Evidence of link between common infections and post-stroke dementia

  • Morton CE & al.
  • Clin Epidemiol
  • 1 Jan 2020

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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  • This study found evidence of an association between common infections and post-stroke dementia in a large cohort of UK stroke survivors.
  • The association was strongest in the 3-12 months following stroke.

Why this matters

  • Better understanding of the association between infections and post-stroke dementia will help to inform the development and targeting of interventions to prevent and treat infections and preserve cognitive function post-stroke.

Study design

  • This population-based cohort study included 60,392 stroke survivors (51.2% male, median age, 74.3 years) with no history of dementia using data from the Clinical Practice Research Datalink (CPRD).
  • Primary exposure was any general practitioners (GP)-recorded infection (lower respiratory tract infection, urinary tract infection, and skin and soft tissue infections requiring antibiotics) after stroke.
  • Primary outcome: incident of all-cause dementia.
  • Funding: Wellcome Intermediate Clinical Fellowship.

Key results

  • A total of 44,057 GP-recorded infections after stroke were recorded among 20,969 (34.7%) patients (median, 2 infections per person [interquartile range, 1-3]).
  • Overall, 4512 (7.5%) patients developed dementia 3 months to 5 years post-stroke
    • 1406 (31.2%) developed early dementia (rate, 35.13 per 1000 person-years at risk [PYAR]; 95% CI, 33.34-37.02); and
    • 3106 (68.8%) developed late dementia (rate, 25.80 per 1000 PYAR; 95% CI, 24.91-26.72).
  • The risk of early post-stroke dementia (3 months to 1 year) was greater in those with ≥1 GP-recorded infection (HR, 1.44; 95% CI, 1.21-1.71).
  • Effect estimates were higher when hospitalised infections were included either as a primary diagnosis (HR, 1.79; 95% CI, 1.52-2.11) or as any diagnosis (HR, 1.84; 95% CI, 1.58-2.14).
  • Late post-stroke dementia (1-5 years) was associated with hospitalised infection (as primary diagnosis; HR, 1.36; 95% CI, 1.23-1.50) but not with GP-recorded infections (HR, 1.05; 95% CI, 0.96-1.16).


  • Study did not assess the severity and location of stroke, which may be predictors of infection and are linked to dementia risk.