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Disclosures: The researchers report no relevant financial disclosures.
February 09, 2021
4 min read
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Dementia represents independent risk factor for COVID-19 infection

Disclosures: The researchers report no relevant financial disclosures.
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Patients with dementia, particularly patients with vascular dementia, experienced an increased risk for COVID-19, according to findings published in Alzheimer’s Disease & Dementia.

The researchers also found that Black patients with dementia had a greater risk for COVID-19 than white patients.

Dementia
Patients with dementia experienced an increased risk for COVID-19 compared with patients without dementia. Source: Adobe Stock

“Strong risk factors for cognitive decline and dementia include cardiovascular diseases, diabetes, obesity and hypertension. Many of these common comorbidities in patients with dementia are also demonstrated risk factors for COVID-19 and are associated with worse clinical outcomes,” Quangqiu Wang, an artificial intelligence specialist in the Center for Artificial Intelligence in Drug Discovery at Case Western Reserve University School of Medicine, and colleagues wrote. “In addition, the memory impairment associated with dementia may interfere with the patient’s ability to comply with preventive measures for COVID-19 such as social distancing, mask wearing and frequent hand sanitizing.”

Further, prior findings from other researchers showed that the altered blood-brain barrier in patients with Alzheimer’s disease “predisposes them to viral and bacterial infections,” Pamela B. Davis, MD, PhD, dean of Case Western Reserve University School of Medicine, Arline H. and Curtis F. Garvin Research Professor and professor in the department of pediatrics at Case Western Reserve University School of Medicine, and Rong Xu, PhD, professor of biomedical informatics and director of the Center for Artificial Intelligence in Drug Discovery at Case Western Reserve University School of Medicine, told Healio Neurology. As a result, they hypothesized that “the altered blood-brain barrier in these individuals may also lead to an increased risk for SARS-CoV-2 viral infection,” according to Davis and Xu.

The researchers performed a retrospective case-control examination of patient electronic health records from 61.9 million adult and senior patients aged 18 years and older in the United States through August 21, 2020. They pulled the EHR data form 360 hospitals and 317,000 providers across 50 states, which represented 20% of the U.S. population, according to the study results.

Wang and colleagues analyzed the link between dementia and risk for COVID-19, adjusting for age, sex, race, comorbidities, transplantation history and nursing home stays. The researchers performed a separate analysis for each of the five dementia types and examined the differential impact of demographic factors on COVID-19 risk. Outcome measures included COVID-19 diagnosis, hospitalization and death.

The overall study population of 61.9 million included more than 1 million patients with dementia. Specific types of dementia included AD (0.57%), post-traumatic dementia (0.2%), presenile dementia (0.05%), senile dementia (0.28%) and vascular dementia (0.19%).

The group of 15,770 adult and senior patients diagnosed with COVID-19 included 810 patients with dementia (5.14% of the COVID-19 population), including 260 patients with AD (1.65% of the COVID-19 population), 70 with post-traumatic dementia (0.44%), 40 with presenile dementia (0.25%), 140 with senile dementia (0.89%) and 170 with vascular dementia (1.08%).

Patients with dementia experienced an increased risk for COVID-19 compared with patients without dementia (adjusted OR [aOR] = 2; 95% CI, 1.94-2.06), with the strongest effect demonstrated for vascular dementia (aOR = 3.17; 95% CI, 2.97-3.37), followed by presenile dementia (aOR = 2.62; 95% CI, 2.28-3), AD (aOR = 1.86; 95% CI, 1.77-1.96), senile dementia (aOR = 1.99; 95% CI, 1.86-2.13) and post-traumatic dementia (aOR = 1.67; 95% CI, 1.51-1.86).

Xu Rong

"Our paper shows a highly significant twofold increase in COVID-19 infections in patients with dementia, even after adjusting for known COVID-19 risk factors,” Davis and Xu said. “There is a less than one in 1,000 chance that this result occurred by chance alone.”

Black patients with dementia experienced an increased likelihood of COVID-19 infection compared with white patients with dementia, even after adjusting for age, sex and COVID-19 risk factors (aOR = 2.86; 95% CI, 2.67-3.06). The researchers observed similar racial disparities for AD and for vascular dementia.

Overall risk for hospitalization among all patients diagnosed with COVID-19 was 25.17%, according to study findings. More than half of the patients with dementia who were diagnosed with COVID-19 (59.26%) were hospitalized, with higher rates for Black patients (73.08%) compared with white patients (53.85%; P < .01). By comparison, 14,960 adult and senior patients with COVID-19 but not dementia were hospitalized in the 6-month period studied (23.26%), with higher rates for Black patients (31.99%) compared with white patients (18.57%; P < .001).

Adult and senior patients diagnosed with COVID-19 experienced a 6-month mortality risk of 5.64%, according to the findings from Wang and colleagues. Among the patients with dementia and COVID-19, 170 died (20.99%), with similar rates between Black patients (23.08%) and white patients (19.23%).

“As has been found in many studies of vulnerability to COVID-19 infection, our study found that Black patients have two to three times the risk for COVID-19 compared to white patients,” Davis and Xu said. “Once infected, they have similar risk for hospitalization and death.”

In addition to specific racial disparities, the findings from the present study also highlighted the susceptibility of patients with dementia to COVID-19.

“Known comorbidities for COVID-19 are certainly part of the vulnerability of dementia patients to COVID-19, but even after adjusting for these factors (such as nursing home residence, age, high blood pressure, diabetes and others), dementia was an independent risk factor for infection,” Davis and Xu said. “This vulnerability, together with the observation of others that patients with dementia benefit greatly from human contact, would argue for prioritizing vaccination for patients with dementia and their caregivers.”