Association Between Dementia Development and COVID-19 among Individuals Who Tested Negative for COVID-19 in South Korea: A Nationwide Cohort Study.

We aim to assess whether the number of newly diagnosed dementia increases and whether comorbid psychiatric symptoms of patients with dementia worsen, in people who were tested for COVID-19. We used electronic medical records from a nationwide cohort consisting of people who tested positive (positive group), tested negative (negative group), and those who did not receive the test (control group) for COVID-19. For people with neither a history of dementia nor mild cognitive disorder (MCI), the negative group was more likely to develop dementia than the control group, and less likely to develop MCI than the positive group. For people who already had dementia, the negative group was more likely to develop comorbid psychiatric disorders than the control group, but less likely than the positive group. These findings suggest the necessity of managing mental health not only for patients with COVID-19 but also for people who tested negative for COVID-19.