SARS-CoV-2 infection has a significant impact on cognitive function in patients with pre-existing dementia, according to new research published in the Journal of Alzheimer’s Disease Reports. Patients with all dementia subtypes included in the study experienced rapidly progressive dementia after SARS-CoV-2 infection.
Since the first wave of COVID-19, neurologists have warned of the appearance of both acute and long-term neurological syndromes and neuropsychiatric sequelae after suffering from this infectious disease. Until now, information about the impact of COVID-19 on human cognition remains unclear, with most cases pointing to the presence of brain fog.
In order to better understand and dispel what is behind this COVID-related fog, a group of researchers analyzed the effects of COVID-19 on the cognitive decline of 14 patients with pre-existing dementia (four with Alzheimer’s disease, five with dementia vascular disease, three with dementia due to Parkinson’s disease and two with the behavioral variant of frontotemporal dementia), who had suffered further cognitive decline after experiencing COVID-19.
Principal investigators Souvik Dubey, from the Department of Neuromedicine at the Bangur Institute of Neurosciences (BIN) in India, and Julián Benito-León, from the Department of Neurology at Hospital Universitario 12 de Octubre in Madrid explained: “We speculate that there must have been some deleterious effect of COVID-19 in patients with pre-existing dementia by extrapolating our understanding of the cognitive impact of this viral infection in patients without dementia.However, post-COVID-19 assessment of cognitive impairments in patients with pre-existing dementia is difficult due to multiple factors of confusion and biases”.
In addition to finding that all dementia subtypes, regardless of patients’ prior dementia types, behaved like rapidly progressive dementia after COVID-19, the research team found that the line of demarcation between different types of dementia became noticeably blurry after suffering from COVID-19.
Co-investigator Ritwik Ghosh, from the department of General Medicine at Burdwan Medical College and Hospital in India, expressed concern about dementia subtypes. “It is more difficult in the post-COVID-19 era, where the history of this viral infection plays the most important role. Few patients with a history of COVID-19 without pre-existing dementia have similar brain changes phenotypically and imaging-wise that mimic other degenerative and vascular dementias”.
The researchers also found that the characteristics of a particular type of dementia changed after COVID-19, with both degenerative and vascular dementias beginning to behave as a mixed dementia both clinically and radiologically. A rapidly deteriorating and aggressive course was observed in patients with insidious onset, slowly progressive dementia and who were previously cognitively stable.
Cortical atrophy was also evident at subsequent study follow-ups. Coagulopathy involving small vessels and inflammation, which were further correlated with changes in intensity of white matter in the brain, was considered the most important pathogenic indicator.
The rapid progression of dementia, the addition of more deficits/impaired cognitive abilities, and the increase or new appearance of white matter lesions suggest that previously compromised brains have few defenses to resist a new insult (i.e., a “second hit” such as infection or dysregulated immune response and inflammation).
According to Dr. Dubey and his co-investigators, brain fog is an ambiguous terminology with no specific attribution to the spectrum of post-COVID-19 cognitive sequelae. Based on the progression of cognitive deficits and the association with changes in white matter intensity, we propose a new term: ‘FADE-IN MEMORY’ (ie, fatigue, decreased fluency, attention deficit, depression, executive dysfunction). , slower information processing speed, and subcortical MEMORY impairment)”.
Co-investigator Mahua Jana Dubey, from the department of Psychiatry at Berhampur Mental Hospital in India, added: “Among the various psychosocial impacts of COVID-19, cognitive deficits, when accompanied by depression or apathy and fatigue in patients with or without pre-existing dementia, require careful evaluation because it imposes additional stress and burden on caregivers, one of the most important but often neglected issues that can have the potential to impede treatment.”
“As population aging and dementia increase globally, we believe pattern recognition of COVID-19-associated cognitive deficits is urgently needed to distinguish between COVID-19-associated cognitive impairments per se and other types of dementia. This understanding will have a definite impact on future dementia research,” concluded Dr. Souvik Dubey.
“Increasing epidemiological evidence for the association of COVID-19 and AD is the increased risk of AD with COVID-19, and the increase in COVID-19 in patients with AD points to a shared pathogenesis. We clarify this connection by showing that COVID -19 fundamentally alters the course of dementia regardless of cause,” said the editor-in-chief of the Journal of Alzheimer’s Disease.
Source: IOS Press
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