Hospital-Associated Delirium Linked to Worse Cognitive Trajectories
Key Clinical Summary
- A longitudinal cohort study of 3501 adults found that delirium documented within 30 days of hospitalization was associated with increased risk of mild cognitive impairment (MCI) and dementia.
- Delirium was associated with more than 3 times the hazard of incident MCI (adjusted hazard ratio [aHR], 3.67) and more than 5 times the hazard of dementia (aHR, 5.39).
- Delirium was also associated with accelerated cognitive decline during follow-up, including among participants with unimpaired cognition at baseline.
Delirium documented within 30 days of hospitalization was associated with a significantly higher risk of MCI and dementia, according to longitudinal cohort findings published in JAMA Neurology. In those who had experienced delirium, more rapid cognitive decline was also observed during follow-up.
Study Findings
Using data from the Mayo Clinic Study of Aging (MCSA), researchers included participants who experienced 1 or more hospitalization between October 2004 and December 2023 in their analysis. Those with prior dementia or MCI were excluded.
The final cohort included 3501 adults with a median age of 74.1 years, of whom 1676 (47.9%) were female. Overall, 910 participants (26.0%) carried the apolipoprotein E (APOE) ε4 allele.
Researchers used a validated natural language processing algorithm to identify delirium from clinical notes, associated emergency department visits, and follow-up encounters within 30 days after hospitalization.
Participants underwent neuropsychological testing approximately every 15 months, with MCI and dementia diagnoses determined through expert consensus evaluations. Investigators used Cox proportional hazards regression to assess associations with incident cognitive impairment, adjusting for age, sex, education, and APOE ε4 carrier status.
Over a median follow-up of 7.2 years, delirium was documented in 75 participants (2.1%) within 30 days of hospitalization and was associated with a significantly increased hazard of incident MCI (aHR, 3.67; 95% CI, 2.19-6.15) and dementia (aHR, 5.39; 95% CI, 2.94-9.85).
Longitudinal cognitive testing also demonstrated accelerated cognitive decline among participants who experienced delirium compared with those without documented delirium.
Clinical Implications
The associations with incident MCI and dementia remained after adjustment for demographic characteristics, education, and APOE ε4 carrier status, suggesting that delirium provides prognostic information beyond these measured factors.
For clinicians evaluating older adults during and after hospitalization, the findings identify delirium as a potentially important marker of long-term cognitive vulnerability. However, the observational design does not establish that delirium directly causes subsequent cognitive impairment or dementia.
The results also underscore the importance of considering cognitive trajectories beyond the immediate hospitalization period when interpreting the clinical significance of delirium.
Expert Commentary
“These findings underscore delirium as a medical emergency with lasting cognitive consequences,” wrote Allyson K. Palmer, MD, PhD, Division of Hospital Internal Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, and study coauthors.
The authors concluded that “clinicians should prioritize delirium prevention and early management during hospitalization, implement structured postdischarge follow-up, and counsel patients and their families regarding the potential long-term impact of delirium on cognitive health.”
