The evidence on the predictors of mental health in the COVID-19 pandemic has revealed contradictory findings, which prevent effective screening for mental health assistance. This study aims to identify the predictors of mental health issues, specifically examining age as a nonlinear predictor. Based on a survey of 474 adults using snowball sampling under the COVID-19 pandemic during April 1th–10th, 2020, in Iran, we found that age had a curvilinear relationship with nonsomatic pain, depression, and anxiety. Specifically, it predicted pain, depression, and anxiety disorders, negatively among adults younger than 45 years, yet positively among seniors older than 70 years. Adults who were female, were unsure about their chronic diseases, or exercised less were more likely to have mental health issues. This study, being the first paper to examine age curvilinearly, suggests future research to pay more attention to nonlinear predictors of mental health disorders in the COVID-19 pandemic.

关于 COVID-19 大流行中心理健康预测因素的证据揭示了相互矛盾的发现，这阻碍了心理健康援助的有效筛查。本研究旨在确定心理健康问题的预测因素，特别是将年龄作为非线性预测因素。根据 2020 年 4 月 1 日至 10 日期间在伊朗 COVID-19 大流行期间对 474 名成年人进行的滚雪球抽样调查，我们发现年龄与非躯体疼痛、抑郁和焦虑呈曲线关系。具体来说，它对疼痛、抑郁和焦虑症的预测对 45 岁以下的成年人呈负向预测，而对 70 岁以上的老年人则呈正向预测。女性、对自己的慢性疾病不确定或锻炼较少的成年人更有可能出现心理健康问题。这项研究是第一篇以曲线方式研究年龄的论文，建议未来的研究应更多​​关注 COVID-19 大流行中心理健康障碍的非线性预测因素。