Diagnosis of insomnia disorders in chronic mercury intoxication

Introduction. It is now known that insomnia has a high comorbidity with various somatic and neurological diseases. In patients with chronic mercury intoxication, sleep disturbances are significantly more common than in the general population.

The purpose of the study is to identify the most significant diagnostic criteria for insomnia disorders in patients with occupational chronic mercury intoxication.

Materials and methods. The study involved thirty patients with occupational chronic mercury intoxication (CMI), who worked at Usolekhimprom LLC, whose mean age was 56±0.71 years, and 30 patients in the comparison group, whose mean age was 54±0.66 years, who complained of disorders sleep without contact with toxic production factors. A neurophysiological (polysnography), psychological (anxiety and depression level) study was carried out, as well as a quantitative determination of some neurotransmitters in the blood.

Results. Polygraphic registration of biopotentials in CMI patients revealed an increase in the time to fall asleep (35.0 (30.5–47.0) min; a decrease in the duration of sleep (total sleep time, 339.5 (305.0–374.0) min); increase in the number of activations (2.9 (1.9–3.6)% of RVO) and total wakefulness during sleep (18.7 (11.3–23.5)%); decrease in the number of sleep cycles (3.0 (2.0–4.0)); decreased sleep efficiency index (70.95 (60.7–78.2)%) and integrative sleep quality index — IISQ (17.8 (13.4–27.5)), in the control group, an increase in total wakefulness within sleep (12.2 (8.4–18.6)%); an increase in the latent period of the REM stage (93.0 (72.0–117.0) min); decrease in the number of sleep cycles (3.0 (3.0–4.0)); decrease in the sleep efficiency index (78.4 (73.9–81.5)%) and the integrative sleep quality index — IISQ ( 14.1 (10.9–20.6)). dopamine levels in the blood, compared with the control group.

Limitations of the obtained results. The results cannot be generalized to workers as the group included only men.

Conclusion. A certain set of diagnostic criteria can be used for the differential diagnosis of insomnia in occupational CMI.

Compliance with ethical standards. In accordance with the principles of the Declaration of Helsinki of the World Association “Ethical principles for conducting scientific medical research involving humans” (as amended in 2008), “Rules of clinical practice in the Russian Federation” (approved by the Order of the Ministry of Health of the Russian Federation of 19.06.2003 No. 266) studies were conducted with the informed consent of the subjects, approved in the prescribed manner by the Committee on Biomedical Ethics. The research did not infringe on the rights, did not endanger the well-being of the subjects, did not harm their health.

Patient consent. Each participant of the study (or his/her legal representative) gave informed voluntary written consent to participate in the study and publish personal medical information in an impersonal form in the journal "Gigiena i Sanitariya (Hygiene and Sanitation, Russian journal)".

Contribution:
Korchuganova E.N. — the concept and design of the study, the collection of material and data processing, writing the text, responsibility for the integrity of all parts of the article;
Katamanova E.V. — concept and design of the study, statistical processing, text writing, design and editing of the article;
Kudaeva I.V. — collection and processing of data, design and editing of the article;
Slivnitsyna N.V. — the concept and design of the study, data collection and processing, writing texts, design and editing of the article.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version. 

Conflict of interest. The authors declare no conflict of interest. 

Acknowledgment. This work was carried out within the framework of state assignment.

Received: August 30, 2022 / Accepted: October 3, 2022 / Published: November 30, 2022