Cognitive impairment after critical illness: A scoping review of recovery trajectories, assessment practices, and risk factors.

BACKGROUND: Persistent cognitive impairment is an important long-term sequela of critical illness, yet evidence regarding its post-intensive care unit (ICU) trajectories, determinants, and assessment practices remains fragmented.

OBJECTIVES: The aim of this study was to map the literature on persistent post-ICU cognitive impairment among adult survivors of critical illness, with particular attention to recovery trajectories, cognitive assessment practices, associated risk factors, and evidence gaps.

METHODS: A scoping review was conducted following the Joanna Briggs Institute methodology and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines. Cochrane, CINAHL, Embase, MEDLINE, and ClinicalTrials.gov were searched from inception to 20 November 2025. Studies involving adult ICU survivors (aged ≥18 years) reporting postdischarge cognitive outcomes, including persistent post-ICU cognitive impairment, were included. In contrast, studies assessing cognitive dysfunction exclusively during hospitalisation or delirium without postdischarge cognitive assessment were excluded. Data were synthesised using descriptive and evidence-mapping approaches.

RESULTS: Forty-one studies were included, predominantly prospective cohort studies from Europe and North America. Cognitive impairment was most prevalent within the first month after ICU discharge, with substantial heterogeneity in recovery trajectories over time. While partial recovery occurred in some individuals, a considerable proportion experienced persistent impairment at mid- and long-term follow-up. Memory and executive functions were most frequently affected. Associated factors were clustered into six domains: patient vulnerability, ICU-related factors, sedation and treatment exposure, psychological factors, biomarkers/neurobiology, and protective or modifiable factors. Considerable variability existed in cognitive assessment tools and timing, with limited alignment across domains and follow-up phases. Evidence mapping revealed gaps in studies of older adults, low- and middle-income settings, and intervention-based research beyond early recovery.

CONCLUSIONS: Persistent post-ICU cognitive impairment is common and heterogeneous among adult survivors of critical illness, with cognitive deficits often emerging early after ICU discharge and persisting in some survivors. These findings support the conceptualisation of cognitive recovery as a dynamic and multifactorial process influenced by patient vulnerability, critical illness, treatment exposures, and postdischarge factors. Evidence remains limited regarding predictors of prolonged or persistent impairment. Greater standardisation of cognitive assessment and longitudinal and interventional research is needed to characterise recovery trajectories, identify individuals at risk of persistent impairment, and evaluate potentially modifiable targets.