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Friday, July 30 2021 - 05:00
COVID-19 Associated With Long-Term Cognitive Dysfunction, Acceleration Of Alzheimer's Symptoms
DENVER, July 30, 2021 /PRNewswire-AsiaNet/ --

Much has been learned about SARS-CoV-2, the virus that causes the novel 
coronavirus, since the beginning of the COVID-19 pandemic. However, questions 
remain about the long-term impact of the virus on our bodies and brains. New 
research reported at the Alzheimer's Association International Conference(R) 
(AAIC(R)) 2021 ( 
), held virtually and in Denver found associations between COVID-19 and 
persistent cognitive deficits, including the acceleration of Alzheimer's 
disease pathology and symptoms.

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In addition to the respiratory and gastrointestinal symptoms that accompany 
COVID-19, many people with the virus experience short- and/or long-term 
neuropsychiatric symptoms, including loss of smell and taste, and cognitive and 
attention deficits, known as "brain fog." For some, these neurological symptoms 
persist, and researchers are working to understand the mechanisms by which this 
brain dysfunction occurs, and what that means for cognitive health long term. 

Scientific leaders, including the Alzheimer's Association and representatives 
from nearly 40 countries -- with technical guidance from the World Health 
Organization (WHO) -- are part of an international, multidisciplinary 
consortium ( 
) to collect and evaluate the long-term consequences of COVID-19 on the central 
nervous system, as well as the differences across countries. Initial findings 
from this consortium presented at AAIC 2021 from Greece and Argentina suggest 
older adults frequently suffer persistent cognitive impairment, including 
persistent lack of smell, after recovery from SARS-CoV-2 infection.

Other key results reported at AAIC 2021 include:

    - Biological markers of brain injury, neuroinflammation and Alzheimer's 
      correlate strongly with the presence of neurological symptoms in 
      COVID-19 patients. 
    - Individuals experiencing cognitive decline post-COVID-19 infection 
      were more likely to have low blood oxygen following brief physical 
      exertion as well as poor overall physical condition.

"These new data point to disturbing trends showing COVID-19 infections leading 
to lasting cognitive impairment and even Alzheimer's symptoms," said Heather M. 
Snyder, Ph.D., Alzheimer's Association vice president of medical and scientific 
relations. "With more than 190 million cases and nearly 4 million deaths 
worldwide, COVID-19 has devastated the entire world. It is imperative that we 
continue to study what this virus is doing to our bodies and brains. The 
Alzheimer's Association and its partners are leading, but more research is 

Cognitive Impairment Correlates with Persistent Loss of Smell in Recovered 
COVID-19 Patients
Gabriel de Erausquin, M.D., Ph.D., M.Sc., of the University of Texas Health 
Science Center at San Antonio Long School of Medicine, along with colleagues 
from the Alzheimer's Association-led global SARS-CoV-2 consortium ( 
), studied cognition and olfactory senses in a cohort of nearly 300 older adult 
Amerindians from Argentina who had COVID-19.

Participants were studied between three and six months after COVID-19 
infection. More than half showed persistent problems with forgetfulness, and 
roughly one in four had additional problems with cognition including language 
and executive dysfunction. These difficulties were associated with persistent 
problems in smell function, but not with the severity of the original COVID-19 

"We're starting to see clear connections between COVID-19 and problems with 
cognition months after infection," said Erausquin. "It's imperative we continue 
to study this population, and others around the world, for a longer period of 
time to further understand the long-term neurological impacts of COVID-19."

COVID-19 Infection Associated with Uptick in Alzheimer's Biomarkers in the Blood
Certain biological markers in blood -- including total tau (t-tau), 
neurofilament light (NfL), glial fibrillary acid protein (GFAP), ubiquitin 
carboxyl-terminal hydrolase L1 (UCH-L1), and species of amyloid beta (AB40, 
AB42) and phosphorylated tau (pTau-181) -- are indicators of injury in the 
brain, neuroinflammation and Alzheimer's disease. 

To study the presence of these blood biomarkers, neurodegeneration and 
neuroinflammation in older patients who were hospitalized with COVID-19, Thomas 
Wisniewski, M.D., a professor of neurology, pathology and psychiatry at New 
York University Grossman School of Medicine, and colleagues took plasma samples 
from 310 patients who were admitted to New York University Langone Health with 
COVID-19. Of the patients, 158 were positive for SARS-CoV-2 with neurological 
symptoms and 152 were positive for SARS-CoV-2 without neurologic symptoms. The 
most common neurological symptom was confusion due to toxic-metabolic 
encephalopathy (TME). 

In patients who were initially cognitively normal with and without TME related 
to COVID-19 infection, the researchers found higher levels of t-tau, NfL, GFAP, 
pTau 181, and UCH-L1 in COVID-19 patients with TME compared to COVID-19 
patients without TME. There were no significant differences with AB1-40, but 
the pTau/AB42 ratio showed significant differences in patients with TME. 
Additionally, t-tau, NfL, UCHL1, and GFAP significantly correlated with markers 
of inflammation such as C-reactive peptide, which may suggest 
inflammation-related blood-brain barrier disruption accompanying neuronal/glial 

"These findings suggest that patients who had COVID-19 may have an acceleration 
of Alzheimer's-related symptoms and pathology," said Wisniewski. "However, more 
longitudinal research is needed to study how these biomarkers impact cognition 
in individuals who had COVID-19 in the long term."

Individuals Recovered from COVID-19 Who Experience Cognitive Decline More 
Likely to Have Poor Physical Condition, Low Oxygen Saturation
George Vavougios, M.D., Ph.D., postdoctoral researcher for the University of 
Thessaly (UTH), and colleagues studied cognitive impairment and related health 
measures in 32 previously hospitalized mild to moderate COVID-19 patients two 
months after discharge from the hospital. Among them, 56.2% presented with 
cognitive decline. Short-term memory impairments and multidomain impairment 
without short-term memory deficits were the predominant patterns of cognitive 

Worse cognitive test scores correlated with higher age, waist circumference and 
waist-to-hip ratio. After adjusting for age and sex, worse memory and thinking 
scores were independently associated with lower levels of oxygen saturation 
during the 6-minute walk test, which is commonly used to assess the functional 
capacity of people with cardiopulmonary disease.

"A brain deprived of oxygen is not healthy, and persistent deprivation may very 
well contribute to cognitive difficulties," said Vavougios. "These data suggest 
some common biological mechanisms between COVID-19's dyscognitive spectrum and 
post-COVID-19 fatigue that have been anecdotally reported over the last several 

This cohort is also part of the global SARS-CoV-2 consortium.

About the Alzheimer's Association International Conference (AAIC)
The Alzheimer's Association International Conference (AAIC) is the world's 
largest gathering of researchers from around the world focused on Alzheimer's 
and other dementias. As a part of the Alzheimer's Association's research 
program, AAIC serves as a catalyst for generating new knowledge about dementia 
and fostering a vital, collegial research community.
AAIC 2021 home page:
AAIC 2021 newsroom:
AAIC 2021 hashtag: #AAIC21

About the Alzheimer's Association
The Alzheimer's Association is a worldwide voluntary health organization 
dedicated to Alzheimer's care, support and research. Our mission is to lead  
the way to end Alzheimer's and all other dementia -- by accelerating global 
research, driving risk reduction and early detection, and maximizing quality 
care and support. Our vision is a world without Alzheimer's and all other 
dementia(R). Visit: ( 
) or call +1-800.272.3900.

    - Gabriel de Erausquin, M.D., Ph.D., MSc., et al. Olfactory dysfunction 
      and chronic cognitive impairment following SARS-CoV-2 infection in a
      sample of older adults from the Andes mountains of Argentina.
      (Funder(s): Alzheimer's Association; Fundacion de Lucha contra los
      Trastornos Neurol¨®gicos y Psiquiatricos en Minorias (FULTRA); Zachry
      Foundation Distinguished Chair of Alzheimer's Clinical Care and 
      Research; Greehey Family Foundation Distinguished University Chair of   
      Alzheimer's Research) 
    - Thomas Wisniewski, Ph.D., et al. Plasma Biomarkers of Neurodegeneration 
      and Neuroinflammation in Hospitalized COVID-19 Patients with and 
      without New Neurological Symptoms (Funder(s): National Institutes of 
      Health/National Institute on Aging) 
    - George Vavougios, MD, Ph.D., et al. Investigating the prevalence of 
      cognitive impairment in mild and moderate COVID-19 patients two months 
      post-discharge: associations with physical fitness and respiratory 
      function. (Funder(s): 2020 National Strategic Reference Framework 
      (NSRF) Scholarship)

SOURCE:  Alzheimer¡¯s Association

CONTACT: Alzheimer's Association Media Line
         AAIC 2021 Press Office