrode
Wave Pre-dose baseline Post-dose
Single dose 1 month 2 month
P300 latency Placebo 352.25 ± 27.74 339.63 ± 31.52 342.13 ± 25.67 330.63 ± 27.07
CA250 333.38 ± 31.18 337.75 ± 25.39 353.13 ± 36.99 348.50 ± 31.27
CA500 345.00 ± 20.65 336.00 ± 34.90 343.50 ± 28.16 332.88 ± 29.94
CA750 365.00 ± 31.48 337.38 ± 37.89 343.50 ± 35.27 369.88 ± 42.97
F(3,28) = 1.7785, p = 0.1741 F(3,28) = 0.0167, p = 0.9970 F(3,28) = 0.2035, p = 0.8931 F(3,28) = 2.4673, p = 0.0828
P300 amplitude Placebo 574.38 ± 410.53 557.75 ± 538.67 893.75 ± 871.72 1401.00 ± 1325.39
CA250 1595.00 ± 1918.49 1119.38 ± 960.73 801.00 ± 456.01 816.50 ± 527.87
CA500 890.13 ± 1178.20 1187.25 ± 1181.66 715.50 ± 543.00 1456.50 ± 1367.99
CA750 754.25 ± 686.50 863.00 ± 923.14 914.38 ± 823.24 844.63 ± 523.17
F(3,28) = 1.1192, p = 0.3580 F(3,28) = 0.7552, p = 0.5287 F(3,28) = 0.1381, 0.9364 F(3,28) = 0.1381,
p = 0.9364

N100 latency Placebo 109.75 ± 29.40 100.69 ± 27.74 93.75 ± 22.63 106.63 ± 2359
CA250 103.56 ± 16.27 108.25 ± 22.71 107.25 ± 17.77 107.56 ± 15.67
CA500 100.56 ± 10.13 98.31 ± 8.09 100.25 ± 16.86 95.38 ± 12.20
CA750 94.56 ± 13.36 102.25 ± 12.26 102.38 ± 13.85 106.75 ± 12.74
F(3,28) = 0.5893, p = 0.6271 F(3,28) = 0.4079, p = 0.7485 F(3,28) = 0.7694, p = 0.5209 F(3,28) = 0.9727, p = 0.4195
N100 amplitude Placebo 3241.25 ± 2752.75 3915.38 ± 3059.96 3621.88 ± 1122.45 3655.88 ± 1903.34
CA250 5408.75 ± 3108.07 4297.50 ± 2017.30 4836.25 ± 1961.17 5005.00 ± 1639.17
CA500 4437.50 ± 2414.69 4515.00 ± 2114.88 3265.00 ± 2340.02 4028.13 ± 1944.52
CA750 4895.39 ± 2422.85 4218.75 ± 1219.84 4151.88 ± 1464.45 6691.25 ± 1542.46**
F(3,28) = 0.9687, p = 0.4213 F(3,28) = 0.1684, p = 0.9168
F(3,28) = 1.1748, p = 0.3370 F(3,28) = 4.7179, p = 0.0087
N100 amplitude **p-value < 0.01 compared with placebo (F(3,28) = 4.7179, p < 0.01). N100 latency of CA750 compared with placebo (F(3,28) = 0.9727, p = 0.4195).
3.2. Event-related potential components (ERP)
The effects of Centella asiatica on ERP components were
shown in Table 2. The pre-dose baseline data of latency
and amplitude of both N100 [F(3,28) = 0.9068, p = 0.4503;
F(3,28) = 1.0372, p = 0.3913] and P300 [F(3,28) = 1.7785,
p = 0.1741; F(3,28) = 1.1192, p = 0.3580] showed no significant
difference. After 2 months of treatment with Centella asiatica at
dose of 750 mg/day, the subject’s N100 amplitude significantly
increased [F(3,28) = 4.7179, p = 0.0087] whereas no signifi-
cant change in N100 latency was observed [F(3,28) = 0.9727,
p = 0.4198]. In addition, there were no significant changes
in either the amplitude or latency of P300 [F(3,28) = 0.9180,
p = 0.4449; F(3,28) = 2.4673, p = 0.0828].
3.3. Cognitive measures
Prior to the determination of Centella asiatica on cognitive
function, baseline data and mean pre-dose raw baseline scores
for all four conditions (placebo, 250, 500 and 750 mg Centella
asiatica) for each individual task scores were subjected to a

one-way ANOVA. There were no significant differences on any
measure.
Mean pre-dose baseline raw scores and change from base-
line scores for each condition at each post-dose time point on
the individual task outcome measures are represented in Table 3.
The results showed that the Centella asiatica extract appeared
to decrease the reaction time while increased the %accuracy
of working memory, which indicated that the plant extract
exerted its influence on both speed and quality of working mem-
ory. However, the significant changes in reaction times were
observed only in choice, spatial, numeric and picture reaction
times while the significant changes of %accuracy were observed
only in spatial, numeric, word and picture recognition due to the
high variation of other parameters and limited number of our
subjects.
3.4. Bond–Lader mood scales
Mean raw scores on the ‘alert’, ‘content’ and ‘calm’ factors
obtained from the Bond–Lader visual analogue scales for each
condition across each session are displayed in Table 4.
3.4.1. Alert factor
It was found that the participants’ subjective ratings score
about alert factor of Centella asiatica treated group at dose
of 750 mg/day showed a significant increase, in compari-
son to placebo rating, after 1 and 2 months of treatment
[F(3,28) = 4.0828, p = 0.0016; F(3,28) = 3.7149, p = 0.0229].
3.4.2. Content factor
The present data showed that the rating score about content
factor obtained from Bond–Lader visual analogue scale showed
no significant difference between placebo and various groups of
Centella asiatica treatment.

3.4.3. Calm factor
The effect of Centella asiatica extract on clam factor was
also determined. The results showed that Centella asiatica at
all dosage range used in this study significantly increased the
calm factor after 1 and 2 months of treatment [F(3,28) = 3.3943,
p = 0.0316; F
(3,28) = 4.2124, p = 0.0141].
Table 3
Mean pre-dose baseline raw scores and change from baseline scores for each condition at each post-dose time point on the individual task outcome measures
Measure Pre-dose baseline score Post-dose
1 h 1 month 2 month
Simple reaction
time (ms)
Placebo 626.09 ± 99.94 620.87 ± 88.74 671.21 ± 141.30 693.47 ± 180.39
CA250 640.46 ± 223.62 637.74 ± 233.15 621.38 ± 249.05 573.87 ± 151.92
CA500 636.61 ± 152.38 592.38 ± 134.25 584.19 ± 139.50 580.01 ± 133.32
CA750 615.47 ± 154.01 641.05 ± 227.45 616.98 ± 142.59 586.17 ± 156.73
F(3,28) = 0.0378, p = 0.9900 F(3,28) = 0.1200, p = 0.9476 F(3,28) = 0.3386, p = 0.7975 F(3,28) = 1.0594, p = 0.3820
Digit vigilance
accuracy (%)
Placebo 40.95 ± 25.94 60.00 ± 26.10 49.05 ± 31.43 64.45 ± 23.35
CA250 58.89 ± 22.08 70.00 ± 19.20 56.67 ± 37.71 67.52 ± 31.61
CA500 50.47 ± 26.35 64.76 ± 34.58 68.57 ± 24.26 66.67 ± 29.81
CA750 54.58 ± 26.42 54.17 ± 30.95 71.43 ± 26.31 68.31 ± 32.61
F(3,24) = 0.6100, p = 0.6150 F(3,24) = 0.3848, p = 0.7649 F
(3,25) = 0.8173, p = 0.4965 F(3,25) = 0.0207, p = 0.9958
Digit vigilance
reaction time
(ms)
Placebo 691.21 ± 37.71 684.53 ± 12.28 590.90 ± 190.51 676.01 ± 22.59

CA250 642.43 ± 46.81 678.70 ± 109.13 671.47 ± 75.84 651.12 ± 57.73
CA500 640.38 ± 16.18 762.54 ± 123.85 662.76 ± 45.27 672.85 ± 30.08
CA750 654.24 ± 53.19 654.44 ± 50.38 635.99 ± 38.53 658.75 ± 47.85
F(3,24) = 0.7618, p = 0.5266 F(3,24) = 0.3650, 0.7789 F(3,25) = 0.8499, p = 0.4798 F(3,25) = 0.5326, p = 0.6641
Choice reaction
time (ms)
Placebo 931.22 ± 171.64 883.01 ± 155.60 1012.41 ± 161.47 1031.06 ± 219.37
CA250 967.15 ± 320.46 957.08 ± 338.17 874.25 ± 218.00 834.25 ± 208.19*
CA500 922.34 ± 119.26 911.10 ± 185.14 885.27 ± 213.84 798.65 ± 100.20*
CA750 842.24 ± 124.81 860.17 ± 109.42 854.42 ± 119.19 838.74 ± 106.04*
F(3,28) = 0.5486, p = 0.6532
F(3,28) = 0.2936, p = 0.8296 F(3,28) = 1.2318, p = 0.3167 F(3,28) = 3.1369, p = 0.0411
Spatial memory
(%accuracy)
Placebo 81.94 ± 14.47 78.45 ± 21.10 78.47 ± 17.36 80.21 ± 17.09
CA250 77.78 ± 16.80 86.81 ± 15.55 88.54 ± 11.35 82.29 ± 20.19
CA500 83.68 ± 24.10 91.67 ± 13.28 84.38 ± 15.99 86.78 ± 10.55
CA750 84.79 ± 24.04 84.37 ± 21.92 90.28 ± 12.69 92.36 ± 16.18
F(3,28) = 0.1839, p = 0.9064 F(3,28) = 0.7194, p = 0.5488 F(3,28) = 1.0419, p = 0.3893 F(3,28) = 0.8645, p = 0.4710
Spatial memory
reaction time
(ms)
Placebo 2385.29 ± 761.48 2020.62 ± 441.03 1866.21 ± 357.60 1822.57 ± 594.97
CA250 2116.33 ± 580.06 1954.26 ± 556.26 1906.65 ± 595.45 1714.48 ± 424.70
CA500 2088.62 ± 847.33 1604.90 ± 339.26 1690.60 ± 404.47 1429.49 ± 220.02
CA750 1590.78 ± 220.39 1506.79 ± 218.17* 1486.29 ±
286.23 1290.17 ± 219.74*
F(3,28) = 2.0860, p = 0.1247 F(3,28) = 3.0928, p = 0.0430 F(3,28) = 1.6188, p = 0.2073 F(3,28) = 3.0860, p = 0.0433
Numeric working
memory

(%accuracy)
Placebo 85.42 ± 11.50 88.33 ± 11.13 88.33 ± 13.92 83.75 ± 15.37
CA250 98.33 ± 3.56* 97.50 ± 3.45* 97.09 ± 4.52 96.67 ± 3.09*
CA500 92.50 ± 10.04 95.00 ± 9.09 90.00 ± 19.19 95.00 ± 7.56*
CA750 96.25 ± 5.17* 97.08 ± 3.75* 97.92 ± 1.72 97.50 ± 3.45*
F(3,28) = 3.7734, p = 0.0216 F(3,28) = 2.4765, p = 0.0820 F(3,28) = 1.2977, p = 0.2947 F(3,28) = 4.1683, p = 0.0147
Numeric working
memory reaction
time (ms)
Placebo 1527.65 ± 154.88 1325.31 ± 160.15 1286.51 ± 203.46 1366.07 ± 237.31
CA250 1429.32 ± 707.37 1329.09 ± 467.90 1205.05 ± 382.51 1209.00 ± 271.95
CA500 1531.55 ± 406.20 1268.84 ± 252.98 1251.14 ± 213.54 1170.19 ±
219.44
CA750 1195.95 ± 165.16 1211.97 ± 196.32 1075.45 ± 173.86 984.49 ± 217.75*
F(3,28) = 1.1061, p = 0.3632 F(3,28) = 0.2814, p = 0.8384 F(3,28) = 1.0344, p = 0.3925 F(3,28) = 3.4838, p = 0.0288
Word recognition
(%accuracy)
Placebo 75.42 ± 13.21 76.25 ± 7.65 79.58 ± 14.41 81.24 ± 9.73
CA250 85.00 ± 11.13 79.58 ± 10.15 76.67 ± 14.47 83.33 ± 9.59
CA500 88.33 ± 10.69 82.08 ± 7.95 88.34 ± 5.91 90.83 ± 6.36*
CA750 86.67 ± 7.97 83.75 ± 5.18 90.00 ± 6.42 90.42 ± 4.15*
F(3,28) = 2.2514, p = 0.1043 F(3,28) = 1.3539, p = 0.2771 F(3,28) = 2.7586, p = 0.0609 F(3,28) = 3.1333, p = 0.0412
Table 3 (Continued )
Measure Pre-dose baseline score Post-dose
1 h 1 month 2 month
Word recognition
reaction time
(ms)
Placebo 2164.17 ± 441.54 1815.69 ± 369.90 1652.98 ± 403.65 1647.23 ± 324.29
CA250 2011.64 ± 619.17 1745.24 ± 546.15 1767.28 ± 389.70 1626.07 ± 627.49

CA500 1953.14 ± 705.49 1582.76 ± 334.46 1459.81 ± 309.07 1439.16 ± 278.40
CA750 1658.19 ± 436.07 1555.17 ± 490.51 1450.09 ± 250.96 1400.85 ± 316.46
F(3,28) = 1.1355, p = 0.3517 F(3,28) = 0.6446, p = 0.5928 F(3,28) = 1.6157, p = 0.2080 F(3,28) = 0.7551, p = 0.5287
Picture recognition
(%accuracy)
Placebo 84.38 ± 10.84 86.88 ± 7.99 93.75 ± 5.18 89.38 ± 5.63
CA250 86.88 ± 7.99 91.25 ± 9.54 88.75 ± 9.54 89.38 ± 11.16
CA500 88.75 ± 9.16 85.00 ± 11.34 88.75 ± 6.94 90.00 ± 3.78
CA750 87.50 ± 5.98 83.13 ± 20.17 92.50 ± 9.64 96.88 ± 3.72*
F(3,28) = 0.3600, p = 0.7823 F(3,28) = 0.5614, p = 0.6449 F
(3,28) = 0.8207, p = 0.4934 F(3,28) = 2.3220, p = 0.0967
Picture recognition
reaction time
(ms)
Placebo 2081.19 ± 787.08 1654.23 ± 245.86 1938.81 ± 240.94 1586.45 ± 470.62
CA250 2072.40 ± 480.36 1765.95 ± 409.49 1633.44 ± 282.12*** 1677.62 ± 426.63
CA500 2140.18 ± 958.35 1504.79 ± 321.24 1473.51 ± 209.53*** 1364.52 ± 160.51
CA750 1619.25 ± 285.32 1512.22 ± 290.68 1448.87 ± 198.84*** 1390.04 ± 177.10
F(3,28) = 1.0065, p = 0.4045 F(3,28) = 1.2032, 0.3267 F(3,28) = 7.3583, p = 0.0009 F(3,28) = 1.6066, p = 0.2101
(*) (**) p-value < 0.05 and 0.01 when compared with placebo group, respectively.
4. Discussion
The present study investigated the effect of Centella asiatica
extract on the cognitive performance and mood in the elderly.
The results from this study suggest that the ingestion of single
dose of Centella asiatica can modulate only the reaction time of
spatial memory and %accuracy of numeric working memory in
the healthy elderly.
Recently, it was found that the numeric working memory
process involved the function of lateral prefrontal cortex (PFC)
(D’Esposito et al., 1999; Smith and Jonides, 1999) whereas the

spatial memory was reported to involve hippocampus (Moser
and Moser, 1998). Previous studies demonstrated that the
numeric working memory could be modulated by dopamine,
norepinephrine and other main neurotransmitters (Goldman-
Rakic et al., 2000; Arnsten and Robbins, 2002) and during
spatial memory task, both acetylcholine and serotonin in hip-
pocampus were simultaneously activated (Stancampiano et al.,
1999). Therefore, the acute effect of Centella asiatica on the
numeric memory and spatial memory might partly occur via the
modulation of dopamine and norepinephrine in prefrontal cor-
tex together with the modulation of acetylcholine and serotonin
in hippocampus. However, the possible underlying mecha-
nisms for acute effect of Centella asiatica on the numeric
Table 4
Mean raw scores on the ‘alert’, ‘content’ and ‘calm’ factors obtained from the Bond–Lader visual analogue scales for each condition across each session
Mood Pre-dose baseline score Post-dose
1 month 2 month
Alertness Placebo 67.88 ± 7.92 62.00 ± 8.55 62.50 ± 7.96
CA250 64.88 ± 11.78 68.00 ± 7.13 71.88 ± 6.83
CA500 66.13 ± 6.62 69.75 ± 7.96 68.25 ± 10.50
CA750 71.88 ± 5.11 74.63 ± 5.07** 75.88 ± 7.59*
F(3,28) = 1.0976, p = 0.3665 F(3,28) = 4.0825, p = 0.0159 F(3,28) = 3.7149, p = 0.0229
Contentedness Placebo 40.63 ± 6.16 37.75 ± 7.50 38.25 ± 5.85
CA250 39.00 ± 6.72 40.00 ± 3.89 41.88 ± 3.80
CA500 41.25 ± 3.06 40.88 ± 2.75 40.13 ± 4.79
CA750 42.38 ± 3.54 42.63 ± 3.07 42.38 ± 3.50
F(3,28) = 0.6046, p = 0.6175 F(3,28) = 1.4889, p = 0.2390 F(3,28) = 1.3368, p = 0.2824
Calmness Placebo 15.00 ± 2.00 14.25 ± 2.19 13.38 ± 2.07
CA250 15.38 ± 3.25 16.00 ± 2.00 15.88 ± 2.10*
CA500 15.38 ± 1.19 16.13 ± 0.99 15.63 ± 2.56*

CA750 16.25 ± 2.12 16.75 ± 1.04* 17.00 ± 1.51*
F(3,28) = 0.4398, p = 0.7263 F(3,28) = 3.3943, p = 0.0316 F(3,28) = 4.2124, 0.0141
*p < 0.05 compared with placebo, **p < 0.01 compared with placebo.
memory and spatial memory still required further investiga-
tion.
The repetitive administration of Centella asiatica further to
2 months showed the significant increase in %accuracy of both
numeric working memory and word recognition. In addition,
Centella asiatica also showed significant increase in reaction
time of both numeric working memory and spatial memory.
Thus, the present findings suggest that Centella asiatica can
improve both speed and accuracy of working memory. Since the
results showed the dissociation of temporal profiles in %accu-
racy of numeric working memory and spatial memory reaction
time, thus, it was reasonable to suggest that the relationship
between the Centella asiatica treatment and working memory
following repetitive administration of this substance might not
be a simple relationship.
Interestingly, Centella asiatica also increased the amplitude
of N100 component after 2 months of treatment with high dose
of Centella asiatica whereas no significant changes in N100
latency and P300 latency and amplitude were observed. Previous
studies have demonstrated that N100 component is interpreted
as unitary “sensory gain effect” (Wijers et al., 1996; Hillyard et
al., 1998) and related to attention (Wood et al., 2006) especially
the enhanced processing of the attended location including the
spatial properties of the attend stimulus (Mangun et al., 1993).
Recently, it has been reported that this activity involves the
function of temporal lobe (Sabri et al., 2004).
Previous study demonstrated that hippocampus, an important

area in the inner temporal lobe, played a crucial role on working
memory processing both in human and in primate. Moreover, the
quality of memory also depended on many factors particularly
efficiency of storage and retrieval processes which in turn influ-
enced by attention process (Cohen and Squire, 1980;Tulvingand
Schacter, 1990). In addition, it had been reported that attention
could modify the function of hippocampus (Kentros et al.,2004).
Therefore, the increase in N100 component amplitude in this
study was corresponding to the results which demonstrated the
improve working memory induced by Centella asiatica. Based
on these pieces of evidence, we did suggest that the effect of
Centella asiatica to improve working memory might be associ-
ated with the improve attention manifested as the increase N1
amplitude.
It is very striking that Centella asiatica improves not only
the cognitive performance but also the mood. The high dose of
Centella asiatica could increase calmness and alertness after 1
and 2 months of treatment. In addition, the significant increase in
calmness was also observed after Centella asiatica treatment at
medium and high doses for 2 months. Our present data demon-
strated the improvement of both alertness and calmness together
with the increase attention, therefore we suggested that the plant
extract might possibly improve positive emotion such as alert-
ness and calmness, which in turn improve attention and finally
improve working memory. However, further study about the pre-
cise relationship among various parameters mentioned above
and possible underlying mechanism are still essential.
In conclusion, this study is the first study to demonstrate
the scientific document with many valid biological markers to
support the positive modulation effect of Centella asiatica on

the cognitive function and mood in the healthy elderly. However,
the precise mechanism(s) underlying these effects still require
further investigation.
Acknowledgements
This study was supported by Faculty of Medicine, Center
for Research and Development of Herbal Health Product and
Graduate School, Khon Kaen University. Moreover, gratitude
was also extends to the Cognitive Drug Research Company who
first developed the CDR battery test.
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