Since its outbreak, in December, 2019, in the Chinese city of Wuhan, coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into an ongoing global pandemic. Due to the novel antigenic properties of this virus, the world population could not develop immunity effectively and this led to the subsequent spread of COVID-19. This caused an unprecedented emergency situation with significant negative effects on health and well-being both on an individual and societal level. Apart from health, economic and social consequences, the impact of this pandemic on mental health is increasingly being reported in the scientific literature. The present review aimed to provide a comprehensive discussion of the possible neurological and neuropsychiatric manifestations of SARS-CoV-2, together with the related underlying molecular pathways. In addition, the present review focused on populations which are at a higher risk of developing psychiatric disturbances due to the COVID-19 pandemic and discussed possible routes of clinical management and therapeutics to minimize the burden associated with psychiatric disorders. Moreover, research findings exploring the prevalence of COVID-19-related post-traumatic stress disorder (PTSD) symptoms across vulnerable groups, including children, adolescents and COVID-19 survivors are presented, with particular emphasis on those with severe disease who required hospitalization and/or intensive care unit admission. Based on the available literature, the identification of potential determinants associated with PTSD across the different populations is underlined. Lessons learnt from the pandemics across the globe together with the ongoing research on COVID-19 and its impact on mental health, highlight the utmost importance for evidence-based, proactive and targeted interventions in high-risk groups aiming to mitigate the risks and manage vulnerabilities.

There is a growing body of evidence highlighting the role of gut microbiota as a biological basis of psychiatric disorders. The existing literature suggest that cognitive and emotional activities can be influenced by microbes through the microbiota–gut–brain axis and implies an association between alterations in the gut microbiome and several psychiatric conditions, such as autism, depression, bipolar disorder and psychosis. The aim of this review is to summarise recent findings and provide concise updates on the latest progress of the role of gut microbiota in the development and maintenance of psychiatric symptoms in schizophrenia and the first episode of psychosis. Despite the lack of consistent findings in regard to specific microbiome changes related to psychosis, the emerging literature reports significant differences in the gut microbiome of schizophrenic subjects compared to healthy controls and increasingly outlines the significance of an altered microbiome composition in the pathogenesis, development, symptom severity and prognosis of psychosis. Further human studies are, however, required, which should focus on identifying the drivers of microbiota changes in psychosis and establish the direction of causality between psychosis and microbiome alterations.