CANCER survivors have a 25% lower risk of developing dementia, according to a large population-based cohort analysis using UK Clinical Practice Research Datalink (CPRD) data.
This study investigated the association between cancer and Alzheimer’s disease and related dementias (ADRD) in over 3 million individuals aged 60 and above, spanning a period of up to 30 years from 1988–2018. The research aimed to explore the reported inverse association between these common conditions of old age and investigate possible causal factors.
The study employed Cox proportional hazards models to estimate hazard ratios (HR) for dementia risk associated with previous cancer diagnosis. Competing risk models were used to account for the competing risk of death. The analysis included 412,903 participants with cancer diagnoses and 230,558 subsequent dementia diagnoses over a median follow-up period of 7.9 years.
After adjusting for potential confounders, cancer survivors showed a significantly lower risk of developing dementia (hazard ratio: 0.75, 95% CI: 0.74–0.76). When accounting for the competing risk of death, the sub-distribution HR was 0.56 (95% CI: 0.55–0.56). These results were consistent across prevalent and incident cancer cases, as well as different common cancer types.
Additionally, a two-sample Mendelian randomisation analysis using 357 cancer-related instrumental single-nucleotide polymorphisms provided evidence of vertical pleiotropy between genetically predicted cancer and reduced risk of Alzheimer’s disease (odds ratio: 0.97, 95% CI: 0.95–0.99).
The findings provide strong epidemiological evidence supporting the inverse association between cancer and ADRD risk, suggesting a potential causal relationship through genetic instruments. This research has important implications for clinical practice, as it may inform risk assessment and screening strategies for dementia in cancer survivors.
Jenna Lorge, EMJ
Reference
Bassil DT et al. Lower incidence of dementia following cancer diagnoses: evidence from a large cohort and mendelian randomization study. JPAD. 2024;11(5):1397-1405.
