by Dr. Juliette Dufour
For May 2022, we have selected: Y. Wang et al, Clinical outcomes of COVID-19 infection among patients with Alzheimer’s disease or mild cognitive impairment, Alzheimer’s & Dementia, 2022. DOI: 10.1002/alz.12665.
COVID-19 causes a wide spectrum of symptoms with central nervous system (CNS) complications involving confusion and delirium. The fact that COVID-19 and Alzheimer’s disease (AD) share several risk factors such as age, hypertension, diabetes, cardiovascular disease, and the presence of the apolipoprotein E (APOE) ε4 allele, predisposes patients with AD to infection by the SARS-CoV-2 virus. Currently there is no report on occurrence of COVID-19 among patients with MCI.
Our authors of the month conducted this retrospective case-control study in order to investigate the association of AD with the risk of COVID-19 infection (adjusted for comorbidities and sociodemographic factors). They used both classical and propensity score weighted logistic models to compare COVID-19 outcomes between patients with AD or mild cognitive impairment (MCI) to those without cognitive impairment and examined effect of angiotensin converting enzyme (ACEI)/ angiotensin II receptor blockers (ARB) prescription.
In total, 436,823 patients (aged 50-90 years-old) were tested for COVID-19 and included. Among them, they identified:
- 40,993 subjects (9.4%) with positive COVID-19 test
- 5,128 AD patients (1.2%) and 431,695 non-AD subjects
- Among these non-AD subjects: 26,330 (7.7%) MCI and 405,365 non-MCI
- 2,446 treated patients: 1,761 ACEI only, 685 ARB only (exclusion ACEI + ARB)
The authors revealed several significant results:
- There was a statistically significant association between AD and increased odds of infection and mortality
- AD patients were associated with higher odds than non-AD subjects of being diagnosed with COVID-19
- Patients with AD had a significantly increased risk of death
- Increased odds of hospitalisation associated with AD patients was observed
- MCI was not found to be a risk factor for infection. But subjects with MCI exhibited poor clinical outcomes:
- No significant association of MCI with COVID-19 infection
- Patients with MCI were associated with: (i) higher ORs of hospitalisation, (ii) use of ICU or mechanical ventilators and (iii) mortality
- Prescribing ARBs but not ACEIs was significantly associated with a lower risk of COVID-19 occurrence among AD and MCI patients. Neither ACEIs nor ARBs had a significant association with any of the severity levels of COVID-19.
This study is one of the largest retrospective case-control studies evaluating the association of AD/MCI and COVID-19 infection together with information on medication treatment and clinical outcomes. This study reveals increased odds of COVID-19 infection and mortality among AD patients and beneficial effect of ARB prescription.
However, future studies are needed to understand the pathological changes that may explain increased occurrence of COVID-19 among AD and MCI patients.