- Delirium was associated with a new diagnosis of dementia and cognitive decline, independent of baseline cognition and illness severity.
- Repeated episodes of delirium, more days with delirium, and more severe delirium were associated with worse cognitive outcomes.
Why this matters
- Findings suggest that delirium is a potentially modifiable risk factor for dementia.
- The Delirium and Cognitive Impact in Dementia (DECIDE) study included participants (aged, ≥65 years) with (n=82) or without delirium (n=123) from the Cognitive Function and Ageing Study II (CFAS-II).
- Primary outcomes: dementia status and Mini-Mental State Examination (MMSE) score at 12 months after hospital discharge in comparison with baseline cognitive function from CFAS-II.
- Funding: Clinical Research Fellowship from the Alzheimer’s Society.
- 135 (65.9%) participants completed follow-up interviews 1 year after hospital admission; 18 received a new diagnosis of dementia and 38 had died.
- An episode of delirium was associated with an increased risk of incident dementia, independent of illness severity and baseline cognition (OR, 8.8; 95% CI, 1.9-41.4; P=.006).
- Delirium independently predicted a decline in MMSE score at follow-up interview (β, −1.8 points; 95% CI, −3.5 to −0.2; P=.030).
- The risk of incident dementia was greater with >1 episode of delirium (OR, 13.9; 95% CI, 1.3-151.0; P=.031) vs single episode (OR, 8.6; 95% CI, 1.8-41.1; P=.007).
- Having delirium for >5 days was independently associated with lower MMSE scores (β, −5.1 points; 95% CI, −8.1 to 2.1; P=.001) vs 1-5 days (β, −1.7 points; 95% CI, −3.4 to 0.1; P=.044).
- More severe delirium was linked with lower MMSE scores (β, −0.4 points [95% CI, −0.6 to −0.2]; P=.001) and incident dementia (OR, 1.3; 95% CI, 1.1-1.5; P=.012).
- Variation in time that had elapsed between baseline and follow-up cognitive assessments.