Impact of Severe COVID-19 on Accelerating Dementia Onset: Clinical and Epidemiological Insights

ImportanceSevere COVID-19 infection has been associated with neurological complications, but its role in accelerating cognitive decline remains unclear. ObjectiveTo determine whether individuals hospitalized for severe COVID-19 exhibit a higher incidence of new onset cognitive impairment compared to those hospitalized for other conditions. DesignA retrospective study emulating a target trial using Mass General Brigham electronic health records (March 2020-August 2024). The causal effect of COVID-19 hospitalization was estimated via cumulative incidence functions accounting for the competing risk of death. SettingMulticenter hospital-based study across the Mass General Brigham healthcare system. ParticipantsA total of 221613 hospitalized patients met the eligibility criteria, including 6454 (2.0%) admitted due to COVID-19 and 215159 (98.0%) for all other conditions. Patients were excluded if they had less than three months of follow-up (due to censoring, cognitive impairment, or death), were younger than 55 years at baseline, or had no prior visit to Mass General Brigham in the year before baseline. Main Outcomes and MeasuresThe primary outcome was new-onset cognitive impairment, identified via ICD codes and dementia medication prescriptions. The primary analysis estimated the hazard ratio for cognitive impairment with COVID-19 hospitalization relative to other hospitalizations, along with the risk difference at 4.5 years estimated via cumulative incidence functions. Inverse propensity score weighting was used to balance covariates (age, sex, comorbidities, hospitalization period). ResultsAmong eligible patients (mean [SD] age, 69.55 [9.42] years, 55% female), those hospitalized for COVID-19 were significantly older and had more comorbidities (p < 0.05). COVID-19 hospitalization was associated with a higher risk of developing cognitive impairment (Hazard Ratio: 1.14 [95% CI: 1.02-1.30], P = 0.018). At 4.5 years, the cumulative incidence of cognitive impairment was 12.5% [95% CI: 11.3-13.5] in the COVID-19 group, compared to 11.6% [95% CI: 11.1-12.1] in the non-COVID-19 group. Conclusions and RelevanceSevere COVID-19 infection was associated with an elevated risk of developing clinically recognized cognitive impairment. Future studies are needed to validate findings in other health care settings. Early screening and intervention for cognitive decline may help optimize long-term outcomes for COVID-19 patients. Key pointsO_ST_ABSQuestionC_ST_ABSDo individuals hospitalized for severe COVID-19 have a higher incidence of new-onset cognitive impairment compared to those hospitalized for other conditions? FindingsIn this retrospective study of 221613 hospitalized patients, including 6454 hospitalized due to COVID-19, a higher incidence of new-onset cognitive impairment was observed among COVID-19 patients. MeaningEarly recognition and diagnosis of dementia in individuals with severe COVID-19 are crucial for optimizing long-term patient outcomes.