Chronic post-COVID neuropsychiatric symptoms persisting more than 1 year after infection during the 'Omicron wave'.

Background: The heterogeneity of chronic post-COVID neuropsychiatric symptoms (PCNPS), especially after infection by the Omicron strain, has not been adequately explored.

Aims: To explore the clustering pattern of chronic PCNPS in a cohort of patients having their first COVID infection during the 'Omicron wave' and discover phenotypes of patients based on their symptoms' patterns using a pre-registered protocol.

Method: We assessed 1205 eligible subjects in Hong Kong using app-based questionnaires and cognitive tasks.

Results: Partial network analysis of chronic PCNPS in this cohort produced two major symptom clusters (cognitive complaint-fatigue and anxiety-depression) and a minor headache-dizziness cluster, like our pre-Omicron cohort. Participants with high numbers of symptoms could be further grouped into two distinct phenotypes: a cognitive complaint-fatigue predominant phenotype and another with symptoms across multiple clusters. Multiple logistic regression showed that both phenotypes were predicted by the level of pre-infection deprivation (adjusted P-values of 0.025 and 0.0054, respectively). The severity of acute COVID (adjusted P = 0.023) and the number of pre-existing medical conditions predicted only the cognitive complaint-fatigue predominant phenotype (adjusted P = 0.003), and past suicidal ideas predicted only the symptoms across multiple clusters phenotype (adjusted P < 0.001). Pre-infection vaccination status did not predict either phenotype.

Conclusions: Our findings suggest that we should pursue a phenotype-driven approach with holistic biopsychosocial perspectives in disentangling the heterogeneity under the umbrella of chronic PCNPS. Management of patients complaining of chronic PCNPS should be stratified according to their phenotypes. Clinicians should recognise that depression and anxiety cannot explain all chronic post-COVID cognitive symptoms.