Investigating the association between cancer and the risk of dementia: Results from the Memento cohort

Abstract

Introduction Studies on the association of cancer and risk of dementia are inconclusive due to result heterogeneity and concerns of survivor bias and unmeasured confounding. Methods This study uses data from the Memento cohort, a French multicenter cohort following persons with either mild or isolated cognitive complaints for a median of 5 years. Illness‐death models (IDMs) were used to estimate transition‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) for incident cancer in relation to dementia from time since study entry. Results The analytical sample (N = 2258) excluded 65 individuals without follow‐up information. At the end of follow‐up, 286 individuals were diagnosed with dementia, 166 with incident cancer, and 95 died. Incident cancer was associated with a reduced risk of dementia (HR = 0.58, 95% CI = 0.35‐0.97), with a corresponding E‐value of 2.84 (lower CI = 1.21). Discussion This study supports a protective relationship between incident cancer and dementia, encouraging further investigations to understand potential underlying mechanisms.

Investigating the association between cancer and dementia risk: a longitudinal cohort study

“…Similar to the results of Ording et al and Sun et al [ 12 , 20 ], the current study found a stronger association between cancer and the risk of ACD and VD compared to AD after further adjustment for other potentially confounding factors besides age and sex. Similar to our results, a recent prospective cohort study showed that cancer was associated with a roughly 42% reduction in risk of dementia and a 55% reduction in risk of AD [ 18 ]. In addition, a study from the Utah Population Database argued that the inverse association between cancer and AD risk arose from bias due to the competing risks of death [ 17 ].…”

“…Model 1 was adjusted for age and sex and model 2 was additionally adjusted for education, socioeconomic status, ApoE4 , BMI, smoking status, alcohol consumption, obesity, hypertension, diabetes, heart failure, and stroke. After adjustment for demographic characteristics (age, sex, education, socioeconomic status), BMI, smoking status, and alcohol consumption were included in model 2, taking into account the established effects on cancer-related mortality [ 18 ]. In addition, ApoE4 and some comorbidities (obesity, hypertension, diabetes, heart failure, and stroke) were also included in model 2 as risk factors for dementia [ 8 , 28 ].…”

“…Several studies have investigated the relationship between cancer and dementia especially AD, yielding inconsistent findings. Some reported inverse associations [ 18 – 20 ], while others revealed positive [ 30 , 31 ] or null connections [ 7 , 28 ]. Our results supported that cancer was related to a lower risk of dementia was consistent with a review of previous experimental studies, prospective cohort studies, and meta-analyses [ 32 ].…”

“…The investigators explored the relationship between incident cancer and dementia by using illness-death models to account for survivor bias. But they cannot investigate differential effects on dementia risk according to cancer type because of the limited cases [ 18 ]. Furthermore, other studies reported similar findings but also had parallel limitations [ 7 , 8 , 10 , 12 , 19 , 20 ].…”

“…Furthermore, other studies reported similar findings but also had parallel limitations [ 7 , 8 , 10 , 12 , 19 , 20 ]. These limitations included relatively short follow-up periods [ 7 , 8 , 19 ], small sample sizes [ 7 , 11 , 18 ], or a lack of information about relevant comorbidities [ 10 , 19 ].…”