Intensified preventive measures during the COVID-19 pandemic, such as lockdown and social distancing, heavily increased the perception of social isolation (i.e., a discrepancy between one's social needs and the provisions of the social environment) among young adults. Social isolation is closely associated with situational loneliness (i.e., loneliness emerging from environmental change), a risk factor for depressive symptoms. Prior research suggested vulnerable young adults are likely to seek support from an online social platform such as Reddit, a perceived comfortable environment for lonely individuals to seek mental health help through anonymous communication with a broad social network. Therefore, this study aims to identify and analyze depression-related dialogues on loneliness subreddits during the COVID-19 outbreak, with the implications on depression-related infoveillance during the pandemic. Our study utilized logistic regression and topic modeling to classify and examine depression-related discussions on loneliness subreddits before and during the pandemic. Our results showed significant increases in the volume of depression-related discussions (i.e., topics related to mental health, social interaction, family, and emotion) where challenges were reported during the pandemic. We also found a switch in dominant topics emerging from depression-related discussions on loneliness subreddits, from dating (prepandemic) to online interaction and community (pandemic), suggesting the increased expressions or need of online social support during the pandemic. The current findings suggest the potential of social media to serve as a window for monitoring public mental health. Our future study will clinically validate the current approach, which has implications for designing a surveillance system during the crisis.

翻译：在COVID-19疫情期间，封锁和社交距离等强化预防措施严重加剧了年轻人对社会隔离的感知（即一个人的社交需求与社会环境供给之间的差距）。社会隔离与情境性孤独（即因环境变化而产生的孤独感）密切相关，而情境性孤独是抑郁症状的风险因素。先前研究表明，脆弱的年轻人可能倾向于从Reddit等在线社交平台寻求支持。对孤独个体而言，Reddit被视为通过匿名沟通与广泛社交网络联系以寻求心理健康帮助的舒适环境。因此，本研究旨在识别和分析COVID-19疫情期间孤独主题子论坛中与抑郁相关的对话，并探讨其对疫情期间抑郁相关信息监控的意义。本研究采用逻辑回归和主题建模对疫情前后孤独子论坛中抑郁相关讨论进行分类和检验。结果显示，疫情前后抑郁相关讨论（即涉及心理健康、社交互动、家庭和情感等主题）的数量显著增加，且这些主题在疫情期间被报告为挑战。我们还发现，孤独子论坛中抑郁相关讨论的主导主题发生了转变，从约会（疫情前）转向在线互动和社区（疫情期间），表明疫情期间对在线社交支持的表达或需求有所增加。当前研究结果揭示了社交媒体作为监测公众心理健康窗口的潜力。未来研究将对该方法进行临床验证，这为疫情期间设计监控系统提供了启示。