Home Medizin Kognitive Defizite nach COVID reichen von 3–6 IQ-Punktverlust

Kognitive Defizite nach COVID reichen von 3–6 IQ-Punktverlust

von NFI Redaktion

Recent study from the United Kingdom provides more clarity on how a SARS-CoV-2 infection can affect cognition and memory, including new data on how long brain fog can persist after the disease has subsided and which cognitive functions are most vulnerable.

In a large community sample, researchers found that individuals who had recovered from COVID-19 exhibited mild cognitive deficits on average up to a year or more after recovering from the acute illness, equivalent to a 3-point IQ loss compared to age-matched individuals who had never had COVID-19.

However, individuals with more severe cases requiring treatment in the intensive care unit of a hospital had cognitive deficits equivalent to a 9-point IQ drop.

„People with persistent symptoms indicative of long COVID had greater cognitive deficits than those whose symptoms had subsided,“ said lead author Adam Hampshire, PhD, from Imperial College London Medical News from Medscape.

The most significant deficits in cognitive tasks were related to memory, logical thinking, and executive function, he added.

„This means that individuals who had COVID-19 performed slower and less accurately on tasks measuring these abilities,“ said Hampshire. „The group with the biggest cognitive deficits were patients who were hospitalized in the ICU for COVID-19.“

The study was published online on February 28 in The New England Journal of Medicine.

Persistent Brain Fog

Cognitive symptoms following a SARS-CoV-2 infection are well-known, but whether objectively measurable cognitive deficits exist and how long they persist remain unclear.

To investigate this, researchers invited 800,000 adults from the REACT study on SARS-CoV-2 transmission in England to perform an online assessment of cognitive function across eight domains.

Overall, 141,583 participants began the cognitive battery by completing at least one task, and 112,964 completed all eight tasks.

Researchers estimated global cognitive scores in participants previously infected with SARS-CoV-2 and whose symptoms persisted for at least 12 weeks, whether resolved or not, and in uninfected participants.

Compared to uninfected adults, those whose COVID-19 illness resolved had a minor cognitive deficit equivalent to a 3-point IQ loss, the researchers found.

Adults with unresolved persistent COVID-19 symptoms had a 6-point IQ loss, and those hospitalized in the ICU had a 9-point IQ loss, consistent with previous cognitive deficits in patients treated in ICU settings, reported the researchers.

Greater cognitive deficits were evident in adults infected with the original SARS-CoV-2 virus or the B.1.1.7 variant at the onset of the pandemic, while peers infected later in the pandemic (e.g., during the Omicron period) showed smaller cognitive deficits. This finding aligns with other studies suggesting that the association between COVID-19-related cognitive deficits weakened over the course of the pandemic, the researchers noted.

They also found that individuals who developed COVID-19 after two or more vaccinations showed better cognitive performance than those who were unvaccinated.

Memory, reasoning, and executive function tasks were among the most sensitive to COVID-19-related cognitive differences, and performance on these tasks varied with illness duration and hospital stay.

Hampshire stated that further research is needed to determine whether the cognitive deficits improve over time.

„The implications of long-term persistence of cognitive deficits and their clinical relevance remain uncertain and require ongoing monitoring,“ he said.

Likely Larger Cognitive Deficits?

These findings „raise concerns, and their broader implications require assessment,“ wrote Ziyad Al-Aly, MD, of Washington University School of Medicine in St. Louis, and Clifford Rosen, MD, of Tufts University School of Medicine in Boston, in an accompanying editorial.

They believe several open questions remain, including the potential functional impacts of a 3-point IQ loss and whether COVID-19-related cognitive deficits lead to a higher risk of dementia later in life.

„A deeper understanding of the biology of cognitive dysfunction following a SARS-CoV-2 infection and how best to prevent and treat it is crucial to address the needs of affected individuals and maintain population cognitive health,“ Al-Aly and Rosen concluded.

Commenting on the study for Medical News from Medscape, Jacqueline Becker, PhD, clinical neuropsychologist and assistant professor of medicine at the Icahn School of Medicine at Mount Sinai in New York City, noted that „an important caveat“ was the use of an online cognitive function assessment tool in the study, so the results should be taken with „a grain of salt.“

„However, it is a large sample, and the results generally align with what we have seen regarding cognitive deficits post-COVID,“ said Becker.

She suggested that this study likely „underestimates“ the extent of cognitive deficits that would appear on validated neuropsychological tests.

In a recent study, Becker and her colleagues examined the frequency of cognitive impairments in 740 COVID-19 patients who had recovered and were treated on an outpatient, emergency, or inpatient basis.

Using validated neuropsychological measures, they found a relatively high frequency of cognitive impairments in patients several months after contracting COVID-19. Impairments in executive functions, processing speed, category fluency, memory encoding, and recall were predominant in hospitalized patients.

Becker noted that in her experience, cognitive abilities typically improve in some patients 12 to 18 months post-COVID infection.

The study was supported by the National Institute for Health and Care Research and UK Research and Innovation, as well as the Department of Health and Social Care in England and the Huo Family Foundation. Disclosures for authors and editors are available on NEJM.org. Becker has no relevant disclosures.

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