key: cord-0991410-85vbylct
authors: Fleischmann, Eva; Dalkner, Nina; Fellendorf, Frederike T; Reininghaus, Eva Z
title: Psychological impact of the COVID-19 pandemic on individuals with serious mental disorders: A systematic review of the literature
date: 2021-12-19
journal: World J Psychiatry
DOI: 10.5498/wjp.v11.i12.1387
sha: cdd0484a1eb08e886b1a31ba1836c645d3679851
doc_id: 991410
cord_uid: 85vbylct

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is having a great impact on individuals from all over the world, particularly on individuals with mental disorders. Several studies found more pronounced psychiatric symptoms, notably symptoms of depression and anxiety. AIM: To assess the situation of patients with serious mental illness (SMI: Affective disorders and schizophrenia) regarding their mental health outcome during the pandemic. METHODS: A systematic search using the databases PubMed and MEDLINE was conducted, employing the key words “COVID-19”, “SARS-CoV-2”, “psychiatric/mental disorder/illness”, “affective/mood disorder”, “bipolar disorder”, “(major) depression”, “schizoaffective disorder”, and “schizophrenia”. Studies that had been published up until January 9, 2021 were included. Information of studies in languages other than English and German was mostly taken from their English abstracts. RESULTS: The literature search concluded in the finding of 36 studies containing relevant clinical data. A general impairment of the mental health of individuals with SMI could be detected, particularly in individuals with affective disorders, as compared to those with schizophrenia. Compared to healthy controls, symptoms of anxiety, depression, and stress were more pronounced in individuals with SMI. Relevant factors found that impacted their mental health were age, resilience, and socioeconomic environment, especially the shortage of mental health services, lack of social support, and inadequate information about COVID-19. CONCLUSION: In light of these results, mental health services should be reinforced, notably the use of telemental health services. Furthermore, supplying individuals with SMI with adequate information about the COVID-19 pandemic and increasing their resilience is important. When researching the impact of the COVID-19 pandemic on individuals with SMI, standardization as well as follow-up studies are needed to enable better comparability and understanding.

The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), is an infectious airborne disease. Initially detected in Wuhan, China[1], in December 2019, it subsequently spread throughout the world and reached the status of a pandemic on March 11, 2020 [2] . In order to stop the propagation of the virus, lockdowns comprising measures of physical distancing, travel restrictions, and closure of public facilities were implemented in numerous countries worldwide [3] .

The mental condition of both healthy and mentally ill individuals has been affected by the COVID-19 pandemic and its reverberations: Anxiety, distress [4, 5] , fear of the disease[5], loneliness[6], post-traumatic stress symptoms [7] , and the prevalence of depression, anxiety, and suicidality [4, 8, 9] have been found to be higher in the general population as a consequence of COVID-19. In particular, the prevalence of depression has increased drastically[5,10,11], affecting up to a quarter of the population[12,13], compared to a prevalence of 6.8%-8.5% before the pandemic [10, 14] . This is comparable to previous pandemics: During the SARS epidemic in 2003[15] and the West Africa Ebola virus disease pandemic from 2013 to 2016 [16] , similar effects were observed. Furthermore, economic growth has been stunted, resulting in a rising percentage of unemployment, and thus adding additional distress [17] . The individual condition during the COVID-19 pandemic might have been influenced by personality, resilience [18, 19] , coping strategies, and socioeconomic environment [20] . In summary, the pandemic in its entirety has led to restrictions of personal rights, heightened emotional distress, and fear of an uncertain future, and may advance the development of mental health problems [17, 21] .

Individuals already suffering from psychiatric disorders face additional issues that may influence their mental health: Limited resources for medical and psychotherapeutic treatment [22, 23] and misinformation [22] have been an additional strain. Furthermore, an increase in social isolation and negative feelings might lead to a worsening of psychiatric symptoms and even illness exacerbation [24] [25] [26] . Literature shows conflicting results concerning the impact of the pandemic on the mental health of individuals with psychiatric disorders. On the one hand, symptoms of different mental disorders have been reported to be significantly higher in the wake of the pandemic [27] [28] [29] [30] [31] . On the other hand, there was little to no change in symptomatology found in other studies [25, [32] [33] [34] , showing that more research in this area of interest is necessary.

Individuals with serious mental illness (SMI), which comprise bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SZ), are an especially vulnerable group due to several risk factors [35] , such as severe psychiatric illness episodes, hospitalization [36] , a lower level of education [37] , and cognitive deficits [38] [39] [40] . Furthermore, problems when interacting with healthcare services, for instance difficulties adapting to the clinical environment [41] , might lead to a worsening of wellbeing. Post-traumatic stress symptoms have been on the rise in both individuals with mental illness [42] [43] [44] as well as the general population [45, 46] , thus we focused on these symptoms in the course of our search as well. The need for increased support of this particular group of individuals has been highlighted by numerous mental health researchers [26, 41, 47] .

The impact of COVID-19 on individuals with SMI has already been reviewed in June 2020, emphasizing the vulnerability of individuals with SMI and advocating for an increased focus on support for them [35] . Another review by Zhand and Joober [48] included 47 studies with the final search being completed in July 2020, however, the authors focused mainly on SZ spectrum disorders, not mentioning BD and MDD.

Furthermore, a systematic review by Barber et al[49] , from June 2020, was found. The search yielded four studies, which found that individuals with SMI might show a decline of mental health due to COVID-19-related governmental measures. Furthermore, they experienced increased psychological distress during the crisis.

In comparison with already existing reviews, the current one focuses on the mental health outcome of individuals with SMI in general, encompassing solely papers providing scientific data and including studies that were published at a later time.

The aim of this review is to further broaden the understanding of these complex disorders and thereby provide insight in how to support individuals with SMI during a global crisis. The following questions will be answered: How are individuals with SMI affected by the pandemic in comparison to healthy controls (HC) and what are the main psychiatric symptoms they are displaying? What are risk and protective factors that influence the severity of psychiatric symptoms and who is particularly vulnerable to these factors? How does symptomatology and frequency of illness episodes change during the course of the pandemic?

We conducted a review of literature for studies about COVID-19 and its impact on SMI in the databases PubMed and MEDLINE (Medical Literature Analysis and Retrieval System Online). The final search was conducted on January 9, 2021.

The main criterion was whether the studies analyzed samples of adults with preexisting psychiatric disorders (including BD, MDD, and SZ) regarding the impact of COVID-19 on their mental health. Primary outcome variables were those assessing psychological symptoms related to the pandemic.

The following Medical Subject Headings (MESH) search terms were applied in the database PubMed: "COVID-19" OR "SARS-CoV-2" [Title/Abstract] AND "psychiatric/mental disorder/illness" [Title/Abstract] OR "affective/mood disorder" [Title/Abstract] OR "bipolar disorder" [Title/Abstract] OR "(major) depression" [Title/Abstract] OR "schizoaffective disorder" [Title/Abstract] OR "schizophrenia" [Title/Abstract]. The relevance of the studies was determined by inspecting both the title and abstract of each study and the full text of several studies.

The following MESH search terms were applied in the database MEDLINE: "(covid19 or (covid(w)(2019 or 19)) or (corona(w)virus(w)disease(w)2019 or 19)) and (depression? or schizophren? or ptsd or (post(w)traumatic(w)stress))/ti" AND "(covid19 or (covid(w)(2019 or 19)) or (corona(w)virus(w)disease(w)2019 or 19)) and ((mental? or bipolar? or affectiv? or mood? or schizoaffect?)(w)(disorder? or illness?))/ti".

All languages were considered, with an emphasis on English and German literature. The relevance of the studies was determined by firstly inspecting the title of each study, then the abstract of a considerable portion of studies, and finally the full text of several studies.

Most individuals with SMI had a positive stance regarding measures for preventing COVID-19 [50, 51] , which was related to marriage and a higher level of education [51] . However, they were on average not as knowledgeable about COVID-19 and measures of prevention as HC [52, 53] . This reduced knowledge was associated with a low socioeconomic status, little education, and insufficient social support[52]. A higher belief in self-obtained COVID-19 information was related to both more [54, 55] and less [50] fear of the disease.

Compared with HC, individuals with SMI showed both more weight gain and frequent changes of sleep patterns [56] , however, duration of sleep was found to remain stable over time [57] . An increase in the number of substances used was detected [49, 52] . On average, individuals with SMI had fewer social contacts and did not go grocery shopping as often as before the pandemic [58] .

Individuals with SMI experienced more symptoms of depression, anxiety [56, 59, 60] , and stress [58] [59] [60] [61] [62] , partly due to loneliness and isolation [63] . Additional symptoms were elevated feelings of paranoia[59] and isolation [64] , self-harm, and suicidal ideation [65] . Fatigue was more prominent in those with a lower quality of life, which was related to severe depressive symptoms, insomnia, and pain [66] . While the majority of subjects with SMI reported to not be worried to get infected[52], they were on average more worried and fearful of contracting COVID-19 [58] and made less use of coping strategies than HC [56] . Individuals with SMI were generally more concerned about their financial situation than their own health, although this was found in a study conducted in August and September 2020 and not at the beginning of the pandemic [63] .

Individuals with affective disorders displayed both more voluntary self-isolation as well as stress related to it than in HC[67]. Among different disorders, levels of both perceived stress and related somatic complaints, as well as the latter's negative correlation with Clinical Global Impression (CGI), were highest in affective disorders [68] . Psychosocial distress was related to somatization, heightened alertness, psychic anxiety, and bad mood [69] . Other psychiatric manifestations included more symptoms of PTSD in patients with affective disorders than in HC[67], elevated feelings of vulnerability [63] , and sleeping problems [ Franchini et al [69] Italy, March 9-April 9, 2020 (during the lockdown)

Telephone-based, non-standardized survey of 101 euthymic patients with affective disorders; self-constructed questionnaires measuring emotional stressors and unpleasant lockdown experiences

The most frequently reported stress factor was frustration, which was significantly associated with unemployment, affecting two third of participants. Somatization, heightened alertness, psychic anxiety, and bad mood were related to unemployment as well. Associations between young age and anxiety, increased alertness, and monetary concerns could be found. The participants were satisfied with both the received supplies and information about the pandemic.

Non-standardized survey and therefore problems with generalization

Germany, 2 nd , and 3 rd week of March 2020 (during the lockdown)

Cross-sectional, standardized interviews with 196 individuals with mental illness (121 with AD, 41 with SZ, 21 with addictive disorder, and 13 with others); CGI More than half of participants were feeling more distressed than before the pandemic. Among individuals with affective disorders, 25% had sleeping problems.

González-Blanco et al [62] Spain Individuals with SMD reported higher levels of anxiety, depression, and stress than HC, but lower levels than individuals with CMD. After confounding variables were controlled, HC had less anxiety than individuals with SMD with no other differences in psychological factors. In individuals with SMD, anxiety was related to being single, suffering from COVID-19 symptoms, and increased stress levels. Many individuals with SMD (87.2%) could relish free time, however the percentage of HC who could, was higher (94%).

Selection bias and limited representativeness through selective access to digital resources, selfreported diagnoses and psychiatric symptoms, binary scales instead of Likert-type scales to assess behaviour Hamm et al [77] United States, April 1-23, 2020 (during the lockdown)

Semi-structured qualitative interviews with 73 older adults (age > 60) with MDD, comparison with pre-pandemic data; PHQ-9, PROMIS anxiety scale

Patients with MDD had a lower quality of life during the pandemic than before, but did not differ in depression, anxiety, and suicidal ideation symptoms. The disorders lead to differences in the CGI-score (M = 4.9, SD = 1.0), however, women had higher scores than men. Individuals with AD had the highest levels of both perceived stress and related somatic complaints. Higher CGI-scores were not associated with stress, but with stress-related somatic problems. These correlations were especially high in individuals with AD, and non-existent in individuals with SZ. The total relapse rate in the first trimester of the pandemic was 11% (n = 15 with SZ, n = 2 with BD), with the most frequently related influence being the interruption of antipsychotic medication (59%). However, the relapse rate did not differ from the rate in 2019. Individuals suffering from a relapse had been hospitalized at a more recent date than the individuals who remained stable. Very few patients (n = 2) attempted suicide or had suicidal thoughts during the pandemic.

Orhan et al [77] Netherlands Older patients with BD experienced less psychiatric symptoms during the pandemic compared to the baseline. Loneliness, not having children, passive coping style, low mastery, and neuroticism were associated with more psychiatric symptoms. All participants had on average fewer social contacts and did not go grocery shopping as often as before the pandemic. All individuals reported augmented levels of psychosocial stress, worried more about COVID-19, and were more fearful of contracting this illness than HC. Among individuals with depression, a quarter perceived an improvement, whereas 57.51% experienced a decrease of their mental health and 45.9% felt the need for more therapeutic support. Individuals with SZ reported mostly no or only slight changes in their mental health and did not find further therapeutic support to be necessary.

Small sample sizes of some groups, retrospective data assessment, selfidentification of mental disorders, individuals with mental illness and HC were not matched, possible gender bias, selection bias through method of recruitment, online assessment Riblet et al [78] United States, October 2019-March 2020 and April 23-May 4 (before and during the lockdown)

Longitudinal interviews of 11 veterans with SMI (5 with MDD, 5 with BD, and 1 with psychotic disorder), with three in-person interviews conducted before the stay-at-home order (baseline, 1-and 3-mo follow-up) and one telephone-based interview during the lockdown; baseline: MINI; later additions: Hopelessness, social connections, treatment engagement, and suicidal ideation There were no relevant changes concerning psychiatric symptoms during the pandemic compared to before. Few participants, who were significantly older (M = 71.7 yr) experienced an increase in symptomatology. Individuals with MDD were worried about their health and felt the need for more therapeutic support [58] . Numerous studies found more symptoms of depression [25, 42, 62, 70, 71] , anxiety [42, 62, 70, 72] , PTSD[42, 70, 72] , problems of sleep [70] [71] [72] , stress [62, 72] , suicidality, anger, impulsivity [72] , worry, loneliness [25] , and elevated substance consumption [71] in patients with MDD compared to either HC or measured symptoms before the pandemic. MDD was a predictor of severe distress [73] , which was connected to pandemic-related news [74] . Individuals with BD experienced more stress and depressive symptoms than those with MDD, with men having more severe depressive symptoms than women [75] .

Individuals with SZ reported to be less stressed during the COVID-19 pandemic than HC [76] and had the least amount of problems with a lack of information about COVID-19 in comparison to other psychiatric disorders [63] . However, they were apparently both more anxious and worried about the current situation and perceived the risk of being infected with COVID-19 as higher than HC [76] .

In comparison to individuals with SZ, patients with affective disorders were experiencing more feelings of vulnerability [63] . Furthermore, correlations between high CGI scores and stress-related somatic problems were especially increased in individuals with affective disorders, but could not be found in individuals with SZ[68]. Compared with BD and SZ, individuals with MDD were more worried about contracting the virus [64, 77] and had more concerns about service disruption [64] . Furthermore, they were more concerned about the future, suffered from more sleep problems, and exercised more [56] .

Regarding SMI in general, it was found that participants experiencing a worsening of psychiatric symptomatology were mainly elderly individuals [78] or had been hospitalized at a more recent date than the individuals who remained stable [36] . Nearly half of them were experiencing fatigue, which was related to a lower quality of life [66] . However, most of elderly individuals with SMI experienced less psychiatric symptoms [79], approved of the strict governmental measures, and were not afraid of being infected with COVID-19. A higher level of fear was associated with more symptoms of depression, anxiety, stress, and less frequent behavior concerning prevention in older patients with SMI [50] . One study investigating elderly individuals with MDD found a lower quality of life, but not increased symptoms of depression and anxiety [77] . On average, younger patients experienced worse overall health, were feeling more fearful, and had more difficulties adapting than older patients [63] . Additionally, young age was related to increased anxiety and financial concerns in individuals with affective disorders [69] .

Stress and distress in individuals with affective disorders were related to a longer duration of psychiatric illness, living alone during the lockdown, the habit of smoking, and frustration, which was associated with unemployment [69] . Especially younger individuals were concerned about pandemic-related consequences regarding their health[8] and socioeconomic status [67, 69] .

Concerning BD, symptoms of posttraumatic stress were related to anxiety and both work and financial difficulties in the wake of the pandemic. Acute manic symptoms seemed to be protective [42] . Loneliness, not having children, a passive coping style, low mastery, and neuroticism were associated with more psychiatric symptoms[79]. One study found that men had depressive symptoms to a greater extent than women [75] . Individuals with MDD and maladaptive daydreaming were feeling an elevated urge to daydream during the pandemic and had more problems controlling it [80] .

Individuals with SZ living in isolation due to a suspected COVID-19 infection were more stressed, anxious, depressed [81] , and had a worse quality of sleep than individuals with SZ who were not quarantined [82] . After the quarantine, this symptomatology continued [81] . When living in communal residencies, they were supported by both their cohabitants and mental health professionals, remained adherent to their treatment, and possessed knowledge about the consequences of COVID-19 [74] .

On the one hand, two studies found that psychiatric symptoms remained stable over time in individuals with SMI [57, 78] , while another one found that the relapse rate did not significantly increase during the pandemic [36] . On the other hand, several studies showed a third of individuals with SMI to exhibit symptoms indicative of a recurrence of their illness or a worsening of symptomatology [52, 63] .

Pinkham et al [57] found that affective symptoms remained stable over time. In contrast, other studies showed that individuals with affective disorders apparently displayed a high likelihood of psychological distress [73, 75] . In line with the latter finding, individuals with BD reported to have more psychiatric symptoms compared to the time before the pandemic in one study [75] .

The research on MDD was contradictory: On the one hand, few studies showed that individuals with MDD were resilient, mostly socially connected, and did not experience increased symptoms of depression, anxiety, and suicidal ideation [77] , with a quarter of them even perceiving an improvement of their mental health during the pandemic in one study [58] . On the other hand, the majority of studies found that individuals with MDD reported both a lower quality of life [70, 72, 77] and a decrease in mental health compared to the time before the pandemic [58] .

Individuals with SZ reported mostly no or only slight changes in their mental health [57, 58] , and did not find further therapeutic support to be necessary [58] .

This review is about the impact of COVID-19 on the mental health situation of individuals with BD, MDD, and SZ, gaining data from 19 different countries and areas.

In the first months of the crisis, individuals with mental disorders experienced, on average, more pronounced psychiatric symptoms. Nevertheless, some studies showing a reduction of psychiatric symptomatology were found as well. Individuals with affective disorders showed an impairment in mental health, while those with SZ seemed to be mostly unaffected by the pandemic on a mental level. Overall, older patients experienced fewer decline in mental health than younger patients. December 19, 2021

Volume 11 Issue 12

First and foremost, contradictory results about the impact of the pandemic on individuals with mental illness in general were found, showing both an increase and a decrease in psychiatric symptoms during the pandemic. The latter was reported more often, showing most commonly symptoms of depression, anxiety [56, 59, 60] , and stress [58] [59] [60] [61] [62] . Notwithstanding, these results suggest that individuals with SMI were less affected by the pandemic than HC [25] . This observation was made by numerous authors researching not only individuals with SMI but mental illness in general [27, 83] and might be applicable to this specific subgroup as well. The reason for this might be that individuals with mental disorders may be more used to periods of physical distancing and emotional upheaval due to disorder episodes, as Pan et al [25] similarly described. For HC, the pandemic has been a more drastic experience, severely influencing their daily lives and therefore leading to more pronounced symptoms of mental illness and a "normal"[25] reaction to this crisis. However, these results only feature the beginning of the COVID-19 pandemic, and the long-term effects on both HC and individuals with mental disorders require continued research.

While individuals with MDD were generally more worried about the pandemic and practiced more preventive behavior [62, 77] , those with BD seemed to suffer from more depressive symptoms without being as proactive about changing their situation [75] . Factors associated with higher levels of distress were largely connected to lifestyle [73] and socioeconomic environment [69] , emphasizing the influence of these factors as well as the importance of outside help and a stable social network [35] . Unemployment was a particularly important factor, as it was related to frustration, anxiety, and bad mood [69] , possibly leading to heightened fear about socioeconomic consequences[67]. Individuals with affective disorders are known to have a lower socioeconomic status and higher rates of unemployment than HC[84], making them more vulnerable for mental health degeneration in times of financial instability. In this context, the concept of resilience and strengthening it in individuals with psychiatric disorders, especially in individuals with BD, should be kept in mind for future interventions [85] .

Although those diagnosed with SZ were more worried and anxious than HC [76] , they seemed to be least affected by the crisis on a mental level among individuals with SMI, as the majority of SZ patients reported only little or no changes in their mental health [57, 58, 68] . This was explained by both a small sample size [58] and a disregard for "mundane worldly business" [68] . Possibly, they were indeed more preoccupied with their inner world, not focusing particularly on what happened during the pandemic. This coincides with the results about their apparent acceptance of a lack of information about COVID-19 [63] . In addition, individuals with SZ reported support from their social network [76] , helping them to lessen the mental burden in the wake of the pandemic.

Interestingly, more case reports were found about the exacerbation of SZ than of affective disorders, but these were not included in this review. This could be indicative either of a particular interest in such cases or an increased frequency of them. The latter may be explained by the diathesis-stress model [86] , according to which environmental triggers can influence psychiatric symptoms of SZ. Amongst other factors, stress and the subsequent increase in cortisol levels lead to an increased release of dopamine [86, 87] . Moreover, exacerbation might be associated with COVID-19 infection. Some patients who were infected were taking clozapine[87-89], which supports the hypothesis of this widely used drug increasing the risk for infection with COVID-19 [90, 91] . Likewise, stress, depression, and anxiety occurring in SZ patients with COVID-19 might advance an exacerbation [81, 82] . COVID-19 itself might cause delirium as well [92] . In conclusion, individuals with SZ may not have been profoundly affected, however, they are vulnerable, especially in case of an infection, which could lead to an exacerbation.

Young age seems to be a risk factor for developing more severe psychiatric symptoms during the pandemic. Younger individuals with SMI had worse mental health and more feelings of fear [63] and anxiety [69] than older individuals, who were mostly reported to remain stable [77, 79] . A connection of young age to financial concerns could be found [69] , which might be related to unemployment, an important factor for the development of mental health problems during the pandemic. Moreover, social relations played an important part in maintaining the mental health of older adults (age > 60 years) [77] . Many of them were perhaps retired, making the measures of physical distancing a less severe change to their lives. After all, unlike younger adults, they did not have to adjust to the abrupt change of working from home instead of daily meeting their co-workers and thereby connecting socially. Additionally, they did not have the burden of caring for their children staying at home as well. Furthermore, resilience, a protective factor, was found to be high in older adults with SMI [77, 79] . Resilience is known to rise with age[93], making it a possible reason for the better coping ability of older individuals with SMI, which indicates the need for increased resilience once again, especially in younger individuals with SMI.

An increased belief in pandemic-related news was found to be associated with both increased [55] and decreased [50] fear in individuals with SMI, which may be related to the nature of information. Regardless of whether these individuals were more or less [53] informed about COVID-19 and its prevention than HC, they were generally more fearful and worried about the pandemic [58, 76, 77] . This is concerning if it is related to less prevention behavior [50] , because individuals with SMI show more vulnerability to infection with COVID-19 than HC [94, 95] and should therefore practice strict measures of prevention. Notably, COVID-19 patients with SZ featured a higher in-hospital mortality rate than HC [96, 97] . Consequently, it is important for individuals with SMI to be supplied with information about the pandemic of adequate quality, which would lead to decreased fear and encourage them to protect both themselves and others.

Regarding the situation, increased treatment options for individuals with SMI are integral: Recommendations to use telepsychiatry have been made [98] [99] [100] and reports about its effectiveness have been given by several authors [101] . This kind of therapy seems to be well suited to face the situation of physical distancing, at least when it comes to patients without acute exacerbation of their condition requiring immediate medical intervention. In the light of elevated concerns about COVID-19-related healthcare shortages in individuals with mental illness [60, 64] , telepsychiatry gains in significance for easing the worries of these patients and helping them from afar. Inconsistent results were found across different studies researching whether the mental health situation of individuals with SMI increased or decreased, although the latter was reported more often. These conflicting outcomes could be explained by cultural, social, and economic background, the pandemic-related situation of different countries, as well as factors pertaining to the implementation of the studies, such as the use of non-standardized questionnaires. Nevertheless, this shows that generalizing the results might not be possible in some cases and should be taken into consideration, as many authors mentioned in their studies. Additionally, these discrepancies highlight the need for measuring individuals' socioeconomic situation and other variables influencing their mental health situation. This was done by several authors; however, it would be important to not only report these results, but also use the aforementioned variables as covariates to facilitate international comparison. Further limitations implicate more aspects to be taken into account for future research: The sample should be of adequate size, follow-up studies are needed to research causality and observe long-term effects, and standardized questionnaires about COVID-19related variables, such as those proposed by Chang et al [54] , should be used to enable better comparability. Additionally, the conduction of a meta-analysis would be ideal to better evaluate the impact of the pandemic on individuals with SMI.

The pandemic and its consequences have been leading to a decrease in the mental health situation of individuals with SMI across the world, especially those with affective disorders. Increasing symptoms of anxiety, depression, and stress were most frequent and higher in comparison to HC. Along with age and resilience, the main contributing factors seem to be of socioeconomic nature, with the shortage of treatment options, fear, adequate information, and social support being particularly important. This precarious situation necessitates a reinforcement of mental health services, first and foremost the usage of telepsychiatry. Moreover, it is paramount to supply patients with adequate information about COVID-19 and its prevention and to increase their resilience. Respecting scientific research about psychiatric disorders, both standardizations to enable generalization of results and the conduction of longterm follow-up studies are integral to further investigate SMI.

The coronavirus disease 2019 (COVID-19) is greatly influencing the mental state of individuals from all walks of life. Individuals with serious mental illness (SMI: bipolar disorder, major depressive disorder, and schizophrenia) are especially vulnerable to the reverberations of such a crisis, leading among other symptoms to an increase of depression and anxiety. The pandemic is an excellent opportunity to broaden the understanding of these disorders and improve methods of treatment.

Individuals with SMI having been researched in the course of several studies calls for a coherent analysis of all findings to gain an insight in the mind of these individuals, making their support more efficient. At the time of the search, no other review focusing on solely the clinical characteristics of individuals with SMI had been published in the searched databases.

This review aimed to assess the situation of individuals with SMI and their mental state during the COVID-19 crisis. The following questions were answered: (1) How are individuals with SMI affected by the pandemic in comparison to healthy controls (HC) and what are the main psychiatric symptoms they are displaying? (2) What are risk and protective factors that influence the severity of psychiatric symptoms and who is particularly vulnerable to these factors? And (3) How does symptomatology and frequency of illness episodes change during the course of the pandemic?

We systematically searched MEDLINE and PubMed (day of the final search: January 9, 2021), including terms related to the impact of the COVID-19 pandemic on the mental health of individuals with bipolar disorder, major depressive disorder, and schizophrenia. Only studies providing original data were included.

The search yielded 36 studies. The impact of the COVID-19 pandemic generally affected the mental health of individuals with SMI in a negative way, with individuals with affective disorders being more impacted than those with schizophrenia. The most common symptoms were those of depression, anxiety, and stress. Mental health was mainly influenced by age, resilience, and socioeconomic circumstances, particularly the shortage of mental health services, lack of social support, and inadequate information about COVID-19.

Mental health services, particularly telemental health services, should be reinforced to better support individuals with SMI and strengthen their resilience. Moreover, individuals with SMI should be supplied with information about the pandemic and the employment of protection measures. 

Archived: WHO Timeline -COVID-19

Severely increased generalized anxiety, but not COVID-19-related fear in individuals with mental illnesses: A population based cross-sectional study in Germany

Severe mental illness and risks from COVID-19

COVID-19 Concerns Among Old Age Psychiatric In-and Out-Patients and the Employees Caring for Them, a Preliminary Study

The Attitude towards Preventive Measures and Knowledge of COVID-19 Inpatients with Severe Mental Illness in Economically Underdeveloped Areas of China

COVID-19 and Severe Mental Illness: Impact on patients and its relation with their awareness about COVID-19

Knowledge of Prevention Measures and Information About Coronavirus in Romanian Male Patients with Severe Mental Illness and Severe Alcohol Use Disorder

Psychometric Testing of Three COVID-19-Related Scales Among People with Mental Illness

Factors related to preventive COVID-19 infection behaviors among people with mental illness

Effects of the COVID-19 pandemic and lockdown in Spain: comparison between community controls and patients with a psychiatric disorder. Preliminary results from the BRIS-MHC STUDY

A Longitudinal Investigation of the Effects of the COVID-19 Pandemic on the Mental Health of Individuals with Pre-existing Severe Mental Illnesses

Perceived Impact of Covid-19 Across Different Mental Disorders: A Study on Disorder-Specific Symptoms, Psychosocial Stress and Behavior

de Bartolomeis A; COVID-19 in Psychiatry Study Group. Psychological distress in patients with serious mental illness during the COVID-19 outbreak and one-month mass quarantine in Italy

Psychiatric symptoms related to the COVID-19 pandemic

Depression, dependence and prices of the COVID-19-Crisis

COVID-19 lockdown in people with severe mental disorders in Spain: Do they have a specific psychological reaction compared with other mental disorders and healthy controls?

A COVID-19 járvány miatt elrendelt első veszély-helyzet a pszichiátriai betegek szemszögéből : gondozói felmérés

COVID-19 Concerns Among Persons With Mental Illness

COVID-19-related self-harm and suicidality among individuals with mental disorders

Prevalence and correlates of fatigue and its association with quality of life among clinically stable older psychiatric patients during the COVID-19 outbreak: a cross-sectional study

Do pre-existing anxiety-related and mood disorders differentially impact COVID-19 stress responses and coping?

schizophrenic patients are unimpressed: A study on psychiatric inpatients

Mental health services for mood disorder outpatients in Milan during COVID-19 outbreak: The experience of the health care providers at San Raffaele hospital

Evidence for elevated psychiatric distress, poor sleep, and quality of life concerns during the COVID-19 pandemic among U.S. young adults with suspected and reported psychiatric diagnoses

Do psychiatric patients experience more psychiatric symptoms during COVID-19 pandemic and lockdown?

Serum 25-hydroxyvitamin D levels and psychological distress symptoms in patients with affective disorders during the COVID-19 pandemic

The Impact of the COVID-19 Pandemic on the Health and Coping Behaviors of Patients With Treatment-Resistant Depression

Mental health status of individuals with a mood-disorder during the COVID-19 pandemic in Australia: Initial results from the COLLATE project

Psychological and Emotional Impact of Patients Living in Psychiatric Treatment Communities during Covid-19 Lockdown in Italy

Experiences of American Older Adults with Pre-existing Depression During the Beginnings of the COVID-19 Pandemic: A Multicity, Mixed-Methods Study

Longitudinal Examination of COVID-19 Public Health Measures on Mental Health for Rural Patients With Serious Mental Illness

Psychiatric symptoms during the COVID-19 outbreak in older adults with bipolar disorder

Heightened Levels of Maladaptive Daydreaming Are Associated With COVID-19 Lockdown, Preexisting Psychiatric Diagnoses, and Intensified Psychological Dysfunctions: A Multi-country Study

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A sincere thank you to Ms. Nina Bonkat for her diligent proofreading of this paper.

Future research requires follow-up studies to determine causality and long-term effects, greater sample sizes, and standardization.