Psychological Status of Freshmen with Different Levels of their Regulatory System Activity

1Department of Normal Physiology, Saratov State Medical University, Saratov, Russia. 2Department of Hospital Therapy, Saratov State Medical University, Saratov, Russia. 3Coordinating Center for Fundamental Research, National Medical Research Center for Therapy and Preventive Medicine, Moscow, Russia. 4Department of Innovative Cardiological Information Technology, Institute of Cardiological Research, Saratov State Medical University, Saratov, Russia *Corresponding author E-mail: kiselev@cardio-it.ru.

The higher education is associated with stress 1, 2 , especially in freshmen 3,4 , against the background of memory, attention, thought processes, and changes in living conditions. It is well known that stress leads to changes in nervous system functions and behavior 5 , as well as to endocrine, cardiovascular, and psychosomatic disorders 6,7 .
The functional state of the cardiovascular system, evaluated by the heart rate variability (HRV) parameters, may be considered an indicator of the regulatory system activity in human organism 8 . The index of regulatory system activity (IRSA) was proposed in early 1980s to assess the functional state of human organism [9][10][11][12] and turned out to be sufficiently effective for differentiating the levels of the regulatory system strain and assessing the adaptive potential of a human body. Later on, its computation algorithm underwent some improvements 11,12 . This index uses a specific algorithm involving statistical indicators, histogram data and interval spectral analysis calculated. This indicator is often used by Russian authors [13][14][15] and is actively employed in medical computer appliances, developed in the RF. However, it has been successfully used by some foreign research teams as well 16,17 .
The association of mental activity parameters of college freshmen with IRSA levels was not studied before. Hence the objective of our study was to compare the parameters of mental functions in freshmen with different IRSA levels.

Materials and Methods subjects
The study included 150 healthy young men 19.0 (19.0, 20.0) years of age (data presented as median with lower and upper quartiles). The criteria for inclusion into the study were as follows: 1) written consent to participate in the study, 2) absence of chronic somatic and mental pathology in anamnesis, 3) lack of traumatic brain injuries and other nervous disorders, 4) verification of relative health at the time of the survey, and 5) male gender. Exclusion criteria involved refusal of examined subjects to participate in the study, positive responses to the second and third inclusion criteria, and confirmation of acute illness at the time of examination.

ethical approval
The design of our study was approved in 2019 by the Ethics Committee of the Saratov State Medical University (Saratov, Russia). Informed consent was obtained from all participants. All procedures performed in the studies, involving human participants, were in accordance with the ethical standards of the institutional research committee, as well as with the 1964 Declaration of Helsinki and its later amendments, or comparable ethical standards. evaluating the functional state based on irsa values IRSA was calculated using the computer appliance VNS-Spectrum (Neurosoft LLC, Ivanovo, Russia; https://neurosoft.com/ru/catalog/ hrv-analysis/VNS-spectrum). Contemporary IRSA algorithm incorporates the following five criteria 11,12 Criterion A (Total regulatory effect) is computed from the heart rate (HR); Criterion B (Overall regulatory activity) is computed based on total power of HRV spectrum (TP) and SDNN, i.e. standard deviation of normal-to-normal RRintervals, where R is the peak of a QRS complex on an electrocardiogram (heartbeat); Criterion C (Autonomic balance) is computed on the basis of the straining index (SI) values, square root from the sum of squared differences of sequen tial normal RR-intervals (root mean square of the successive differences, or RMSSD), power in a highfrequency range (0.15-0.4 Hz) of HRV spectrum (HF), and index of centralization (IC); Criterion D (Vasomotor center control of vascular tone) is computed from the power in a low-frequency range (0.04-0.15 Hz) of HRV spectrum (LF); Criterion E (Activity of the cardiovascular subcortex nervous centers, or suprasegmental regulation) is computed from the power in a very-low-frequency range (less than 0.04 Hz) of HRV spectrum (VLF).
The IRSA value is calculated as the sum of the scores (their absolute values) of the above five criteria. IRSA values ??are expressed in numbers between 1 and 10. Depending on the IRSA values, four functional states of a study subject's organism are distinguished 11 : i) a state of norm, or a state of satisfactory adaptation (IRSA = 1-3); ii) a state of functional strain (IRSA = 4-5); iii) a state of over strain, or a state of unsatisfactory adaptation (IRSA = 6-7); and iv) a state of regulatory system depletion, or an adaptation failure (IRSA = 8-10).
To measure an information stress impact in students as the basis for development of psychosomatic disorders, we used the College Schedule of Recent Experience-Modified (CSRE-M) 18,19 .
To assess the index of psychological stress, the questionnaire for evaluating neuropsychiatric stress by T.A. Nemchin [20] (Supplement A) was used.
To determine an effectiveness of mental operations of classification, analysis and an ability to identify the essential features of objects, we employed a verbal version of the Exclusion of Irrelevant Items technique (Supplement B), which is very popular among Russian psychologists.

statistical analysis
We reported continuous variables as medians with lower and upper quartiles -Me (LQ, UQ). Binary variables were presented by us as frequencies and percentages -n (%). We applied the Shapiro-Wilk test to check whether the values were normally distributed. Since most variables were not normally distributed, further analysis was carried out using nonparametric statistical methods. We used the Mann-Whitney test to compare the values of continuous variables between the groups of study subjects. The results were considered statistically significant if the p-value was less than 0.05.

results
The results of assessing the level of emotional strain, the index of psychological stress, and effectiveness of mental operations of classification and analysis in freshmen with different IRSA scores are presented in the Table  1. Statistically significant differences from Group 1 in the level of emotional strain and the index of psychological stress were found in Groups 3 and 4. Group 4 exhibited significantly different effectiveness of mental operations of classification and analysis, compared with the Group 1.

discussion
We discovered that male freshmen in all groups, differing by their IRSA scores, had a high degree of emotional strain with a high risk of developing psychosomatic disorders, while those with unsatisfactory adaptation (Group 3) and adaptation failure (Group 4) had a significant increase in the average values of their emotional strain and an increase in psychological stress to a moderate level. All subjects exhibited a high level of effectiveness of mental operations on comparison and generalization. However, students with a failure of adaptive mechanisms (Group 4) demonstrated a significant decrease in the effectiveness of their mental processes.
The prospects for using HRV indicators to assess the resilience of mental processes have already been discussed in the context of modern scientific data 21 . At the same time, HRV indices of vagal activity (specifically, HF, RMSSD, along with a widely used measure of HRV -pNN50) are of particular importance for adults. Changes in HRV parameters are also known in patients with depressive mental disorders 22 . Analysis of the association of mental status with HRV indicators has been very actively studied among young people, including students [23][24][25][26] . Summarizing the published data, we should point out that individuals with different states of their mental functions have characteristic differences in HRV indicators, although the research data are somewhat different. Difficulties in studying such relationships could The statistical significance (p-values) of paired differences among indicators in Groups 2-4 with Group 1 is presented be due to the fact that different HRV assessments among people with certain mental status features are often studied simultaneously. In our research, we attempted to go the opposite way: first, to divide the subjects according to their HRV specificities, and then to compare obtained characteristics of mental status among the groups. It should be noted that for such task, an integral HRV indicator is required, taking into account all its properties as much as possible; in our opinion, IRSA can be considered a suitable indicator for this purpose. As a result, the association of the autonomic regulation of heart function with properties of mental status was reconfirmed, and potentially important additional information was obtained.

conclusion
We conclude that all male freshmen with different levels of regulatory system activity in our study have high rates of psychological stress and emotional strain, which ultimately leads to a significant decrease in the effectiveness of their mental operations and adaptation failure.

Conflict of interest
All authors declare no potential conflict of interest.