Persistent cognitive slowing in post-COVID patients: longitudinal study over 6 months

Abstract

Background Fatigue is a frequent and one of the most debilitating symptoms in post-COVID syndrome (PCS). Recently, we proposed that fatigue is caused by hypoactivity of the brain’s arousal network and reflected by a reduction of cognitive processing speed. However, it is unclear whether cognitive slowing is revealed by standard neuropsychological tests, represents a selective deficit, and how it develops over time. Objectives This prospective study assesses whether PCS patients show deficits particularly in tests relying on processing speed and provides the first longitudinal assessment focusing on processing speed in PCS patients. Methods Eighty-eight PCS patients with cognitive complaints and 50 matched healthy controls underwent neuropsychological assessment. Seventy-seven patients were subsequently assessed at 6-month follow-up. The Test for Attentional Performance measured tonic alertness as primary study outcome and additional attentional functions. The Neuropsychological Assessment Battery evaluated all key cognitive domains. Results Patients showed cognitive slowing indicated by longer reaction times compared to control participants (r = 0.51, p < 0.001) in a simple-response tonic alertness task and in all more complex tasks requiring speeded performance. Reduced alertness correlated with higher fatigue (r = − 0.408, p < 0.001). Alertness dysfunction remained unchanged at 6-month follow-up (p = 0.240) and the same was true for most attention tasks and cognitive domains. Conclusion Hypoarousal is a core deficit in PCS which becomes evident as a selective decrease of processing speed observed in standard neuropsychological tests. This core deficit persists without any signs of amelioration over a 6-month period of time.

Cognitive decline in post-COVID-19 syndrome does not correspond with persisting neuronal or astrocytic damage

“…Limitations of our study are the lack of sequential biomarker and neuropsychological assessments. While there is data showing improvement of cognitive deficits over time, other cohorts found a persisting decrease of processing speed over a 6-month period 34 , 35 .To provide further longitudinal neuropsychological testing in PCS, some participants of our cohort from the study centre in Cologne were evaluated in neuropsychological follow ups. Due to ongoing analyses, results of these follow ups will be published separately.…”

Long COVID is associated with severe cognitive slowing: a multicentre cross-sectional study

“…found a persistent deficit in perceptual processing speed in patients with PCC with cognitive complaints. 10 , 31 …”