Elevated risk of COVID-19 in people with dementia

Individuals with dementia have an increased risk of contracting and experiencing a poor outcome from COVID-19, according to new research published in Alzheimer’s & Dementia. The findings underline the need to develop strategies to protect patients with dementia from SARS-CoV-2 infection while avoiding the potentially detrimental effects of social isolation.

“Previous studies by others showed that the altered blood–brain barrier in people with Alzheimer disease (AD) predisposes them to viral and bacterial infections,” explains corresponding author Rong Xu. “In addition, the memory impairment associated with dementia might interfere with the patient’s ability to adhere to preventive measures for COVID-19, such as social distancing, mask wearing and hand sanitizing.”

Xu and colleagues analysed de-identified, population-level electronic health record data from 61,916,260 individuals in the USA aged ≥ 18 years, 1,064,960 of whom were recorded as having dementia. The researchers used these data to examine the impact of dementia on the risk of developing COVID-19, and also on the probability of hospitalization and death as a result of the condition.

The analysis showed that people with dementia had a twofold increased risk of contracting COVID-19. The odds were highest in people with vascular dementia (adjusted OR (AOR) 3.17), followed by presenile dementia (AOR 2.62) and AD (AOR 1.86). In addition, dementia was associated with a greater likelihood of hospitalization and death as a consequence of COVID-19. The strong link between COVID-19 and vascular dementia indicates a possible role for pre-existing cerebrovascular pathology in SARS-CoV-2 infection.

The researchers also found that, among people with dementia, Black individuals had a higher risk of COVID-19 than white individuals, and were more likely to be hospitalized or die from the condition. These findings are consistent with COVID-19-related racial disparities that have been observed in the wider population.

Xu and colleagues noted that people with dementia often have comorbidities that are risk factors for COVID-19, such as hypertension, cardiovascular disease, obesity or type 2 diabetes. Moreover, many patients with dementia reside in nursing homes, which tend to be hotspots for SARS-CoV-2 infection. However, the correlations between COVID-19 and dementia remained statistically significant after the researchers had controlled for these potential confounding factors.

The analysis showed that people with dementia had a twofold increased risk of contracting COVID-19

“Prior evidence indicates a bidirectional relationship between viral infections and dementia, whereby people with dementia have an increased risk of viral infection, and a poor immune response to infection places individuals at an increased risk of dementia,” comments Xu. “Further research is warranted to understand the underlying mechanisms — both biological and socioeconomic — of the increased risk of COVID-19 in patients with dementia, and to determine whether SARS-CoV-2 infection accelerates cognitive decline or triggers dementia.”