nghiên cứu một số chỉ số chức năng tim - mạch, tâm - thần kinh của sinh viên đại học y thái bình ở trạng thái tĩnh và sau khi thi tóm tắt luận án tiếng anh

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

“life-sustaining element” in every country. Health care for students is the
important task not only for the school but also for the society. This era, the era
of integration with the global boom of science and technology, along with
environmental pollution, internal factors in the human body also become stress
agents (stressors). Stress affects all social classes, including students. There are
many factors causing neuropsychological stress for students during the time at
the university, especially for medical students. Apart from the common
stressors of all students (living conditions, educational conditions…), medical
students have to spend the longest time at the university with very large amount
of theoretical and practical knowledge and many exams, therefore, they are
under high-pressure that cause many psychological functional strain. In the
world, many studies showed that stressors can alter the function of the immune
system, nervous system as well as cardiovascular and endocrine system in
human.
Stress is a reality of life, hence we need to understand the responses to
stresses of the human body in every stressful status. In doing this, we have to
quantify stress levels by using objective measuring indicators. In Vietnam, there
have been some studies on occupational stress of the scientists at the National
Institute of Labor Protection, National Institute of Occupational and
Environmental Health and some universities. However, very few studies have
been conducted on the responses of the endocrine, cardiovascular and
neurological systems of the individual to stress, including studies on students.
From these reasons, we carried out the study "Study on some cardiovascular and
nervous indicators of Thai Binh medical students in control and examination
condition" with the following objectives:
1. Measuring some cardiovascular and neuropsychological indicators
of Thai Binh medical students before examination (control
condition).
2. Evaluating some cardiovascular and neuropsychological and
endocrine indicators of Thai Binh medical students after

intellectual activities (examination condition).
1
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

level of these students increased significantly. Research of Makarenco on
students during the stress test showed a decrease in the influence of
parasympathetic nerve on heart rate and metabolic stimulation but found an
increase of activity of the sympathetic nerve.
In Vietnam, some authors have initially used the method that assess
cardiovascular functions using heart rate and blood pressure in the job
2
with high neuropsychological stress such as work of pilots, soldiers, police,
medical personnel, the commanders of the ship, the operators of automated
machineries, the airport coordinators.
1.1.2. Mathematical statistical indicator of heart rate
In recent years, a number of authors have used the mathematical statistical
indicators of heart rate (MSIHR) of Baevski to evaluate cardiac function.
Baevski is the first author who launched the principle of the index of 100
consecutive RR intervals including: RR interval average (X), heart rate average
(HRA), standard deviation, variation coefficient, mode (Mo), amplitude of
mode and variation interval of RR max and RR min (DX). Stress index is
calculated from above indicator (Stress index = AMo/2.DX.Mo). At a
symposium "Application of mathematical methods to analyze heart rate" the
report of Baevski, Zemaichiche, Zatsiorxki, Parin showed that MSIHR provides
better information to assess the status of the body function, particularly in
profession with high emotional stress.
Recently, MSIHR method has been applied in Vietnam. Studies of Ta
Tuyet Binh, Nguyen Thu ha, Tran Thanh Ha, Nguyen Khac Hai, Nguyen Ngoc
Son showed that intellectual stress and acute stress cause stress index to
increase and heart rate variation to decrease.
1.2. Some neuropsychological functional indicators
Intelligence is the complex mental activity consisting of ability to learn, to
use languages, to solve problems and ability to adapt to society.
1.2.1. Intelligence assessment tests

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:

vision: up to 90%, hearing, touching To evaluate the reaction of the body, for
instance: visual-motor reaction time, there has been a research of Z1 group in
Vietnam Military Medical University based on computer processing technique.
From the result of measuring visual-motor reaction time they calculated
information processing speed. Result of the study of Do Cong Huynh showed
that visual-motor reaction time lessen with age, greater age (less than 18)
shorter reaction time. This proven that information processing speed is getting
better due to age class. The study of Ta Thuy Lan, Tran Thi Loan, Mai Van Hung
depicted similar result and reaction time in women was longer than that of men.
1.2.4. Research on the relation between EEG and intellectual activity
Nervous-emotional stress induced by learning environment after
intellectual activities caused changes in the functional state of the nerve cells.
These changes appear early and can be seen on EEG results. Study of Vu Dang
Nguyen showed EEG indicators changes depend on many factors causing
nervous stress. Tran Thi Cuc reported that amplitude of alpha waves decreased,
while the frequency and index of beta waves increased proportional to
intellectual capacity when thinking. Thus the study of EEG changes at normal
4
and after intellectual work allows us to identify the intellectual performance of
each individual.
1.3. Emotional stress
Emotional stress is a complex process related to social, psychological and
physiological factors. According to Hans Selye, stress is the body's state arising
when strongly affected by factors from outside or inside the body. In that state,
body has to make sudden changes the biological activities, to ensure
homeostasis. The non-specific responses of the body in a state of stress is
considered as general adaptation syndrome. GAS leads the body to a three-stage
response: Alarm, Resistance and Exhaustion. Hypothalamic-pituitary-adrenal
axis (HPA axis) system is the basic theory of GAS. The activation of HPA and
Sympathetic Adrenal Medullary (SAM) leads to increase the body protection

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

procedures.
1.5. Study methods
Analytical cross-sectional study.
1.5.1. Sample size and sample selection
According to Phan Van Duyet, Le Nam Tra et al, samplie size for the
studies of biological indicators is as follows:
222
22


StdN
NtS
n
+
=
With d= ±5% , confidence level: 99%, t= 2,58. CV = 20%, N=300, n was
calculated: n= 78.
- We selected 120 students in each year (60 males and 60 females), hence, the
total of the students for 5 year (from first year to fifth year) was 600 students to
measure biological indicators.
- In measuring ECG, mathematical statistical indicators of heart rate (MSIHR)
and endocrine level, we selected d=10%, p=0,05, t=1,96 and calculated n=15.
- We selected 30 students for each year (15 males and 15 females), hence, the
total of the selected students from first year to fifth year was 30 x 5= 150
(students). Having similar study results, these students were selected for the
purpose of evaluating some indicators before examination (control condition)
and after examination. In the total of 150 students we randomly chose 30
students (15 males and 15 females) to evaluate the changes of blood hormone
level in control condition and after the examination.
1.5.2. Study indicators, measuring tools and methods

- 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,

thinking, Spielberger and Raven test. Indicators in control condition were
measured at the time of student learning and living in normal life, far from the
exam at least 1 month. Every 30 students were measured each time.
- 150 students were selected in the total 600 students, (30 students for each
year unit). Data of ECG and 100 RR intervals of EEG were collected for the first
time (10 students/time of recording ECG and EEG). In addition, blood of 30
students was taken to measure hormone for the first time.
Step 3. Measuring selected indicators of 150 students after the examination.
These indicators were measured right after the exam. We chose the
examination with 60 minutes length (3-4 credits) and 4 students per each class
7
of examination. Each morning 3 classes had examinations; therefore, data of
only 12 students were collected.
Time of measuring indicators was shown in the following diagram (Figure 2.1):
Figure 2.1. Study diagram of the students after examination
Pulse, blood presssure were recorded at 4 working stations; visual-motor
reflex time were evaluated on 4 computers; 100 RR intervals of EEG were
recorded on 2 machines; blood sample for cortisol and catecholamin were also
taken at 4 working stations. Time of finishing all above indicators in 12 minutes
(right after the exam), later, the students took attention, memory, thingking and
emotional tests.
* ECG were recorded after finishing another examination of 60 minutes
length. We chose students who finished the examination after 45, 50, 55, 60
minutes. Time of ECG is 5 minutes after students out of examination room.
* In order to avoid confounding factors, we measured indicators in control
condition at the weekend, in the quiet room with fresh air Examination room
was professionally designed, effects of outside factors were eliminated, air
conditioned. When indicators were measured after the exam, facilities were
arranged next to examination room. Room for measuring indicators was quiet
and air-conditioned.

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
’

5
’
6
’
11
’
1
’
12
’
2
’
8
Diastolic blood pressure (mmHg) 70.71±7.56 67.77±8.19 <0.05
Kerdo index 10.51±13.79 14.7±13.64 <0.05
Table 3.1 showed no difference of pulse rate beetween male and female
students. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) of
males was significantly higher than that of females (p<0.05). Kerdo index of
females was significantly higher than that of males (p<0.05).
1.1. Neuropsychological indicators of the students
1.6.1. Visual-motor reflex time and information processing speed
Results of visual-motor reflex time and information processing speed were
shown in the tables from 3.3-3.6 and figure 3.2.
Table 3.4. Mean of visual-motor reaction time (VMRT) and information
processing speed (IPS)
Indicators Males (A)
n=300
Females (B)
n=300
Total

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

Total 98.61±16.98 100.50±12.68 >0.05
p (1-2), p(1-3),p(1-4),p(1-5), p(2-3), p(2-4), p(2-5), p(3-4),p(3-5) in male and female
students were not significant (p>0.05).
9
Data in table 3.7 showed that IQ score of male and female students in each
year were equivalent and there was no difference of IQ score between male and
female students (p>0.05).
1.6.3. Logical thinking ability of the students
Table 3.13. Number of correct rows (Finding the digit pattern test) of the students
in each year,(
X
SD± )
Sex
Year student
Males (A)
n= 300
Females (B)
n= 300
p (A-B)
1
st
(1) n=120 11.15±2.43 10.93±2.83 >0.05
2nd (2) n=120 10.83±2.73 11.38±3.17 >0.05
3rd

(3) n=120 10.98±3.15 11.25±2.87 >0.05
4th (4) n=120 10.55±2.89 11.48±2.55 >0.05
5th (5) n=120 11.77±2.89 12.38±7.15 >0.05
Total (n=600) 11.06±2.84 11.49±4.10 >0.05
(p (1-2), p(1-3),p(1-4),p(1-5), p(2-3), p(2-4), p(2-5), p(3-4),p(3-5) in male and female students

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

10
the highest and remarkably higher than that of other students (p<0.05). The
number of recorded digits for male and female students was equal for each year
(p>0.05).
1.6.5. Short-term memory of the students
Table 3.18. The number of recorded digits of the student (
X
± SD)
Sex
Year
Male A
(n=300)
Female B
(n=300)
p (A-B)
1
st
(1) n=120 7.47±2.11 8.12±2.03 >0,05
2nd (2) n=120 7.08±1.95 7.18±1.63 >0,05
3rd

(3) n=120 7.78±1.91 8.07±1.76 >0,05
4th (4) n=120 7.65±1.90 7.72±1.79 >0,05
5th (5) n=120 7.30±1.80 7.68±2.21 >0,05
p (1-2), p(1-3),p(1-4),p(1-5), p(2-3), p(2-4), p(2-5), p(3-4), p(3-5) of both sexes >0.05
Total (n = 600) 7.46±1.94 7.75±1.91 >0,05
7.60±1.93
Data in the table 3.18 demonstrated no significant difference in the correct
number of recalled digits of both sexes in each year and between every two
years (p>0.05). This number attained good level.

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
11
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

after the exams,(
X
± SD)
Indicators
Sex
Condition
Male (A)
n = 75
Female (B)
n = 75
p(A-B)
Total
n = 150
Pulse rate
(beats/minu
tes)
control (1)
78.43±7.67 80.21±11.23
>0.05
79.32±9.62
examination
(2)
80.21±12.74 85.27±7.93
<0.05
82.74±7.88
p (1-2)
>0.05 <0.05 <0.05
SBP
(mmHg)
control (1)

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
12
(p<0.05). SBP and DBP of male students were higher than those of female
student in both conditions (p<0.05).

Table 0.25. Analysing mathematical indicators of heart rate on 100 beats ECG
in control condition and after the exams,(
X
± SD)
Indicators Year
Condition
1
st
2
nd
3
rd
4
th
5
th
Pulse
(beats/mi
nutes)
control (A)
72.77±
10.40
73.10±
13.14
76.87±
11.28
72.97±
9.36
76.40±
10.53

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±

0.0131
0.0418±
0.0207
0.0469±
0.0134
0.0556±
0.0148
0.0454±
0.0123
p (A-B)
<0.05 <0.05 <0.05 >0.05 <0.05
Stress
index
(conditio
ning unit)
control (1)
89.96±
85.38
102.96±
114.20
119.32±
121.81
74.36±
72.37
103.69±
118.47
examination
(B)
216.48±
173.54

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
13
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

rd

(3)
4
th

(4)
5
th

(5)
n % n % n % n % n %
Pulse
rate>90
(beats/minut
e)
control (A)
2 6.7 3 10.0 5 16.7 2 6.7 1 3.3
Examination
(B)
8 26.7 11 36.7 2 6.7 0 0.0 5 16.7
p (A-B) <0.05 <0.05 >0.05 - >0.05
SD <0,04
(second)
control (A)
6 20.0 6 20.0 9 30.0 3 10.0 6 20.0
examination
(B)
13 43.3 16 53.3 15 50 6 20.0 10 33.3
p (A-B) >0.05 <0.05 >0.05 >0.05 >0.05

(*) <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

5
th

n % n % n % N % n %
Hypersymp
athetic
control (1) 1 3.3 2 6.7 2 6.7 1 3.3 2 6.7
examination (2) 8 26.7 11 36.7 7 23.3 0 0.0 2 6.7
P (1-2) <0.05 <0.05 >0.05 - >0.05
14
Stress
index≥200
(ĐVĐK)
control (1) 4 13.3 4 13.3 6 20.0 3 10.0 3 10.0
examination (2) 11 36.7 13 43.3 9 30.0 2 6.7 5 16.7
p (1-2) <0.05 <0.05 >0.05 >0.05 >0.05
Hyperparas
ympathetic
control (1) 9 30.0 13 43.3 9 30.0 8 26.7 5 16.7
examination (2) 0 0.0 4 13.3 4 13.3 1 3.3 0 0.0
p (1-2) <0.05 <0.05 >0.05 >0.05 >0.05
Table 3.29 showed that the proportion of first and second year students
who had neurovegetative functional stress with hypersympathetic and stress
index ≥200 (conditioning unit) increased (p<0.05). The proportion of first and
second year students who had neurovegetative functional stress with
hyperparasympathetic decreased (p<0.05).
1.8. Indicators of neuropsychological function of the students in control
condition and after the exams
1.8.1. EEG of the students in control condition and after the exams
Result of EEG of the students in control condition and after the exams was

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)

control (1)
52.53±12.24 54.60±9.78 54.63±11.96 50.80±11.43 54.87±11.32
examination
(2)
45.17±6.23 44.13±6.06 45.93±6.55 47.30±7.20 45.13±6.26
p (1-2)
<0.05 <0.05 <0.05 >0.05 <0.05
Index
(%)
control (1)
52.27±11.32 54.10±9.23 51.67±11.50 49.20±10.21 52.03±10.35
examination
(2)
45.37±7.04 43.9±7.60 44.43±7.01 47.07±7.32 43.07±5.47
15
p (1-2)
<0.05 <0.05 <0.05
>0.05 <0.05
Table 3.31 showed that frequency, amplitude and index (%) of alpha
wave of the first, second and third year students were significantly decreased
(p<0.05) in comparison with control condition. For the fifth year students just
amplitude and index (%) were significantly decreased with p<0.05.
Table 3.34. Frequency, amplitude, index of beta waves in control condition and
after the exams
β
wave
Year
Time
1
st

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)

35.43±5.97 33.00±5.96 33.33±6.61 32.83±6.65 33.50±6.45
examination
(2)
35.33±4.60 36.47±4.71 37.30±4.99 35.17±4.88 37.33±3.88
p (1-2) >0.05 <0.05 <0.05 >0.05 <0.05
Table 3.34 showed that frequency, amplitude and index (%) of beta wave
of all students were significantly increased in comparison with control
condition (p<0.05).
1.8.2. Emotional stress state of the students in control condition and
after the exams
Tables 3.51. Emotional stress level of the students at measurement moment in
control condition and after the exams (According to Spielberger scale)
Time
Emotional stress level
Control (1) Examination (2) p(1-2)
n % n %
Mild 106 70,7 93 62,0 >0,05
Moderate 41 27,3 48 32,0 >0,05
Severe 3 2,0 9 6,0 >0,05
Pathological changes 0 0 0 0
16
Average point 25,3±9,02 28,7±9,97 <0,05
Table 3.51 demonstrated that the proportion of the students with severe
and moderate level was increased but thedifference was not significant
(p>0.05). Average of Spielberger scores was elevated after the exams in
comparison with those of control condition (p<0.05).
1.9. Endocrine indicators of the students in control condition
and after the exams
Cortisol and catecholamines levels of the students in control condition and
after the exams were presented on the tables 3.52-3.53 and figures 3.15-3.16.

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

p (1-2) <0.05 <0.05 <0.05
Table 3.53 showed catecholamine levels in male and female students
significantly increased after the examination with p<0.05 in comparison with
those of control condition.
CHAPTER 4
DISCUSSION
1.10. Some cardiovascular indicators of TBMU students
The study results showed that the pulse rate and blood pressure of the
students were within the limits of ordinary Vietnamese people. In particular, the
pulse rate in male and female students were equal with p> 0.05, systolic blood
17
pressure, diastolic blood pressure in male students was higher than that of
female students with p <0.05. This difference was probably due to the force of
heart muscle contraction and vascular contraction of male students were
stronger than that of female students. Results of our study were similar to that
of Pham Gia Khai, Nguyen Lan Viet on 1793 participants from 16 to 24 years
of age and our study on the students of three colleges and universities in Thai
Binh city. Data from table 3.2 demonstrated that the balanced state of
neurovegetative system accounted for the highest proportion of both sexes
(53.5%). Hypersympathetic state in females students (47%) was higher than
that of male students (37%) (p<0.05). To explain this results, scientists believed
that hormones play an important role in generating the difference of gender in
responses to stress neuropsychological reactions.
1.11. Neuropsychological indicators of Thai Binh Medical
University students
1.11.1. Visual-motor reaction time and information processing speed
Results showed that simple and complex VMRT of male students was
significantly shorter than that of female students (p<0.05) (table 3.4). The
gender differences in VMRT also reported in the study of Mai Van Hung on
students from 18 to 25 years of age. Table 3.3 demonstrated that simple VMRT

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
18
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

small, therefore, we could not make accurate conclusion on this issue.
1.11.3. Thinking, attention and memory ability of the students
The results of our study showed that the memory, attention and thinking
ability of female and male students were similar (p> 0.05), and mostly attaining
good and excellent levels. In which, attention ability of the fourth year students
was significantly higher than that of the others (p<0.05). This difference may be
due to the fact that IQ score of the fourth year students were higher than that of
the others (table 3.7). The results of our study (table 3.17) also indicated that
there was a positive correlation between IQ score and attention ability (r=0.243)
(p<0.05). This results were consistent with those of Mai Van Hung’s study
which researched on university students and showed a tight correlation between
IQ score and attention ability (r=0.675). Thus, the higher IQ score, the better
attention ability is. The proportion of the students with excellent attention
ability in our study is similar to that of Mai Van Hung on student of education
university in Hanoi. This result is compatible with that of Daxiorski which
reported the development of nervous system in both quality and quantity
(increase the number of dendrites, the number of axon branchs and increase
activities of the new synapses), this leads to increasing the flexibility and
adaptation. Short-term memory of male and female students in the same year
and among years was not difference (p>0.05). It is possible that at the age of
19
18-22, brain amines and specific receptors are intensified and played roles in
forming and preserving memory.
1.11.4. Emotional stress state
The frequent occurences of emotional stress state of the students are mostly
maintained in moderate and severe levels (table 3.21). Frequent severe level of the
emotional stress of the first, second, third, fourth and fifth year students were 40%;
33,3%; 50,0%; 30,8% and 33,3% respectively. Severe level of the third year
students is significantly higher than that of the others (p<0.05), the fourth year
students is the lowest. There is a relationship between emotional stress level in male

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
20
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

result on heart rate and blood pressure after the examination was consistent with
that of Zeller, Pramanik. The authors, who studied on psychological stress of
medical students, reported that DBP increased during the whole time of the exams,
but SBP nonsignificantly increased in the both sexes in comparison with that of the
normal days. Some studies of Mohammad, Vrijkote demonstrated both SBP and
DBP of the students increased due to the effect of examination stress. This suggests
that, at first the stress stimulations directly impact the central nervous system when
stress occurs. The impulses arising from the central nervous system activate the
sympatho – adrenergic causing the excretion of catecholamines (adrenaline and
noadrenaline). Catecholamines are transferred into the blood stream and distributed
to different organs in the body. These catecholamines cause different responses to
cardiovascular system to increase SBP and DBP.
Analyzing MSIHR indicated that both male and female students had heart
rate increased, standard deviation of 100 RR intervals decreased, stress index
increased in comparison with those of control condition (p<0.05). The proportion
of the students with severe stress and neurovegetative stress elevated after the
examination (p<0.05). This result was consistent with many studies in the world
as well as in Viet Nam such as Kovaleva’s research on the people with mental
work, Danilova’s research on students, Tran Thu Ha and Ta Tuyet Binh's research
on medical students. The proportion of the first and second year students had
manifestation of cardiovascular functional stress and neurovegetative functional
stress remarkably increased (p<0.05), the third year students having high level of
stress elevated in both control condition and after the exams. The reason for this
consequences may be due to the fact that the first and second year students not
yet adapt of to the sudden changes in living, requiring and studying when they
become the university students. In addition, the third year students begin to go to
the hospital with clinical works and have to learn many difficult professional
subjects plus the overlap between study and exams timetables, therefore, they are
stressful even in control condition while the fourth and fifth year students are
familiar with these circumstances.

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.

1.12.3. The changes of hormone levels of the students in control
condition and after the examination
Data from table 3.52 demonstrated that cortisol level of the male and female
students statistically increased in comparison with control condition (p<0.05). Our
result were consistent with the result of Krahwinkel on students which showed that
cortisol levels in normal status was 0.085μg/dl and after examination was
22
0.315μg/dl (p<0.001). The result in table 3.53 also indicated that catecholamine
level of male and female groups increased significantly after the examination
(p<0.05). Catecholamine level of female students after the examination was higher
than that of male students but this difference was not significant (p>0.05). Our
result was similar to result of Al-Ayadhi Ly on first and second year female
students. Al-Ayadhi Ly reported a significant gain of catecholamine level
intermediately after the test in comparison with that of normal days. Although the
variations of cortisol level and catecholamine level were different in male and
female groups of students and those variations were dissimilar at different times,
those changes evidently indicated that exam pressure is a stressor which causes
psychological stress for students to make their body excrete cortisol and
catecholamine.
CONCLUSION
From the study on some cardiovascular and nervous indicators of Thai
Binh medical students in control condition and after the examination, we got
the following conclusions:
1. Some cardiovascular indicators of 600 Thai Binh medical University
students in control condition
* Cardiovascular indicators
- Pulse rate of male students (79.85±9.02 beats/minute) was similar to that of
female students (79.81±9.02 beats/minute). SBP and DBP of the male students
were 116.03 ± 20.14 mmHg and 70.71±7.56 mmHg respectively. These
indicators of the male students were significantly higher than those of the

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
23