DENVER, July 29, 2021 /PRNewswire/ -- 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® (AAIC®) 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.
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
needed."
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
disease.
"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 (Aβ40, Aβ42) 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 Aβ1-40, but the pTau/Aβ42
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 injury.
"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 impairment.
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 months."
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: www.alz.org/aaic/
AAIC 2021 newsroom: www.alz.org/aaic/pressroom.asp
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®. Visit alz.org or call 800.272.3900.
- Gabriel de Erausquin, MD, PhD,
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; Fundación de Lucha contra los
Trastornos Neurológicos y Psiquiátricos en Minorías (FULTRA);
Zachry Foundation Distinguished Chair of Alzheimer's Clinical Care
and Research; Greehey Family Foundation Distinguished University
Chair of Alzheimer's Research)
- Thomas Wisniewski, PhD, 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, PhD, 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)
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SOURCE Alzheimer’s Association