Abstract
BACKGROUND: It has been indicated that the health impact of COVID-19 is potentially greater in individuals from lower socioeconomic status than in the overall population. AIMS: To examine how the spread of COVID-19 has altered the general public's mental health, and whether such changes differ in relation to individual income. METHOD: An online longitudinal survey was conducted at three different time periods during the pandemic. We recruited 1993 people aged 20-70 years, living in the Tokyo metropolitan area in Japan. Participants' mental health was measured with the six-item version of the Kessler Psychological Distress Scale; the existence of severe psychological distress was ascertained through the cut-off data. Multiple logistic and mixed-model ordinal logistic regression analyses were performed, with income as the independent variable. RESULTS: Of the participants, 985 were male, with a mean age of 50.5 (±15.8) years. Severe psychological distress percentages for each tested period were 9.3%, 11.2% and 10.7% for phases 1, 2 and 3, respectively. Between phases 1 and 2 or phases 2 and 3, the group that earned <£15 000 had significantly higher propensity to develop severe psychological distress than the group that earned ≥£45 000 (odds ratio 2.09, 95% CI 0.95-4.56 between phases 1 and 2; odds ratio 3.00, 95% CI 1.01-9.58 between phases 2 and 3). CONCLUSIONS: Although there has been significant deterioration in mental health among citizens during the COVID-19 pandemic, this was more significant among those with lower income. Therefore, mental health measures that focus on low socioeconomic groups may be necessary.