Long-term episodic memory alterations and the role of perceived stress in post-COVID-19 condition

Post-COVID-19 condition (PCC) is frequently associated with cognitive impairments, but the integrity of long-term episodic memory remains poorly understood. This study examined immediate, short-term, and very long-term episodic memory in individuals with PCC and evaluated whether emotional disturbances predict long-term recognition outcomes. Forty-one participants (30 PCC; 11 non-PCC) completed a verbal cued-recall task and an immersive virtual reality free-recall object-location memory (OLM) task immediately after learning and the following day. Nine months later, three recognition tasks (verbal, word-list of objects, and visuospatial recognition) and questionnaires assessing anxiety, depression, and perceived stress were administered. PCC participants required significantly longer retrieval times than non-PCC participants in the immediate and delayed OLM trials. Nine months later, PCC participants exhibited significant impairments in verbal cued-recall compared to the immediate and one-day recall trials. Performance on the word-list task was poorer in the PCC group, whereas scores in verbal and visuospatial recognition tasks remained comparable between groups. Emotional symptoms were significantly higher in the PCC group. Exploratory regression analyses suggested a negative association between perceived stress and nine-month visuospatial recognition performance in PCC participants. These preliminary findings suggest a potential vulnerability of very long-term verbal episodic memory in PCC, alongside slowed retrieval processes and heightened emotional distress. The observed association between chronic perceived stress and visuospatial recognition suggests a potential role of stress in very long-term memory performance. Overall, the results highlight the need for long-term cognitive follow-up in PCC and identify perceived stress as a potential factor relevant for long-term recognition of visuospatial information.