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4DOI 10.24412/2709-1201-2024-150-156 UDC 616.89 - 072.8 + 577.7+ 611.86.
INFLUENCE OF THE NEW CORONAVIRUS INFECTION COVID-19 ON THE SENSE OF SMELL IN PEOPLE OF ELDERLY AGES
BAGIROVA FARIDA MAMED SADIKH
Candidate of Biological Science, Associate Professor of the Institute of Physiology named after Academician Abdullah Garayev of the Ministry of Science and Education
of the Republic of Azerbaijan
MEDJIDOVA MESMEHANUM ABBAS
Candidate of Medical Sciences, director of the Gerontological Center of Baku
MURSALOVA AYTYAN AYAZ Head of the Neurological Department of the Gerontological Center of Baku
QUSEYNOVA QULNARA QUSEYN AGA
Candidate of Biological Sciences, senior teacher of Azerbaijan State Academy of Physical
Education and Sport
SAFAROVA SEVINJ QUSEYN AGA
Teacher of Azerbaijan State Academy of Physical Education and Sport
Abstract. This article is devoted to one of the most urgent problem today, modern biology and medicine - the new coronavirus infection COVID-19 with its effect on the sense of smell. We studied the psychoemotional and psychophysiological state of elderly (60-74 years old) people. An analysis of both the literature and the data obtained by us by survey and questionnaire for the period of the study of this new coronavirus infection was presented COVID-19. There was a violation of smell in people of elderly ages. It has been shown that the new coronavirus infection COVID-19 in some cases leads to hypo- or anosmia. It has been established that with COVID-19, anosmia can be one of the first and leading symptoms, since a complete or partial loss of smell sharply reduces the quality of life, up to its threat. Lesion of the olfactory epithelium, mucosal edema contributes to the difficulty of the effect of odorants on the neuroepithelium. Generalizing analysis shows that the restoration of smell in elderly people occurs in different ways. We noted cases of lack of restoration of smell even 2-3 years after infection.
Key words: COVID-19, elderly people, psychoemotional state, anosmia, hyposmia, restoration of smell.
Anosmia suddenly developing in the first wave of COVID-19 [17] was the only symptom of the disease even before the appearance of fever, shortness of breath, cough, intestinal disorders. Since the virus spreads mainly by airborne droplets, according to the physiological movement of air flows in the nasal cavity, the infected inhaled air first enters the olfactory zone, choosing Bowman glands as a target. The secretion of the glands, which ensures the perception of odorants, becomes incapable of differentiating odors.
It is known that the causative agent of coronavirus infection is the SARS-CoV-2 virus, the high virulence of which is explained by the fact that when binding to the angiotensin-converting enzyme 2, which is the virus transporter into the host cell, a decrease in the minimum free energy is required.
In the literature, it has been shown that the COVID-19 virus uses the angiotensin-converting enzyme receptor 2 to obtain entry into the cell. This fact increases interest in studying the expression of the angiotensin-converting enzyme 2 not only in the disturbance of the senses, but
also in the nervous tissue as a whole and in assessing the ongoing damage to the peripheral system and the CNS. Severe headache and increased BP, often not corrected by antihypertensive drugs, were noted in 52% of patients of older age groups with olfactory dysfunction. Anosmia or hyposmia persisted for more than 5 days, but most patients recovered, by day 30, the sense of smell was restored in all observed patients. As a rule, headache disappeared by this period, which can be regarded as a favorable prognosis for the restoration of olfactory function and the CNS as a whole
In 10 out of 90 tested patients with a new coronavirus infection, an abnormal chemosensory function was demonstrated during objective olfactory testing, despite a normal subjective sense of smell [29]. At follow-up, 43% (44/102) of subjects showed symptomatic improvement in smell and restoration of intestinal function [28]. This can be explained by the now known fact that the virus in the patient can be in the small and large intestine, feces, accompany the clinical picture of diarrhea, nausea, headaches and others, essentially excluding the respiratory route of infection. The spread of the virus along preformed pathways from the olfactory zone to the CNS with mediated damage to other organs and systems is not excluded. The fact that in patients a frequent symptom is a violation of the sense of smell both in severe cases and in non-symptomatic or low-symptomatic cases can definitely serve as a basis for a detailed study of the "behavior" of the coronavirus in the olfactory zone.
It is already known that COVID-19 can have neurological manifestations, which is due to the penetration of SARS-CoV-2 into the brain by synaptic contact through the olfactory tract and hematogenically.
Endothelial dysfunction, endothelitis, vasculitis, encephalitis, encephalomyelitis are observed. When infection penetrates through the circumventricular organs, olfactory nerves, olfactory cortex, hippocampus, hypothalamus are primarily affected. Changes include acute hypoxic and ischemic alterations. At the autopsy of patients who died from a new coronavirus infection, astrogliosis, microglial activation and infiltration by cytotoxic T-lymphocytes were detected. The main location of the lesion concerns the brainstem, cerebellum and meningeal membranes. All the above indicates the neurotropicity of COVID-19, which can serve as an explanation for cognitive impairment and psychoemotional disorders [1]. The new coronavirus infection affects people of all age groups, but the elderly remain the most susceptible [2].
Comorbidity of cognitive impairment and severe course of SARS-CoV-2 (decreased attention level, impaired executive function) was revealed. A number of studies have identified the relationship of cognitive disorders with olfactory impairment. The course is aggravated by the age factor, the degree of involvement of the lung tissue and the initial level of depression and anxiety.
The organic nature of cognitive impairment due to damage to the neurons of the trunk, hippocampus, hypothalamus, cortex of the frontal lobes is suggested by pathomorphological studies. A study conducted by A.T. Pajo and co-authors demonstrated neuropathological features in the hippocampus (CA1 zone), parahippocampal gyrus, Purkinje cells in the cerebellar cortex, neocortex cells, brain stem neurons, olfactory bulb, chiasma, neostriatum [17].
The work of S.P. Bordovsky and co-authors and M. Almeria and co-authors [1, 4] made it possible to identify the connection between the presence of headache, hypo- or anosmia, taste disorder and cognitive impairment, such as memory decline, attention, and control functions. The duration of cognitive disorders is variable, there is a tendency to a prolonged presence of symptoms, but it is more often reversible.
In such a group of patients, the identified processes affecting the brain influenced the direction of anosmia therapy. The drugs include the NMDA receptor antagonist Acatinol memantine [17,23].
According to Y. Lee et al., J.R. Lechien et al., acute anosmia and/or ageusia were observed in 11-15% of patients (more often in women) at an early stage of COVID-19 and in 16-44% of patients with asymptomatic or mild disease [22, 23]. Olfactory dysfunction, according to A.R. Sedaghat et al., according to the subjective feelings of patients with covid infection, can reach up to
[9, 11].
60% of cases. Objective olfactory function testing by these same authors shows an even higher prevalence of anosmia. Olfactory dysfunction, according to the authors, is accompanied by a taste disorder in almost 25% of patients with COVID-19. The authors propose to consider the unexpected appearance of olfactory dysfunction and ageusia as the first symptom of the disease. Olfactory dysfunction in COVID-19 in most cases is stopped within a few weeks [30].
According to X.Meng et al., anosmia can occur independently without other clinical manifestations of the disease and be the main objective criterion in the diagnosis of a new coronavirus infection [24].
According to some hypotheses, the receptor capacity of odor binding depends on the size of the odor molecule [6,14].
A.Printza et al also regard anosmia as a potential screening syndrome that may contribute to the decision to test suspicious cases and comply with quarantine instructions. Olfactory and/or taste disorders can be early or isolated symptoms of severe acute respiratory syndrome of type 2 coronavirus infection and can serve as an additional screening criterion for detecting patients in the early stages of infection.
Pathogenetically, covid-associated anosmia is unclear. Presumably, anosmia and the positive effect of the use of essential oils can be explained by the restoration of the composition of the secretion of the Bowman glands, an increase in the regenerative ability of olfactory neurons in response to continued stimulation by odorants.
A number of authors have shown that heavy molecules can bind to a limited range of olfactory receptors [7]. However, no dramatic difference in change in olfactory characteristics can be attributed to the molecular weight of odors used to train the sense of smell. An alternative way of activating more olfactory receptors may refer to a model proposed by A. Altundag et al. In this case, the use of more different odors (rather than a few) would increase olfactory abilities due to cognitive changes leading to improved perception of odors [14]. The authors, reflecting on further olfactory training strategies, consider it necessary to take into account the use of mixed odors containing odorous compounds perceived by the olfactory and trigeminal nerves, since the interaction of these two systems has already been well investigated [7, 19]. The physiological mechanism of smell restoration is not fully known [7].
There are no valid objective tests to assess olfactory function, which makes it difficult to determine the effectiveness of treatment. The proposed Sniffin Sticks (Burghardt, "Wedel," Germany) tests are a psychophysical test developed by Hummel in 1997 and validated in several European countries. Such testing allows only a semiobjective assessment of the patient's sense of smell using three indicators (threshold test, identification test and discrimination test) [31].
To train impaired olfactory function in the postcovid period, tests that were proposed long before the epidemic can be used. Thus, T. Hummel and co-authors for the examination of patients with impaired smell raised the question of the possibility of improving olfactory function in anosmia from "training" with aromas from a subjective point of view. It has been suggested that it is possible to realize in patients with postcoid anosmia that olfactory training should lead to both an increase in sensitivity to odors and an overall increase in olfactory function [16]. Olfactory training, according to J. Mullol et al., is recommended when the sense of smell is not restored in 1 month, but can be started earlier [25].
The method of stimulation of smell was first used by T. Hummel et al in 2009 in patients with post-viral, post-traumatic and idiopathic anosmia. According to T. Hummel and co-authors, olfactory training is an independent regular (6-8 workouts per day) inhalation of aromatic odorants by the nose. Odorant sets may be formulated arbitrarily. Patients of the main group were trained twice a day with a set of essential oils (rose, eucalyptus, lemon, cloves). After 12 weeks there was an improvement in smell (Sniffin Sticks test) in the main group, while no changes were noted in the control group. Subsequently, a number of studies were carried out, in particular, the method gave a positive result in Parkinson's disease. There was a higher efficacy of prolonged treatment (32 weeks), as well as with the use of higher concentrations of odorants compared to low ones [16, 18,
21]. In other works, the effectiveness of a 9-month olfactory training was shown: four odorants were used - oils of rose, eucalyptus, lemon, cloves, odorants were changed every 3 months for oils of tea tree, bergamot, rosemary, gardenia [11, 16, 23, 27].
Apparently, olfactory training, consisting of daily ultra-threshold odor exposure for 12 weeks, [15, 27], improves olfactory function, but a longer period (30-32 weeks) of training using known essential oils, a combination of essential balm, vinegar, alcohol and pink perfumes is necessary for a stable effect.
Repeated short-term exposure to odors has been found to improve the sense of smell in patients with acquired olfactory dysfunction. Restoration or improvement of smell after systematic olfactory training in the form of multiple short-term odor exposure has been shown in olfactory disorders caused by upper respiratory tract infection, skull injury of idiopathic origin[12, 16, 20]. Apparently, such an improvement is the result of stimulated neuronal plasticity in the experiment [34, 36], as well as in humans [35, 36], suggesting changes at the level of olfactory receptor gene expression or differentiation of olfactory receptor neurons from basal cells.
F.Fleiner et al concluded that the time to smell recovery and odor identification can be enhanced by adding a topical corticosteroid to the daily olfactory training program [13]. The lack of effect of topical corticosteroids in anosmia, which was most often transient, was noted in the postcoid period. The question of prescribing topical glucocorticoids for covid remains open, especially in patients suffering from bronchial asthma, allergic rhinitis, in whom topical corticosteroid therapy is basic [8, 31].
Intranasal corticosteroids should remain the standard treatment for chronic rhinosinusitis in patients with COVID-19 infection, according to L.Klimek et al. Surgical treatment during this period should be minimized, except for patients with a complicated course of the disease and for those who do not have other treatment options. The authors believe that patients with chronic rhinosinusitis should avoid systemic corticosteroids during the period of covid infection. As for the prescription of biologically active drugs, it should be temporarily interrupted during the course of COVID-19 infection. Along with this, there are observations about the positive use of biologically active drugs in patients who have undergone covid infection to relieve the existing disorders of the vestibular analyzer, restore muscle tone [4, 21].
According to modern literature, in patients with COVID-19 infection, the use of intranasal corticosteroids (including spray) can be continued in allergic rhinitis at the recommended dose. The opinions of scientists differ, and if some [20] consider intranasal corticosteroids a mandatory agent for anosmia and propose their use as the main drug, then others for post-Covid anosmia and ageusia exclude the prescription of intranasal corticosteroids and, moreover, have expanded contraindications to washing with saline solution, since this can contribute to the spread of the virus
In general, the predictions and methods of treatment of disorders of smell after covid infection are revised and accompanied by empirical experience [18].
The olfactory analyzer function remains completely unexplored. A number of authors show a lower olfactory sensitivity to severe odorant molecules in elderly people [32] and a higher frequency of specific anosmia [26, 28]. When examining patients with impaired smell, it is important to be aware of differential diagnostics with other pathological conditions, despite the high prevalence of COVID-19. In patients of the older age group, special attention is paid to the state of cognitive function and psychoemotional disorders.
Dementia onset and progression may be associated with olfactory symptoms. Alzheimer's disease, vascular disorders, dementia with Lewy bodies, Pick's disease, neurosurgical diseases should be excluded in the presence of symptoms of olfactory function disorder. COVID-19 is associated with some neurological diseases and complications, such as encephalopathy, seizures, stroke, cranial nerve paralysis, peripheral neuropathy and myopathy.
Conclusions
[4, 36].
It has been established that with COVID-19, anosmia can be one of the first and leading symptoms, since a complete or partial loss of smell sharply reduces the quality of life, up to its threat. There was a violation of smell in people of elderly age. It has been shown that the new coronavirus infection COVID-19 in some cases leads to hypo- or anosmia.
Generalizing analysis shows that the restoration of smell in all people occurs in different ways. We also noted isolated cases of lack of restoration of smell even 2 -3 years after infection.
In patients with older age groups with covid infection, impaired smell is a frequent and important diagnostic sign. Considering the elderly age of patients, differential diagnosis of olfactory dysfunction detected in COVID-19 with possibly existing neurological pathology (Alzheimer's disease, Pick's disease, post-traumatic encephalopathy, atherosclerosis of the cerebral vessels) is necessary. Olfactory training (aromatotherapy), B vitamins and physiotherapy (endonasal electrophoresis) are recommended as therapy for hyperosmia, parosmia and anosmia.
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