COVID-19 and cognitive function: Evidence for increased processing speed variability in COVID-19 survivors and multifaceted impairment with long-COVID symptoms

Abstract

Background There is increasing evidence for cognitive function to be negatively impacted by COVID-19. There is, however, limited research evaluating cognitive function pre- and post-COVID-19 using objective measures. Methods We examined processing speed, attention, working memory, executive function and memory in adults (≤69 years) with a history of COVID-19 (n = 129, none acutely unwell), compared to those with no known history of COVID-19 (n = 93). We also examined cognitive changes in a sub-group of COVID (n = 30) and non-COVID (n = 33) participants, compared to their pre-COVID-19 pandemic level. Results Cross-sectionally, the COVID group showed significantly larger intra-individual variability in processing speed, compared to the non-COVID group. The COVID sub-group also showed significantly larger intra-individual variability in processing speed, compared to their pre-COVID level; no significant change occurred in non-COVID participants over the same time scale. Other cognitive indices were not significantly impacted in the cross-sectional or within-subjects investigations, but participants (n = 20) who had needed hospitalisation due to COVID-19 showed poor attention and executive function relative to those who had not required hospitalisation (n = 109). Poor health and long-COVID symptoms correlated with poor cognitive function across domains in the COVID group. Conclusions The findings indicate a limited cognitive impact of COVID-19 with only intra-individual variability in processing speed being significantly impacted in an adult UK sample. However, those who required hospitalisation due to COVID-19 severity and/or experience long-COVID symptoms display multifaceted cognitive impairment and may benefit from repeated cognitive assessments and remediation efforts.

Cognitive and mental health trajectories of COVID-19: Role of hospitalisation and long-COVID symptoms

“…The sample consists of 138 of 222 adults who had been assessed 6 months earlier (T1; March 2021–March 2022) for our previous study investigating the cognitive impact of COVID-19 in working-age UK adults [ 18 ]. Of 222 participants (129 with and 93 without a history of COVID diagnosis) assessed at T1 [ 18 ], 71 (41 COVID, 30 non-COVID) were lost to the follow-up, and 13 non-COVID (at T1) participants were excluded due to them having tested COVID-19 positive between T1 and T2, leaving 138 participants (mean age: 39.72 ± 11.81) for this investigation (re-assessed at T2; September 2021–October 2022) (see Figure 1 ).…”

“…The sample consists of 138 of 222 adults who had been assessed 6 months earlier (T1; March 2021–March 2022) for our previous study investigating the cognitive impact of COVID-19 in working-age UK adults [ 18 ]. Of 222 participants (129 with and 93 without a history of COVID diagnosis) assessed at T1 [ 18 ], 71 (41 COVID, 30 non-COVID) were lost to the follow-up, and 13 non-COVID (at T1) participants were excluded due to them having tested COVID-19 positive between T1 and T2, leaving 138 participants (mean age: 39.72 ± 11.81) for this investigation (re-assessed at T2; September 2021–October 2022) (see Figure 1 ). Of these 138 participants (current sample), 88 had a history of COVID-19 diagnosis (14 males, 74 females; mean days since diagnosis: 459 ± 180.84; range: 163–895) (to be referred to as the “COVID group”) and 50 had no known history of COVID-19 (11 males, 39 females; to be referred to as the “non-COVID group”).…”

“…The MyCQ mobile application tool (approved by the National Health Service in the UK) assesses processing speed, attention, working memory, executive function, and memory domains, using digital versions of commonly utilised neuropsychological tests validated against the Cambridge Neuropsychological Automated Test Battery [21][22][23]. As described previously [18], Processing Speed was assessed using a simple reaction time (RT) task, Attention using a choice RT task, Working Memory using the 2-back task, Executive Function using the Trail-Making B task, and memory was assessed using a visual recognition memory task (for further details, see Table 1).…”

“…In our recent study [ 18 ] investigating the impact of COVID-19 on cognitive function and mental health in a working-age sample (mean age: 38.70 ± 12.08), we had found a limited cognitive impact of COVID-19 diagnosis, with only intra-individual variability in processing speed being significantly increased in COVID-19 survivors, compared to non-COVID controls. There was, however, multifaceted cognitive impairment in association with long-COVID symptoms.…”

“…Mental health and sleep quality were also worse in COVID-19 survivors, relative to non-COVID controls. Here, with a further assessment (6-month follow-up) of this previously assessed sample [ 18 ], we aimed to examine: (i) the longitudinal impact of COVID-19 on cognitive function, mental health, and sleep, first, on average, and then classified by COVID-19-related hospitalisation; and (ii) changes in long-COVID symptom load and their association with cognitive function, mental health and well-being at 6 months post the initial assessment. Based on previous findings [ 10 – 12 , 14 , 16 , 19 ], we predicted: (i) a change towards normalisation of cognitive function, mental health, and sleep from study entry (T1) [ 18 ] to the 6-month follow-up (T2) assessments, on average, in the COVID group, relative to non-COVID group, and (ii) persistently impaired cognitive function, mental health, and sleep in participants with a history of COVID-19-related hospitalisation and/or ongoing long-COVID symptoms.…”