Accelerated cognitive decline after the COVID‐19 pandemic in a community population of older persons with cognitive impairment: A 4‐year time series analysis in the Tokyo Metropolis area

Aim The coronavirus disease 2019 (COVID‐19) pandemic has led to lifestyle restrictions and might be associated with long‐term changes in cognitive function. The aim of the present study was to elucidate the overall effect of the COVID‐19 pandemic on the cognitive trajectory of a cohort of patients with cognitive impairment. Methods We enrolled 160 patients who had been making regular visits to a medical center for dementia. Cognitive function was assessed based on changes in scores on the Mini‐Mental State Examination before and during the COVID‐19 pandemic throughout a 4‐year period. The trajectory of cognitive decline was determined by carrying out a time series analysis using a state‐space model. Results Crude analysis showed that the Mini‐Mental State Examination scores decreased from 20.9 ± 4.4 points (mean ± SD) at the time of the initial cognitive assessments to 17.5 ± 5.6 points at the time of the final assessments, and the decline rate was 1.15 ± 1.78 points per year (P