Dementia patients at increased risk for COVID-19, severe cases

Dementia patients with COVID-19 were found to have significantly worse outcomes in both mortality risk and hospitalization risk compared to other patients.

SHAARE ZEDEK hospital team members in the coronavirus ward. (photo credit: NATI SHOHAT/FLASH90)
SHAARE ZEDEK hospital team members in the coronavirus ward.
(photo credit: NATI SHOHAT/FLASH90)
Dementia patients are at an increased risk for COVID-19 and an increased risk for severe cases of the disease caused by the novel coronavirus, according to a new study published by the Alzheimer's & Dementia journal of the Alzheimer's Association on Tuesday.
The study found that patients with dementia had a significantly increased risk of contracting COVID-19, compared to patients without dementia.
The majority of dementia patients have additional chronic health conditions, including cardiovascular diseases, diabetes, obesity and hypertension, which are also risk factors for COVID-19. The memory impairment associated with dementia may also interfere with dementia patients' abilities to follow preventative measures, such as social distancing, mask wearing and proper hygiene.
Dementia patients also have a damaged blood-brain barrier, which allows certain bacteria and viruses to access the brain more easily, and, as the coronavirus has been shown to affect the brain, the researchers hypothesized that dementia patients were at a greater risk for adverse outcomes.
Even after adjusting for the COVID-19 risk factors that many dementia patients have, the researchers found that dementia patients still had a higher risk for contracting COVID-19 compared to patients without dementia. The researchers explained that this may be due to a number of reasons, including socioeconomic determinants, behavioral factors and lifestyle. For example, dementia patients' impaired memory can limit their ability to comply with preventative measures. The damaged blood-brain barrier may also increase dementia patients' susceptibility to the coronavirus infections. Due to limited information available on all these factors, the researchers were unable to determine which and how these factors contributed to increased COVID risk among dementia patients.
The researchers found substantial differences between the different types of dementia in respect to COVID-19 risk, with vascular dementia patients showing the greatest risk. There was not enough information available to examine some rarer types of dementia, including Lewy body dementia and mixed dementia. Vascular dementia is attributable to cerebrovascular pathologies and alteration in cerebral blood vessels and damage to the blood-brain barrier. Researchers speculated that since the virus can attack the brain or its blood vessels directly, the issues with the brain are a risk for coronavirus infections. Even after adjusting for other risk factors, the study found that vascular dementia patients were over three times more likely than other patients to be infected with the novel coronavirus.
Among dementia patients, Black patients were twice as likely to be infected by the novel coronavirus than White patients. The risk factor was similar both before and after adjusting for other COVID-19 risk factors, so researchers believe that non-medical factors, including access to healthcare, socioeconomic status and social adversity could contribute to the increased risk factor among Black patients, although not enough socioeconomic information was available to assess how these factors differentially affected COVID-19 risk.
Despite evidence that the elderly population is more at risk for infection than the rest of the population, the study found that advanced age had no additional effect on the risk of getting COVID-19 among dementia patients after adjusting for additional risk factors. The researchers speculated that older people, including older dementia patients, may be more likely to stay at home, lowering their exposure to the virus. The study also did not find any disparity between the sexes in COVID-19 risk among dementia patients, despite prior studies showed substantial sex disparities in COVID-19 mortality and dementia risk.
Dementia patients with COVID-19 were found to have significantly worse outcomes in both mortality risk and hospitalization risk compared to patients with COVID-19 but not dementia or dementia patients without COVID-19. While black dementia and COVID-19 patients were more likely to require hospitalization than white dementia and COVID-19 patients, their mortality risk was not found to be higher.
The study was conducted by researchers QuanQiu Wang, Rong Xu, Pamela B. Davis and Mark E. Gurney with anonymous electronic health record data from 360 hospitals and 317,000 health providers across 50 states, representing about 20% of the US population.
The data used by the study covered 61,916,260 adults and seniors, including 1,064,960 dementia patients. Some 15,770 of the people represented in the data had COVID-19 and 810 patients (5.14% of the COVID patients) had both dementia and COVID-19. The researchers adjusted for demographics and COVID-19 risk factors.
The researchers added that it is still unclear if the novel coronavirus accelerates cognitive decline in dementia patients or leads to long-term cognitive impairments or triggers dementia.
COVID-19 has been found to cause neurological symptoms and there is increasing evidence that the virus can infect neurons and affect brain function through chronic hypoxia, metabolic dysfunction, systemic inflammation, and immune dysregulation. The researchers stated that they anticipate significant long-term neurological effects of coronavirus infections in triggering or worsening dementia in COVID-19 survivors and expect a higher prevalence of dementia in COVID-19 patients compared to the non-infected population in the future.