By Lisa Ravdin, PhD
Associate Professor of Neuropsychology and Director of the Weill Cornell Neuropsychology Service, Department of Neurology & Neuroscience, New York Presbyterian Hospital/Weill Cornell Medical Center
SYNOPSIS: Hospitalized COVID-19 patients with cognitive complaints demonstrate reduced attention and executive dysfunction on formal cognitive testing consistent with the same frequency and pattern of cognitive changes associated with critical illness.
SOURCE: Jaywant A, Vanderlind WM, Alexopoulos GS, et al. Frequency and profile of objective cognitive deficits in hospitalized patients recovering from COVID-19. Neuropsychopharmacology 2021; Feb 15:1-6. doi.org/10.1038/s41386-021-00978-8. [Online ahead of print].
In 2020, hospital settings in pandemic hotspots became real-time clinical laboratories for studying the evolving knowledge of the effects of COVID-19 infection. Among the variety of symptoms associated with COVID-19, central nervous system (CNS) manifestations include headaches, dizziness, delirium, encephalopathy, and stroke. Cognitive complaints also have been reported in COVID-19 patients, yet there have been limited formal studies that incorporate objective cognitive measures to understand the nature of these complaints.
Jaywant and colleagues sought to examine cognitive function in patients who underwent prolonged hospitalization for COVID-19 using objective cognitive measures. Subjects consisted of 57 individuals hospitalized for acute COVID-19 symptoms who also had suspected cognitive dysfunction. Participants were medically stable yet experiencing some form of impairment in mobility or activities of daily living that necessitated acute inpatient rehabilitation prior to discharge.
Cognitive testing consisted of bedside administration of the Brief Memory and Executive Test (BMET), a paper and pencil measure that consists of multiple subtests of memory and executive function, including orientation, five-word immediate recall (working memory), five-word recall (delayed memory), five-word recognition (delayed recognition), rapid letter-number matching (divided attention), motor speed, rapid letter sequencing (visual attention and processing speed), and letter-number switching (mental set-shifting). Scores from the short form of the Activity Measure for Post-Acute Care closest to the time of admission to rehabilitation were collected to assess functional status. Impairment ratings were defined according to age-corrected normative data, with scores < 1 standard deviation (SD) below the mean interpreted as mild/borderline impaired and scores < 2 SD below the mean classified as impaired. Pearson correlations and Chi square analyses were used to examine relationships between cognition and patient variables.
Impairment ratings reflecting mild cognitive impairment were a frequent finding (81%) in this sample of hospitalized COVID-19 patients, with deficits primarily on tasks of complex attention. In terms of memory, working memory (immediate recall) was affected more frequently as opposed to delayed recall, consistent with the pattern often observed in the context of compromised complex attention. The presence of cognitive deficits was not associated with the length of intubation, the time between extubation and assessment, or the presence of psychiatric symptoms. There was no significant association between cognition and preexisting cardiometabolic diagnosis, and the relationship between delirium and cognitive deficits was not statistically significant.
Jaywant et al expeditiously conducted this study early on at the height of the pandemic in the hotspot of New York City. They provided valuable descriptive information to inform our knowledge of the frequency and pattern of cognitive changes observed in hospitalized COVID-19 patients. The results are consistent with the literature on the rates of cognitive deficits in hospitalized critical care patients, with comparable numbers of patients (approximately 80%) experiencing some form of cognitive dysfunction.
These preliminary data on COVID-19 patients set the stage for empirically designed controlled investigations that can explore the causation of cognitive changes over and beyond those that might be attributable to critical illness hospitalization. The literature suggests hospitalized critically ill patients tend to demonstrate the most significant cognitive deficits at or around the time of discharge, and this can persist for months to years after hospitalization. As in this study, often this occurs in the absence of pre-hospitalization cognitive impairment.
Cognitive complaints also have been reported anecdotally in individuals with much milder symptom presentations of COVID-19 that do not require hospitalization, and this often is described by patients as “brain fog.” Studies investigating cognition post-COVID-19 infection should consider that cognitive complaints present at an unprecedented time during a pandemic where factors such as social isolation and change in work routines and daily activities as well as in sleep and mood typically are affected.
In those who have survived the more significant physical effects of infection, the emotional response to serious medical illness also may affect the persistence of post-hospitalization symptoms. Consideration of these potential contributing factors to cognitive complaints can help guide intervention and treatment recommendations.