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Battling the Modern Behavioral Epidemic of Loneliness: Suggestions for Research and Interventions.

Since ancient times, millions of people have died of epidemics of plague, flu, cholera, and other infections caused by bacteria, viruses, or other microorganisms. Major advances in medicine have largely eliminated these mass killers with vaccines and antibiotics. However, modern societies are facing a new kind of epidemics: behavioral epidemics. The annual rates of mortality by suicides and opioid overdose have been escalating over the last 2 decades and today are responsible for the death of 1 American every 5.5 minutes. Consequently, the average US life span, which had been rising progressively since mid-1950s, has fallen for the first time.1 Contributing to these epidemics of suicides and opioid use is not a pathogenic microbe, but rather a hard to detect and lethal behavioral toxin of loneliness. Loneliness may be defined as subjective distress resulting from a discrepancy between desired and perceived social relationships.2 Loneliness (or perceived social isolation) is associated with but distinct from objective social isolation, which is defined by the number of persons in the environment. Loneliness is a subjective state and a personality trait determined by genetics and hormonal and cerebral pathophysiology. Perceived and objective social isolation increase the risk of mortality comparable with smoking and obesity.3 An annual mortality of 162 000 Americans is attributable to social isolation, exceeding the number of deaths from cancer or stroke.4 In the United Kingdom, the economic association of loneliness with businesses was estimated at more than $3 billion annually, leading to the establishment of a Ministry of Loneliness. According to the British historian Alberti, the term loneliness did not exist in the English language until 1800 (https://www.theguardian.com/commentisfree/2018/ nov/01/loneliness-illness-body-mind-epidemic). The word that described a similar state was oneliness, which meant being alone without distress. According to Alberti, beginning at the turn of the 19th century, industrialization reduced social connectedness and spawned loneliness. This problem has grown exponentially over the past couple of decades, with a doubling of the prevalence of loneliness. Our recent study5 found that 76% of adult Californians experienced moderate to severe loneliness that was associated with worse physical, cognitive, and mental health. Loneliness peaked in the late 1920s, mid1950s, and late 1980s.5 Another study of older adults in rural Anhui, China, reported estimates of 57% for moderate loneliness and 21% for moderate to severe loneliness.2,6 Why has this unprecedented worldwide rise in loneliness, suicides, and opioid use developed during recent years? While multiple factors are responsible for each of these behavioral epidemics and a demonstration of direct causality is difficult, there is probably a common underlying thread of social anomie and disconnection resulting from the rapid growth of technology, social media, globalization, and polarization of societies. Although technology and globalization have improved the quality of life in many ways, they have also upended social mores and disrupted traditional social connections. Information overload, 24-hour connectivity, countless but superficial and sometimes harmful social media relationships, and heightened competition have elevated the level of stress in the modern society. A recent Gallup poll reported a 25% increase in selfreported stress and worry in the United States over the past 12 years (https://www.gallup.com/analytics/ 248909/gallup-2019-global-emotions-report-pdf. aspx). While loneliness is prevalent in the general population, it is more common and more severe in persons with serious mental illnesses.7 Below we discuss suggestions for research and interventions associated with loneliness at individual and societal levels, including psychiatric patients.