Direct and Indirect Mental Health Consequences of the COVID-19 Pandemic Parallel Prior Pandemics

A century ago, Karl Menninger, MD, documented adverse mental health consequences of the 1918 influenza pandemic,^1–3 publishing a case series of patients with postinfluenza mental illness. He concluded, “There is also no doubt but that influenza was the direct cause of thousands and thousands of [psychiatric] cases”^3(p244) and cited evidence of mental illness during pandemics as early as 1385.³ In his classic textbook, William Osler, MD, wrote in 1899, “Among the most important of the nervous sequelae [of influenza] are depression of spirits, melancholia and . . . dementia.”^4(p97) As Julius Althaus, MD, wrote in 1892, “[there were] A good many people who, without being actually laid up with definite symptoms of grip [influenza], yet seemed to some extent to be under the influence of the poison, as shown by such symptoms as general languor and depression”; sometimes “such endurable despondency as to make the patient feel that death was preferable to the state in which he found himself, and suicide the only means of relief,” and other times “other symptoms . . . causing the patients to make themselves drunk with alcohol or morphine, in order to find relief.”^5(p24,25)

Advances in psychiatry and data collection methodologies limit comparisons of mental health consequences of earlier pandemics and those observed during the COVID-19 pandemic, and pathogenic mechanisms of mental health conditions may vary. Nevertheless, these earlier descriptions have striking parallels with adverse mental health documented during recent epidemics.^6,7 For example, patients hospitalized for SARS (severe acute respiratory syndrome) or MERS (Middle East respiratory syndrome) commonly experienced acute confusion, depressed mood, anxiety, impaired memory, and insomnia.⁶

DIRECT MENTAL HEALTH EFFECTS

Emerging evidence highlights the importance of monitoring and addressing potential postacute neuropsychiatric sequelae of COVID-19. Analysis of 81 million electronic health records revealed that one third of COVID-19 survivors were diagnosed with neurologic or psychiatric conditions within six months.⁷ Patients with COVID-19 had an increased risk of such diagnoses compared with patients with other conditions (e.g., vs influenza, a 78% and 44% increased risk of first-time and any such diagnoses, respectively). Among patients with COVID-19, those admitted to intensive care had a 187% and 58% increased risk of first-time and any incident neurologic or psychiatric diagnosis. Heterogenous conditions observed (e.g., anxiety, ischemic stroke, intracranial hemorrhages, dementia, parkinsonism)⁷ may result from direct brain injury following viral infection, particularly given evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invasion of the central nervous system⁸ or from systemic factors, including inflammation, immune dysregulation, and adverse medical treatment responses.⁸ Even persons with mild COVID-19 and otherwise asymptomatic SARS-CoV-2 infection may experience psychiatric symptoms.⁷

INDIRECT MENTAL HEALTH EFFECTS

In addition to potential direct neuropsychiatric impacts of these viral infections, socioeconomic disruptions caused by pandemics and their mitigation can have indirect mental health consequences. Menninger asserted that the 1893 European financial panic was “indirectly [emphasis added] due to the depressing effect of . . . influenza, and the mutual loss of confidence and enthusiasm which it is well known to produce.”^3(p243,244) Measuring indirect mental health effects of infectious disease outbreaks is particularly difficult, especially given differing sociopolitical contexts (e.g., World War I during the 1918 pandemic). However, evidence from the COVID-19 pandemic reveals considerably elevated levels of adverse mental health symptoms compared with prepandemic years, even in the absence of widespread SARS-CoV-2 transmission. As early as April 2020, anxiety and depression symptoms in the United States were two to four times as prevalent as in 2019—and similarly high in Australia despite exceptionally low COVID-19 prevalence.⁹

During the COVID-19 pandemic, governments have implemented stringent mitigation policies, including stay-at-home orders, gathering bans, economic shutdowns, school closures, and travel bans to reduce SARS-CoV-2 transmission. As unemployment, loneliness, and social isolation increased and financial security and social interaction decreased, factions of resistance emerged, perhaps because of adjustment disorders with disturbance of conduct, including norm-violating or inappropriate conduct (e.g., mask refusal), aggressive behavior (e.g., violent protests, purposefully exposing others to SARS-CoV-2), and other maladaptive reactions (e.g., substance use). US Army major George Soper, who discovered asymptomatic transmission of typhoid in the United States, commented on these social dynamics during the 1918 pandemic: “It does not lie in human nature for a man who thinks he has only a slight cold to shut himself up in rigid isolation as a means of protecting others.”^10(p502) That attitude is apparent today, as moral appeals for mutual protection from COVID-19 have often fallen on deaf ears amid socioeconomic disruption of uncertain duration.

People who embrace public health guidance may experience social isolation, concerns of COVID-19 morbidity and mortality, and grief and guilt associated with the isolated deaths of loved ones. Some may feel resentment toward what Paul Farmer, MD, PhD, designates containment nihilism, referring to approaches that abandon public health measures to contain SARS-CoV-2 and instead endorse enormous mortality to achieve population-level immunity. By June 2020, 40.9% of 5412 surveyed US adults reported adverse mental health symptoms or substance use, and suicidal ideation was twice as prevalent as in 2018.¹¹ Young adults, unpaid caregivers, Black persons, Latinx persons, essential workers, people with disabilities, and individuals with psychiatric or substance use conditions have disproportionately experienced adverse mental health symptoms. Anxiety and depression symptom levels among US adults continued to climb through February 2021,¹² likely representing direct and indirect effects of the COVID-19 pandemic complemented by seasonality. Provisional data indicate that US deaths classified as suicides declined by 2677 in 2020 versus 2019.¹³ However, unintentional injury deaths increased by 19 136 during the same interval, driven by a record increase in drug overdose deaths.¹³ Taken together, deaths of despair increased substantially in 2020.

RESPONDING TO MENTAL HEALTH NEEDS

Longstanding inadequate funding of mental and behavioral health services has left countries underprepared to respond to mental health needs during the COVID-19 pandemic. Despite an estimated $1 trillion economic cost of anxiety and depression alone—and a four-to-one benefit–cost ratio for investment in relevant treatment—mental health expenditure accounted for less than 2% of 2017 government health budgets.¹⁴ Addressing the chronic underinvestment in mental health infrastructure can reduce the impact of such unique challenges, with added benefits for population-level health and productivity. Fortunately, early indicators of mental health effects of the pandemic^9,11 led the US president to sign Executive Order 13954, allocating $425 million to address mental health, the opioid crisis, and suicide. Moreover, the US Congress has allocated $1.15 billion to study postacute sequelae of COVID-19, including neuropsychiatric sequelae.

A comprehensive pandemic response will require recognition of both direct and indirect mental health consequences of the COVID-19 pandemic. Failure to recognize that COVID-19 is among the infectious diseases that may directly cause psychiatric conditions has led some policymakers to incorrectly conclude that adverse mental health consequences of the pandemic are driven solely by mitigation, creating a false choice between COVID-19 containment and preserving mental health. Similarly, failure to appreciate that fear, bereavement, and pandemic-associated life disruption can have adverse mental health consequences could lead policymakers to allocate mental health resources only to those who have had SARS-CoV-2 infection. Moreover, social determinants of health and the impacts of systemic and institutional racism and economic downturns compound pandemic-related stressors. Parallel stressors are, however, not unique to the COVID-19 pandemic; the 1918 influenza pandemic occurred during World War I alongside sociopolitical turmoil.

In describing the commonality of depression following influenza observed by internists and general practitioners in the wake of the 1918 influenza pandemic, Menninger states, “‘Since I had influenza’ is the touchstone of many a clinical history of depression.”^2(p257) Public health, societal, and medical efforts can help to reduce this experience with COVID-19. Public health prevention efforts should include promotion of COVID-19 prevention measures and coordination of COVID-19 vaccine distribution. Societal efforts should include integrated and sustained community-wide education campaigns and interventions to reduce social and health inequalities, both backed by strong legislative platforms. Medical efforts should prioritize expansion of mental health care access, as the already considerable percentage of US adults with unmet mental health care needs increased by 27% during the pandemic¹³ and many countries rely on out-of-pocket payment for mental health services.¹⁵ Increased, equitable access to tele–mental health services, digital mental health programs, and safe in-person services may mitigate the long-term consequences of neglecting this overlooked aspect of the pandemic.

Moreover, given evidence of neuropsychiatric consequences of SARS-CoV-2 infection,^7,8 enhanced mental health monitoring of all individuals who contract SARS-CoV-2 may be warranted, with recognition that psychiatric symptoms experienced by patients with COVID-19 may reflect experiential aspects of COVID-19 (e.g., self-stigma) or indirect mental health effects of the pandemic, which are not mutually exclusive from potential direct brain effects of COVID-19. Given the potential for mental health challenges affecting patients more broadly, integration of mental and behavioral health services into medical practices could help to better support community mental health needs.

With the global prevalence of laboratory-confirmed SARS-CoV-2 infections approaching 200 million in July 2021 and the true number of infections considerably larger, greatly enhanced research and clinical initiatives are needed to characterize and address the direct and indirect mental health consequences of the COVID-19 pandemic and to mitigate the detrimental impacts of mental health stigmatization. As Menninger warned in 1919,² failure to do so could further overwhelm underprepared US and global mental health care systems, the shortcomings of which were exposed beginning early during the current pandemic.¹⁵