Topline
High numbers of Covid-19 patients show impaired cognitive functioning months after diagnosis, according to a study published Friday in JAMA Network Open, shedding light on “brain fog,” a common complaint among the many survivors experiencing ‘long Covid’—lingering coronavirus symptoms months after infection.
Many Covid-19 survivors complain of cognitive difficulties.
Key Facts
A series of cognitive tests revealed high levels of cognitive impairment among 740 Covid-19 patients months after they had been diagnosed with Covid-19 (the average time between diagnosis and assessment was 7.6 months), according to the peer reviewed study, affecting up to one in four patients in some instances.
Nearly a quarter of participants had difficulty processing (24%)or retrieving (23%) memories, the researchers found, while around a fifth showed slower mental processing speeds (18%) and impaired language.
Compared to outpatients, impairments were more frequent among patients who were admitted for inpatient hospital care or treated in the emergency department, respectively 3 and 1.8 times more likely to show impaired language, 2.3 and 1.7 times more likely to have impaired memory encoding and 2.2 and 1.5 times more likely to have impaired memory retrieval.
Memory recognition—the ability to recognize previously-encountered things—was relatively spared compared to encoding and retrieval, something the researchers said indicates a problem with executive function, the type of higher-level mental skills involved in planning, organizing and regulating behavior.
While it’s known that older adults are more susceptible to cognitive impairment following severe illness, the researchers said the study’s relatively young cohort (the average age was 49) suggests the impairment is linked to Covid-19 specifically, a finding in line with research on other viruses like flu and early reports from Covid-19 patients.
High levels of executive dysfunction following Covid-19 infection have “considerable implications” for long-term treatment, the researchers said, and needs further study to assess the future impact of infection and to discover how the virus affects the brain.
Tangent
While all groups studied showed higher rates of cognitive dysfunction, hospitalized patients and those treated in the emergency department had markedly higher rates of impairment in tests examining executive function, the researchers found. Of the outpatients tested, 12% showed impairment in memory recall, 16% memory encoding and 13% category fluency (a language test widely used as a test for executive function). In patients treated in the ED, 23%, 26% and 21% showed impairments in those categories, respectively. Among hospitalized patients, 39%, 37% and 35% had impaired functioning. Hospitalized patients were also 2.8 times more likely to have attention impairments compared to outpatients. The finding underscores the importance of vaccination. Though not able to prevent all coronavirus infections, vaccination drastically cuts the odds of severe illness and hospitalization in rare breakthrough cases. The researchers do not state whether study subjects had been vaccinated.
Key Background
While many patients complain of impaired cognition after Covid-19 infection—often called “brain fog”—there have been few studies to thoroughly vet these claims with standard cognitive tests and large sample sizes. Brain fog is not a precise clinical term, nor unique to Covid-19, and refers to a kind of mental sluggishness and lack of focus. It, or symptoms aligned with it, is one of the most commonly reported symptoms of long Covid, the lingering and debilitating illness that can affect patients for months or years after infection. Symptoms can affect the entire body and many affect the nervous system or mental health. Research suggests that one in five Covid-19 patients will go on to be diagnosed with a mental illness within three months of recovery and conditions affecting the brain and thinking are common in those suffering from long Covid.
Further Reading
‘I Feel Like I Have Dementia’: Brain Fog Plagues Covid Survivors (NYT)
Assessment of Cognitive Function in Patients After COVID-19 Infection (JAMA Network Open)
Even Mild Cases of COVID May Leave a Mark on the Brain (The Conversation)
Vaccines Slash Risk Of Long Covid From Breakthrough Infections, Study Finds (Forbes)
Here’s What We Know About Long Covid, The Debilitating, Lingering Illness That Could Affect Millions (Forbes)
A Tsunami of Disability Is Coming as a Result of ‘Long COVID’ (Scientific American)
