High incidence of cognitive deficits, brain fog following COVID-19 infection

Dr Jacqueline Becker from the Division of General Internal Medicine, Icahn School of Medicine at Mount Sinai, New York, and colleagues reported a “relatively high frequency of cognitive impairment several months after patients contracted COVID-19,” which patients have described as brain fog.

Dr Becker, first author of the article, and colleagues investigated the rates of cognitive impairment in a cross-sectional study¹ of survivors of COVID-19 who had been treated in outpatient, accident and emergency services, or inpatient hospital settings and identified through the Mt. Sinai Health System registry. All patients had tested positive for SARS-CoV-2 or had serum antibody positivity and no history of dementia. The study was conducted from April 2020 through May 2021.

The patients’ cognitive functioning was assessed using the following neuropsychological measures: Number Span forward (attention) and backward (working memory), Trail Making Test Part A and Part B (processing speed and executive functioning, respectively), phonemic and category fluency (language), and the Hopkins Verbal Learning Test–Revised (memory encoding, recall, and recognition), the investigators recounted. The impairment on each scale was defined as a z score of ≤1.5 standard deviations below the specific measurements for age, educational level, and sex-adjusted norms.

A total of 740 participants were included in the study (63% women; mean age, 49 years; range, 38-59). More than half of patients were Caucasian (54%), followed by Hispanic (20%), and Black (15%); the rest were multiracial and other (including Asian). The mean time from establishment of the COVID-19 diagnosis was 7.6 months.

The investigators reported the following most prominent cognitive deficits: processing speed (18%, n = 133), executive functioning (16%, n = 118), phonemic fluency (15%, n = 111), and category fluency (20%, n = 148), memory encoding (24%, n = 178), and memory recall (23%, n = 170).

Adjusted analyses showed that “hospitalised patients were more likely to have impairments in attention (odds ratio [OR]: 2.8; 95% confidence interval [CI]: 1.3-5.9), executive functioning (OR: 1.8; 95% CI: 1.0-3.4), category fluency (OR: 3.0; 95% CI: 1.7-5.2), memory encoding (OR: 2.3; 95% CI: 1.3-4.1), and memory recall (OR: 2.2; 95% CI: 1.3-3.8) than those in the outpatient group.”

In contrast, patients treated in the accident and emergency services had impaired category fluency (OR: 1.8; 95% CI: 1.1-3.1) and memory encoding (OR: 1.7; 95% CI: 1.0-3.0) compared with patients treated on an outpatient basis. No significant differences in impairments in other domains were observed between groups.

The investigators noted that the results, i.e., the association of COVID-19 infection with executive functioning, raises questions about long-term treatment and emphasised the importance of future studies to identify the risk factors and mechanisms underlying cognitive dysfunction and rehabilitation options.

Reference

1. Becker JH, Lin JJ, Doernberg M, et al. Assessment of cognitive function in patients after COVID-19 infection. JAMA Netw Open 2021;4(10):e2130645. doi:10.1001/jamanetworkopen.2021.30645