Brain function impaired in patients following severe Covid-19, but pneumonia, cardiac arrest cause more damage

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Thus, they say that long-term associations with brain health might not be specific to Covid-19 but associated with overall illness severity and hospitalisation.

They also said that this information was important for putting understandable concerns about brain health after Covid-19 into perspective. Their findings are published in the Journal of American Medical Association (JAMA) Network Open titled “Brain Health After COVID-19, Pneumonia, Myocardial Infarction, or Critical Illness”.

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The Covid-19 story

Previous studies have found Covid-19 to compromise brain function.

However, long-term prospective investigations with matched control cohorts and face-to-face assessments were lacking, the researchers said.

In this study, the team included 345 participants, including 120 patients with Covid-19, 125 patients hospitalised for non-Covid-19 pneumonia, myocardial infarction, or non-Covid-19, ICU-requiring illness, and 100 healthy controls.

Over the follow-up period, the participants were evaluated for their cognition and executive function, along with depression and anxiety. They also underwent a neurological examination, which measured their sensorimotor and cerebellar functions and cranial nerves.

The team also conducted interviews with the patients to gather data on cognitive and neuropsychiatric symptoms they were experiencing, including fatigue. The symptoms attributable to the hospitalisation were included in the study, they said.

All the evaluations, except for executive function and impaired sense of smell, showed that patients hospitalised with Covid-19 performed worse than the healthy individuals, but no worse than those hospitalised with similarly severe illnesses, the researchers said.

They also found that patients with Covid-19 had a higher incidence of new psychiatric diagnoses — anxiety and depression — compared with healthy controls, but again, not more than the hospitalised control patients. They said this observation corroborated previous studies.

The researchers acknowledged that because healthy controls had fewer comorbidities than hospitalised individuals, thus multi-morbidity could play a role in both hospitalisation and lasting associations with brain health.

Further, even as studies with broader cognitive test batteries are needed to confirm these findings, brain health after Covid-19 seems overall comparable to that after other diseases of similar severity, they said.

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The evaluation

The main focus of the study was to evaluate overall cognition using SCIP (Screen for Cognitive Impairment in Psychiatry) and MoCA (Montreal Cognitive Assessment) scores. SCIP scores have no upper limit and start at 0, indicating more significant impairment with lower scores. On the other hand, MoCA scores range from 0 to 30, where scores below 26 suggest cognitive impairment.

After an 18-month follow-up, the average SCIP scores were 68.8 for healthy individuals, 59.0 for Covid-19 patients who were hospitalised, and 61.6 for hospitalised individuals without COVID. The average MoCA scores were 28.2 for healthy individuals, 26.5 for hospitalised COVID patients, and 27.2 for hospitalised individuals without Covid-19.

The study also examined secondary outcomes like executive function, anxiety, depressive symptoms, and neurological deficits. Hospitalised Covid-19 patients generally displayed worse secondary outcome scores compared to healthy individuals.

However, these scores were mostly similar between hospitalised Covid-19 patients and those hospitalised for other reasons.

The authors referenced prior studies indicating persistent cognitive impairment in a subset of individuals post-Covid-19, ranging from 12% to 50% even one year after infection. In this study, 38 percent of Covid-19 patients had MoCA scores below 26 at the 18-month follow-up, performing less well in all cognitive tests compared to the healthy population, aligning with earlier research.

The study duration covered different strains of SARS-CoV-2, acknowledging varying virulence and potential long-term effects. Limitations included the relatively small cognitive test battery of the SCIP, and the unavailability of pre-pandemic cognitive scores for comparison.

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