Abstract

Background: COVID-19 is still a major public health concern. COVID-19 is known to affect the central nervous system (CNS), however, the extent of the cognitive effects of infection are unknown. We developed an online battery for community testing, to learn more about the cognitive effects of infection.
Method: Participants were recruited between October 2020 and December 2021 from social media, and completed objective cognitive-tasks and online health questionnaires using Psytoolkit (Stoet, 2017). Subjective questionnaire measures included fatigue, sleepiness, mood, and cognitive complaints. Objective cognitive tests measured sustained attention; spatial span; and visual short-term memory. Participants self-reported their comorbidities. Prior COVID-19 infection was identified by self-reported positive PCR or lateral flow test. Data was split into age/infection status groups of i) 18-34y positive infection (n=69, mean-age: 21.4 [3.6]); ii) 18-34y negative infection (n=189, mean-age: 22.65 [4.3]); iii) positive infection (n=26, mean-age: 46.9 [7.1]); and iv) 35y+ negative infection (n=68, mean-age: 45.44 [7.56]).
Result: Of 359 participants recruited, 95 (26.4%) reported a prior positive COVID-19 test. We found no differences in demographic variables and any variables of interest between Covid-positive and Covid-negative groups overall. However, within the age/infection status groups, we found:
The 35+ Covid positive group reported higher fatigue (d=0.69) and performed poorer (d=0.66) on a visual short-memory task relative to the 35+ Covid-negative individuals.
Within the overall Covid-positive sample, younger age β=-0.18, p=0.04); higher fatigue (β<0.001) and poorer mood (β=-0.18, p=0.05), were associated with greater perceived cognitive complaints [R2=0.63 (adjusted R2=0.6), F(6,75)=21.1, p <0.001]. Furthermore, a higher number of co-morbidities (β=-0.31, p=0.01) was associated with poorer spatial span [R2=0.25 (adjusted R2=0.19), F(6, 75)=4.23, p=0.001].
Within the overall Covid-negative sample, sleepiness (β=0.32, p<0.001) and higher fatigue (β=0.54, p<0.001) were associated with greater perceived cognitive complaints [R2=0.66 (adjusted R2=0.63), F(6, 65)=20.9, p<0.001]. There were no significant associations with objective cognitive performance within this sample.
Conclusion: COVID-19 infection status was associated with subjective and objective cognitive complaints. Adults aged 35-63 years with prior COVID-19 infection appear to be differentially affected. These data add to the body of evidence indicating there are cognitive consequences from COVID-19 infection.