MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENSE
VIETNAM MILITARY MEDICAL UNIVERSITY
NGUYEN THI HIEN
STUDY ON SOME CARDIOVASCULAR
AND NERVOUS INDICATORS OF THAI BINH
MEDICAL STUDENTS IN CONTROL
AND EXAMINATION CONDITION
Speciality: Physiology
Code: 62 72 01 07
DOCTOR OF PHILOSOPHY DISSERTATION
HAnOi - 2013
THE PROJECT COMPLETED
In VIETNAM MILITARY MEDICAL UNIVERSITY
Advisors:
Assoc. Prof. PhD. Tran Dang Dong
Assoc. Prof. PhD. Vuong Thi Hoa
Reviewer 1:
Assoc. Prof. PhD. Le Thu Lien
Reviewer 2:
Assoc. Prof. PhD. Le Van Son
Reviewer 3:
Assoc. Prof. PhD. Nguyen Trong Hung
The doctoral dissertation has been defended at the Council Assessment of
the dissertation at Vietnam Military Medical University
at 8.30 am. - April 9th 2013.
THE DISSERTATION AVAILABLE AT:
- National Library of Vietnam
- Library – Vietnam Military Medical University
- Library – Thai Binh Medical University
INTRODUCTION
Students are high quality workforce for the society in the future, they are

intellectual activities (examination condition).
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NEW SCIENTIFIC CONTRIBUTIONS OF THE DISSERTATION
- Providing data of some cardiovascular and neuropsychological indicators
of 600 male and female medical students from first year to fifth year in
control condition.
- Detecting changes of cardiovascular, neurological and endocrine function
after intellectual activities (after examination) of medical students. After
the exam, participants had cardiovascular strain indicator increased, ECG
changed, cortisol level as well as catecholamine level elevated.
- The results of the dissertation contributes to the development of some
biological indicators and provides scientific evidences to propose solution
to lessen stress, improve health and intellectual property of students.
THE STRUCTURE OF THE DESSERTATION
This desstertation consists of 152 pages: Introduction: 2 pages, Background: 41
pages, Methods: 20 pages, Results: 46 pages, Disscusion : 40 pages, Conclusion:
2 pages, Proposal: 01 page, 60 tables, 25 figures and 139 references.
CHAPTER 1
BACKGROUND
1.1. Cardiovascular indicators
1.1.1. Heart rate and blood pressure
Heart rate and arterial blood pressure are the simplest indicators to evaluate
the operational capacity of the human body. These indicators are easy to
measure, can be long-term or repeated measure. The variations of them are
easily recognizable because when the labor intensity or the emotional level
increased, those indicators rose follow. Stressful work causes increased heart
rate, increased blood pressure by stimulating the adrenal sympathetic nervous
system. Research of Droogleever on Dutch PhD students found that although
blood pressure did not change significantly during the examination, but the
density of peripheral Benzodiazepine receptor, allopregnanolon and cortisol

The first scientist proposed the test ideas and coined the term "mental test"
as Francis Galton (1822-1911). After that the intelligence assessment tests were
alternately appeared such as: Binet-Simon (1905), Stanford-Binet test (1916),
Wechsler scale (1939), Gille test (1944), Wisc test (1949) and Raven test
(1960). Many intelligence tests have been widely used in countries around the
world such as: Russia, USA, Poland, Germany and France. Raven test is
officially used by UNESCO to diagnose human intellect since 1960.
In Vietnam, before 1980s of twentieth century, there have been some
researchs at Hanoi National University of Education applying intelligence tests
in evaluating learning outcomes of students such as: study of Tran Ba Hoanh,
study of Nguyen Long. From 1980s up to now, intelligence tests have been
widely applied in our country. The two facilities have made important
3
contributions in this field are Institute of Education Sciences of Vietnam and
Center for kid research in Hanoi. These facilities have done many researchs on
intellect of primary, secondary, high school pupils as well as university
students.
1.2.2. Attention, memory and thinking
Attention, memory and thinking of human beings are active, complex
processes that have important roles in learning and processing information in
many different fields of activities. In Vietnam, Tran Thi Loan found the
increase of attention ability of male and female pupils is also in the period of
increase memory ability and in the period of development, improvement of
structure and function of the brain. The study of Lai The Luyen showed the
most clear appearance and the highest rank of stress on students was hard to
focus and then hard to remember. According to J. Lazaus, stress causes memory
injury, mental instability, inability to concentrate, hesitance, indecisive, lack of
attention, empty-headed These symptoms usually appear.
1.2.3. Visual - motor reaction time, information processing speed
Information comes to human in various ways, through many chanels:

activities, mobilizes energy to help the body in responses to stimuli which cause
stress. Physiological responses to stress are not only non-specific, but also
physiological changes depending on environment, working conditions, social
factors, stress experiences of individual. Many hormones of the endocrine
glands involve in reactions, in which cortisol and catecholamines are the most
important hormones and considered as the indicators of stress. Learning stress
can be seen as a good study model of natural stress of human. When students
are stressed, the most clearly physical consequences of the students are difficult
to concentrate, easy to tense and inactive to work. However, stress is not always
cause negative impacts on the students. The presence of stress sometimes is
necessary, which greatly affect the motivation and interest in their learning.
CHAPTER 2
STUDY PARTICIPANTS AND METHODS
1.4. Study participants
Study participants are 600 students from 1st year to fifth year of full-time
training course of general medical doctor in Thai Binh Medical University. We
did not choose 6th year students because they needed time to prepare for
graduation.
Average age of the students has been shown in the table 2.1.
Table 0.1.Tuổi trung bình của sinh viên các năm thuộc trường ĐH Y Thái Bình
Student
Age
1st year 2nd year 3rd year 4th year 5th year
X ± SD 21,76±1,21 22,31±0,82 23,49±1,30 24,61±1,07 25,52±0,91
5
Selection criteria: Participants having BMI, pulse, blood pressure, hearing and
vision in the normal range, not suffering from acute or chronic diseases,
especially cardiovascular, neurological and mental diseases; not using any
neuroleptics or stimulants for 3 days before and during the study time; being
voluntary to take part in the study and willingness to follow all study

- Pulse rate in quiet status. Use stopwatch.
- Blood pressure in quiet status (mmHg). China sphygmomanometer was used
and standardized with mercury sphygmomanometer before measurement,
using the Korotkov method. Calculate Kerdo index.
6
- Assessment of cardiovascular function and vegetative nervous system by
using mathematical statistical indicator of heart rate (Baevski RM et al.) on
Cadiofax 3 channels ECG machine of Japan.
- Assessment of intellectual capacity is determined by the ongoing test of Raven
frame types A, B, C, D, E.
- Visual-motor reflex time and information processing speed is measured on
computer using software of testing physiological psychology written by Ngo
Tien Dung, Do Cong Huynh et al.
- Attention ability was assessed by the method of "Arranging the jumbled
digits".
- Logical thinking ability was assessed by method of "Finding the digit
patterns".
- Short-term memory was assessed by the method of "Look and remember digits"
- Emotional stress was evaluated using Spielberger test.
- EEG was recorded by Neurofax 9001 machine of NIHON KOHDEN, Japan.
- Measuring serum cortisol levels on the Immulite 2000 machine of Siemens
using immunoassay method, in the Department of Biochemistry, National
Institute of Haematology and Blood Transfusion.
- Measuring blood catecholamin levels using Smaznov method, in the
Department of Biochemistry, Thai Binh Medical University.
1.5.3. Study procedures
Step 1. Study location, training to unify process and data collection techniques.
Step 2. Measuring selected indicators in control condition.
- 600 students were measured the selected indicators such as: pulse, blood
pressure, ECG, visual – motor reflex time, guiding for memory, attention,

Data processing: Data were processed using biostatistical methods.
CHAPTER 3
STUDY RESULTS
1.6. Some cardiovascular indicators of Thai Binh medical
University students
Results of cardiovascular indicators have been shown in table 3.1, 3.2 and figure
3.1.
Table 3.1. Some cardiovascular indicators of the students (
X
± SD)
Sex
Indicators
Males n=300 Females n=300
p
Pulse rate (beats/minute) 79.85±9.02 79.81±9.02 >0.05
Systolic blood pressure (mmHg) 116.03±20.14 107.60±11.86 <0.05
2
’
Examination
Pulse, Blood
pressure
Visual-motor
reflex time
EEG
Blood
sample
60
’
3
’

n=600
p(A-B)
Simple VMRT (ms) 290.25 ±63.25 304.46±70.69 297.35±67.39 <0.05
Complex VMRT (ms) 402.24±74.70 427.49±77.23 414.87±76.95 <0.05
IPS(bit/s) 7.15±3.30 6.89±3.32 7.06±3.30 >0.05
Data in the table 3.4 showed that simple VMRT and complex VMRT of
male students significantly shorter than that of female students (p<0.05). Means
of IPS in male and female students were not different (p>0.05).
1.6.2. Intellectual ability according to Raven test
Result of IQ score and its classification was shown in the tables from 3.7-
3.9 and figures 3.3 and 3.4.
Table 3.7. IQ scores of the students, (
X
± SD)
Sex
Year student
Males (A)
n= 300
Females (B)
n= 300
p (A-B)
1
st
(1) n=120 98.90±18.65 99.80±13.22 >0.05
2nd (2) n=120 98.00±18.40 98.75±14.72 >0.05
3rd

(3) n=120 96.30±21.81 101.40±9.98 >0.05
4th (4) n=120 100.10±12.35 101.75±13.24 >0.05
5th (5) n=120 99.75±11.73 100.75±11.95 >0.05

were not significant (p>0.05).
Table 3.13 showed that the number of correct rows of male and female
students in the same year and among other years were not different (p>0.05). This
number in male and female student was equivalent (p>0.05). Logical thinking
ability of the student attained good level.
1.6.4. Attention ability
Table 3.15. Number of recorded digits of the students (
X
± SD)
Sex
Year
Males
n=300
Females
n=300
p
1
st
(1) n=120 15.87±7.75 14.88±7.65 >0,05
2nd (2) n=120 14.65±7.90 13.72±7.66 >0,05
3rd

(3) n=120 15.12±8.06 14.22±7.83 >0,05
4th (4) n=120 18.55±6.20 19.25±6.33 >0,05
5th (5) n=120 14.67±6.90 14.22±7.69 >0,05
p(4-1), p(4-2), p(4-3), p(4-5) <0.05 <0.05
Total (n=600) 15.77±7.49 15.26±7.68 >0,05
15.51±7.58
Result in the table 3.15 indicated that the number of recorded digits in male
and female students was similar. This number of the fourth year students was

1.6.6. Emotional stress state
Result of evaluating emotional stress state was presented in the tables 3.20-
3.22 and figure 3.12.
Table 0.22. Emotional stress state of the students

Sex
Levels
Male
n=300
Female
n=300
p OR 95%CI
n % n %
Mild 10 3.3 6 2.0 >0.05 1.0
Moderate 193 64.3 160 53.3 <0.05 0.4 0.2-1.2
Severe 94 31.3 131 43.7 <0.05
0.6 0.4-0.8
Pathological changes 3 1.0 3 1.0 >0.05
Table 3.22 showed that emotional stress state of the students mostly were
moderate or severe level. There was a relation between emotional stress levels
of male and female students. The proportion of female students with severe
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level or worse was significantly higher than that of male students (OR=0.6;
95% CI: 0.4-0.8).
1.7. Some cardiovascular indicators of the students in control condition
and after the exam
Results of pulse rate, blood pressure and mathematical statistical indicator
of heart rate on 100 beats ECG of the students in control condition and after the
exam were presented in the tables 3.23-3.30 and figure 3.13.
Table 0.23. Pulse rate, blood pressure of the students in control condition and

114.60±11.08 104.40±8.85
<0.05
109.50±11.22
examination
(2)
114.40±9.56 107.93±10.69
<0.05
111.17±10.62
p (1-2)
>0.05 <0.05 >0.05
DBP
(mmHg)
control (1)
70.67±7.55 65.20±7.32
<0.05
67.93±7.90
examination
(2)
72.07±7.97 68.80±8.13
<0.05
70.43±8.19
p (1-2)
>0.05 <0.05 <0.05
Table 3.23 demonstrated that after the exams, pulse, diastolic blood
pressure of both sexes were significantly increased in comparison with those of
control condition. In particular, systolic blood pressure of female students also
elevated. Pulse rate of female students was higher than that of male students
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(p<0.05). SBP and DBP of male students were higher than those of female
student in both conditions (p<0.05).

examination
(B)
80.50±
11.22
83.47±
16.05
76.43±
12.69
72.93±
9.01
80.10±
11.79
p (A-B)
<0.05 <0.05 >0.05 >0.05 >0.05
SD
(second)
control (A)
0.0675±
0.0276
0.0631±
0.0258
0.0599±
0.0278
0.0657±
0.0276
0.0604±
0.0218
examination
(B)
0.0418±

312.92±
346.21
191.60±
175.27
88.51±
53.50
162.28±
189.13
p (A-B)
<0.05 <0.05 >0.05 >0.05 >0.05
Data in the table 3.25 showed that heart rate and stress index of first year
and second year students were increased but standard deviation (SD) of 100 RR
intervals significantly decreased (p<0.05). Third year and fifth year students
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had SD of 100 RR intervals remarkably decreased (p<0.05). There was no
difference between two conditions of these indicators of fourth year students.
Tables 3.27. Students with high cardiovascular functional strain according to
MSIHR in control condition and after the exams
Indicators
Year
Condition
1
st

(1)
2
nd

(2)
3

(*) <0,05 p(3-4)B* , p(3-5)B* , p(4-2)B*
Stress index
≥200
(conditioning
unit)
control (A)
4 13.3 4 13.3 6 20.0 3 10.0 3 10.0
examination
(B)
11 36.7 13 43.3 9 30.0 2 6.7 5 16.7
p (A-B) <0.05 <0.05 >0.05 >0.05 >0.05
(*) <0,05 p(4-1)B*, p(4-2)B*, p(4-3)B*
Data in table 3.27 showed that after the exam, the proportion of first and
second year students had cardiovascular functional strain ¾ times higher than that of
control condition (p<0.05). Third year student had high cardiovascular functional
strain in both control condition and after the exams in that SD<0.04s higher than that
of third and fifth year students (p<0.05). After the exams, fourth year students had
stress index>200 (conditioning unit) lower than that of other students (p<0.05).
Table 0.29. Students with neurovegetative functional stress
Indicator
Year
Time
1
st
2
nd
3
rd
4
th

described in the tables 3.31-3.39 and figure 3.14.
Table 3.31. Frequency, amplitude, index of alpha waves in control condition
and after the exams
Αlpha
wave
Year
Time
1
st
2
nd
3
rd
4
th
5
th

Frequency
(Hz)
control (1)
9.63±1.29 9.85±1.32 9.77±1.41 9.57±1.35 9.17±1.15
examination
(2)
9.07±0.74 8.90±0.80 8.87±0.73 9.03±0.72 8.93±0.74
p (1-2)
<0.05 <0.05 <0.05
>0.05 >0.05
Amplitude
(µV)

2
nd
3
rd
4
th
5
th

Frequency
(Hz)
control (1)
15.23±0.97 15.23±1.10 14.93±0.98 15.00±0.79 15.37±1.10
examination
(2)
15.73±0.79 16.10±0.76 15.90±0.76 15.93±0.79 15.93±0.74
p (1-2)
<0.05 <0.05 <0.05 <0.05 <0.05
Amplitude
(µV)
control (1)
15.75±1.10 15.50±0.80 15.70±1.15 15.62±0.95 15.67±0.79
examination
(2)
17.30±0.60 17.60±0.72 17.50±0.63 17.47±0.78 17.53±0.73
p (1-2)
<0.05 <0.05 <0.05 <0.05 <0.05
Index
(%)
control (1)

Table 3.52. Serum cortisol level (nmol/l) of the students in control condition
and after the examination (
X
± SD)
Sex
Time
Males (A)
n= 15
Females (B)
n= 15
p(A-B) Total
n=30
Control (1) 272.12±69.47 235.83±68.79 >0.05 254.43±70.81
Examination (2) 446.41±94.49 439.00±136.66 >0.05 442.60±116.8
p (1-2) <0.05 <0.05 <0.05
Table 3.52 showed cortisol levels in male and female students significantly
increased after the examination with p<0.05 in comparison with those of control
condition.
Table 3.53. Cactecholamines levels (µmol/l) of the students in control condition and
after the examination
Sex
Time
Males (A)
n= 15
Females (B)
n= 15
p(A-B) Total
n=30
Control (1) 37.59±5.57 33.44±6.88 >0.05 35.46±6.53
Examination (2) 56.00±6.91 57.11±10.57 >0.05 56.57±8.87

of male and female students in every year were significant differences (p<0.05).
The fourth year students had the shortest VMRT and the fifth year students had
the longest VMRT. This is probably due to the fact that the fourth year students
have better attention ability than the others (p<0,05) (table 3.15). This study
also indicated a negative correlation between attention ability and simple or
complex VMRT (r = -0,159 và r= -0,128; p<0.05) (table 3.17). It means that the
better attention ability the shorter VRMT (quick reaction). Our result is similar to
that of Mai Van Hung on educational students which reported the negative
correlation between attention ability and hearing, visual-motor reaction time.
Information processing speed of the students (table 3.4) was 7,06 ± 3,30. This
indicator mainly attained good and excellent level and no difference was found
among every year and between male and female students. Information processing
speed in our study is higher in comparison with that of Nguyen Thi Ngoc
Thanh’s study. This is probably due to the difference in age and environment. At
the age of 20 the coordination of activities of nervous-muscle reached the level
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of completeness, the speed of synaptic neurotransmission is faster, thus
shortening VRMT in comparison with that of the younger.
1.11.2. Intellectual capacity according to Raven test
Result of this study (table 3.7) showed that IQ scores of male and female
students were: 98,61 ± 16,98 and 100,50 ± 12,68, respectively. There was no
difference of IQ scores between male and female students in every year as well
as whole school. IQ score of the fourth year students was higher than that of
others (p>0.05). Our result was lower than that of Tran Thi Cuc studying on the
second year students of Hue University Tran Thi Loan researching on education
students and Mai Van Hung studying on education students. This difference
may be partly due to the fact that the students in other school had opportunities
being acquainted with Raven test in psychological subject, but the students of
Thai Binh Medical university used this test for the first time. In addition, the
number of the participants of these study was different and sample size was

and female students. The proportion of female students with moderate emotional
stress is lower (OR=0.4, 95%CI: 0.2-1.2), but the proportion with severe level of
emotional stress is significantly higher than that of the male students (OR= 0.6;
95% CI = 0.4- 0.8). According Jiongjiong Wang, in male emotional stress state,
right prefrontal cortex (regulating negative emotions) is more active, while the
orbital cortex - frontal left (blocking role) is less stimulated. This phenomenon
related to cortisol, a kind of stress hormone. In contrast, stress in women
primarily activated the limbic system of the brain which independently worked
of concentrations of cortisol. The results of our study are similar to those of
Jadoon on 815 medical students in Multan. This study also showed strain rate of
first-year students, 2nd year, 3rd year, fourth year and last year is 45.86%,
52.58%, 47.14%, 28.75% and 45.10%. The proportion of the female students
suffering from depression was higher than that of the male students (OR= 2.05;
95% CI=1.42- 2.95; p<0.001). According to Hashmat, causes of stress in medical
students were overload of studying (90,8%), lack of exercises (90%) and lengthy
examination (77,5%). The proportion of the medical students with high level of stress
in our study was higher than that of Le The Luyen’s study on stress expression of
students in University of Education which showed that students with highly stressful
level accounted for 10,8%, stress level accounted for 49,8%. This evidence proved
that medical students suffered from higher pressure than other students.
1.12. Some cardiovascular, neuropsychological functional
indicators and endocrine level of Thai Binh medical
students in control condition and after the examination
1.12.1. Some cardiovascular functional indicators and endocrine level of
Thai Binh medical students in control condition and after the examination
Pulse rate, blood pressure of the students in control condition and after the examination
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Result in the table 3.23 showed that pulse rate and SBP of the students
increased after the examination (p<0.05), SBP significantly elevated in female
students particularly (p<0.05) in comparison with that of control condition. Our

21
1.12.2. Some neuropsychological indicators of the students in control
condition and after the exam
- EEG variations
After the examination, EEG indicators of the students such as: frequency,
index and amplitude of alpha wave decreased but these indicators of beta and
delta waves statistically increased in comparison with those of control condition
(p<0.05). The variations of EEG indicators according to school year were
consistent with emotional stress status as well as cardiovascular functional
stress. Our result was consistent with that of Tran Thi Cuc, the author realized
that amplitude and index of alpha wave decreased but amplitude and index of
beta wave increased when thinking. The study of Umriukhin on EEG of students
in normal situation and before exams showed that students with high index of alpha
wave before exams will have better scores.
- Short-term memory capacity of the students in control condition and after the exam
Our study indicated that memory capacity of both sexes significantly
increased after the exam (p<0.05). Increasing memory capacity immediately
after the exam was caused by rapidly releasing catecholamine and early
influencing glucorticoid through the activation of membrane receptors.
Glucocorticoids interact with noradrenaline in basolateral amygdala, then modulate
memory process in prefrontal cortex, hippocampus, amygdala and other brain areas
and finally enhance learning new information and retrieval old information.
- Emotion characteristics of the students in control condition and after the exam
The result in table 3.51 showed that the proportion of the students had
moderate and severe levels of emotional stress nonsignificantly increased in
comparison with that of control condition (p>0.05). After the exam, average
Spielberger score statistically increased (p<0.05). The causes of emotional stress
were timing pressure, intellectual and psychological strains. It is noticed that exam
stress caused functional changes of Sympathetic Adrenal Medullary and
Hypothalamic-pituitary-adrenal system.

female students (107.60±11.86 mmHg and 67.77±8.19 mmHg) with p<0.05.
The proportion of the female students with hypersympathetic (47%) was
significantly higher than that of the male students (p<0.05).
* Neuropsychological indicators
- IQ score of male students (98.61±16.98) was similar to that of the female
students (100.50±12.68). IQ score of normal and good levels was dominant.
According to the Raven test, intellectual capacity of the students was positively
but not tightly correlated to learning ability (r=0.134).
- Simple and complex VMRT of the male students were significantly shorter
than those of the female students (p<0.05). Fourth year students had the shortest
VMRT in comparison with other students (p<0.05). Logical thinking ability and
short-term memory of the male and female students was similar. These
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