Neurocognitive markers of combat-related psychological disorders: a comparative cross-sectional study

INTRODUCTION. Armed conflict has a serious impact on the mental health of combatants. Cognitive and sensorimotor impairments in this patient group are being studied because they significantly affect combat effectiveness. The study opens up new opportunities for understanding the pathophysiological mechanisms of mental disorders, developing objective diagnostic criteria, and creating personalized approaches to therapy.

OBJECTIVE. To study the peculiarities of the functioning of individual cognitive and sensorimotor systems in combatants with combat-related mental disorders.

MATERIALS AND METHODS. The study involved 94 male military personnel divided into two groups: a group with combat-related mental disorders (CRMD) (n=53) and a comparison group (n=41) of healthy military personnel. Validated psychometric scales were used for additional diagnosis of the severity of mental disorder symptoms: the Hospital Anxiety and Depression Scale (HADS), the subjective Asthenia Rating Scale (MFI), which includes subscales for general asthenia, decreased activity, decreased motivation, and physical and mental asthenia; the Clinical Assessment of Posttraumatic Stress Disorder Scale (CAPS), the Hamilton Anxiety Rating Scale (HAMA), and the Impact of Event Scale-Revised (IES-R). To identify neurophysiological correlates of sensorimotor and cognitive functions, the Dexterity and Pursuit Rotor techniques were used, presented using the Psychology Experiment Building Language (PEBL version 2.0) software. The functional state of the central nervous system was assessed using the Encephalan-NEXT hardware and software complex. The data were processed using StatSoft Statistica 12.0 software. The Mann-Whitney U test was used to determine intergroup and intragroup differences, with differences considered statistically significant at p<0.05. Correlations were calculated using Spearman’s criterion.

RESULTS. An analysis of cognitive-motor functions in individuals with combat-related mental disorders (CRMD) revealed complex impairments in higher mental functions, including motor dysfunction and reduced learning ability. The data obtained confirm the hypothesis of impaired movement accuracy and cognitive control of motor activity in the study group. The analysis of the results of the Dexterity test showed that subjects with CRMD took significantly longer to complete the task than the control group, indicating a marked decrease in the speed of sensorimotor reactions. In addition, the CRMD group showed a statistically significant increase in the number of corrective movements relative to the control indicators, reflecting impairments in the accuracy of motor acts. Correlation analysis showed that the test time and the number of corrective movements were directly related to the severity of reduced activity on the subjective asthenia assessment scale (MFI), impaired movement accuracy was associated with physical asthenia on the same scale, as well as with symptoms of increased excitability on the CAPS scale and the severity of anxiety symptoms on the Hamilton Anxiety Scale.

DISCUSSION. Research shows that the normal functioning of sensorimotor systems and cognitive control is ensured by the complex interaction of cortical and subcortical structures. In particular, the initiation of movements depends on the activity of the supplementary motor area (SMA) and the pre-SMA zone, while their inhibition is regulated by the right inferior frontal gyrus (rIFG) and the subthalamic nucleus (STN) via the “hyperdirect” pathway of the basal ganglia. Cognitive aspects of control, including suppression of unwanted responses and monitoring of action effectiveness, are performed by the anterior cingulate cortex (ACC) and dorsomedial prefrontal cortex (dlPFC). In patients with BPR, the identified impairments in movement accuracy and reduced learning ability may be associated with dysfunction of these neural networks. In particular, deficits in inhibitory control may reflect disturbances in the functioning of the rIFG and STN, while difficulties in learning motor skills may reflect possible dysfunction of the SMA and associated basal ganglia. Neurochemical imbalances, particularly in the GABAergic and noradrenergic systems, may also contribute to the observed impairments, explaining both motor and cognitive deficits. Individuals with combat-related mental disorders spent significantly more time on the tests than healthy individuals and also performed a greater number of both target and corrective movements. The data obtained on the decrease in motor coordination in patients with CRMD are consistent with the results of previous studies, where similar disorders were explained by dysfunction of the prefrontal cortex and amygdala. It can be assumed that the impairments in motor tests identified in the CRMD group are associated not only with psychological factors (e.g., increased anxiety) but also with neurobiological changes affecting cortical-subcortical interactions.

CONCLUSION. Individuals with combat-related mental disorders (CRMD) have been found to have reduced movement accuracy and slowed sensorimotor reactions associated with increased fatigue and reduced cognitive control over movements, which is critically important for survival in combat conditions. The objective markers identified allow the use of the Pursuit Rotor (assessment of visual-motor coordination) and Dexterity (testing of agility and reaction speed) methods in the comprehensive diagnosis of combat mental disorders, and also indicate new targets for the development of medical and psychological rehabilitation measures.

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