Cognitive features of Long COVID following mild infection

Abstract

Aim Concerns regarding long-term cognitive consequences of COVID-19 are growing, with ‘brain fog’ one of the most common yet least understood symptoms of post-COVID condition (PCC). This exploratory study aimed to examine the neurocognitive characteristics of PCC and explore factors associated with any cognitive features.

Methods Adults with neurological concerns were prospectively recruited from an outpatient PCC rehabilitation clinic in Melbourne, Australia. Participants underwent mood and fatigue screening and formal neuropsychological testing.

Results 26 adults participated in this study, on average 11.4±4.7 months post-acute COVID-19 infection. Most were non-hospitalised (88%), middle-aged (M = 45.2 ±14.1) females (92%), vaccinated before infection (88%). They largely screened positive for depression (58%), anxiety (46%), self-reported subjective cognitive concern (78%), and fatigue (53%). Group-level deficits in processing speed, attention, memory, language, visuoconstructional, and executive function emerged when comparing performance to the sample’s estimated ‘High Average’ pre-infection baseline but not when compared to ‘Average’-level population norms. At an individual level, slowed processing speed was the most common cognitive reduction (65%). Self-reported cognitive concerns correlated with reduced performance on language measures, but not fatigue, depression, or anxiety. There were no significant predictors of objective cognitive functioning.

Conclusion The neuropsychological profile of PCC may take the form of subtle cognitive inefficiency compared to estimated premorbid levels, particularly in cases of mild infection. Post-viral mental health and fatigue also emerge as significant issues in this population, underscoring the need for improved clinical awareness and treatment.

Impact This research provides world-first insights into the cognitive features of Long COVID in an Australian population, unique for its high vaccination rates and base population health, and comparatively low Alpha and Delta variant infections. Our findings explain why many studies of Long COVID show “normal” cognitive performances despite persistent cognitive complaints from patients, validating their experience and countering a narrative that these experiences are exclusively related to poor mental health.