**3. Neuropsychiatric and neurocognitive effects of the disease in the acute and chronic periods and its clinical manifestations**

During the COVID-19 pandemic, social restrictions and the fear of contact with a COVID-19 patient have created a serious social panic. This is a cause for many psychological disorders [11, 23]. Anxiety and depression are the most common psychiatric disorders in this process [24]. In some studies, it has been demonstrated that the incidence of post-traumatic stress disorder (PTSD) is between 7 and 53.8% during the pandemic process [25]. Especially in elderly patients, cognitive dysfunction is associated with social isolation and psychological disorder [26]. In a recent population-based study, the effect of psychological stressors on the general cognitive functions of the population was evaluated. The results demonstrated that these factors cause cognitive dysfunction. In addition, it has been demonstrated that the psychological disorders associated with the pandemic are induced by anxiety and depression [27].

Cognitive disorders after viral infections have a complex presentation [12, 28]. There are some publications about neurocognitive effects of the COVID-19 pandemic. Acute impairment in neurocognitive functions during the COVID-19 disease is associated with metabolic disorder. Other neuropathological mechanisms are

neurotropism of SARS-CoV-2, mechanical ventilation and adverse effect of neurosedative treatments [29].

In a study during the initial period of the pandemic, many neurological symptoms have been reported in patients with COVID-19. Dizziness, headache and neurocognitive deficits were detected in 24.8% of the patients [7]. In a study reported from the UK, behavioural and cognitive impairments were detected in 31% of the patients. Major neurocognitive disorders were determined in approximately 5% of total patients. Some cases of acute viral encephalitis have been reported during or after COVID-19. Transient or persistent neurocognitive disorders were determined in patients with encephalitis [3, 30]. These symptoms are called dysexecutive syndrome. Approximately 25% of COVID-19 patients presenting with ARDS had dysexecutive syndrome. Executive dysfunction predominates in these patients [8, 31]. It has been reported that neurocognitive disorder symptoms are more common in the elderly patients with severe respiratory/systemic symptoms [3]. Many mental disorders have been reported in the acute or chronic period of COVID-19 disease. In addition, post-infection cognitive disorders continue with long-term inattention and memory problems.

The long-term effects of COVID-19 disease were investigated in some studies. In a study by Woo et al., cognitive functions of COVID-19 patients were evaluated after being discharged from the intensive care unit. A lower cognitive function score was detected in the patients. More than one cognitive disorder, such as inattention (50%) and memory disorders (44.4%) was detected [32]. Lu et al. evaluated 60 patients during the early stage of SARS-CoV-2 infection and at a 3-month follow-up. Cognitive impairment increased during the process in this study [33].
