Associations between cancer and Alzheimer's disease in a U.S. Medicare population

Freedman, D. Michal; Wu, Jincao; Chen, Honglei; Kuncl, Ralph W.; Enewold, Lindsey; Engels, Eric A.; Freedman, Neal D.; Pfeiffer, Ruth M.

doi:10.1002/cam4.850

Cited by 70 publications

(84 citation statements)

References 40 publications

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“…[2, 4, 13, 14] However, our results showed that incident and prevalent cancers should not be combined into a single “any cancer” group because they have different associations AD and dementia. We are only aware of two prior studies that limited analyses to prevalent cancers.…”

Section: Discussionmentioning

confidence: 97%

Risk of Alzheimer's disease or dementia following a cancer diagnosis

et al. 2017

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ObjectiveWe evaluated dementia and Alzheimer’s disease (AD) risks after a cancer diagnosis in a population-based prospective cohort, the Adult Changes in Thought (ACT) study.MethodsWe followed community-dwelling people aged ≥65 years without dementia at study entry for incident dementia and AD from 1994–2015. We linked study data with cancer registry data and categorized cancer diagnoses as prevalent (diagnosed before ACT study enrollment) or incident (diagnosed during follow-up). We used Cox regression to estimate cause-specific hazard ratios (HRs) with 95% confidence intervals (CIs) for dementia or AD risk comparing people with a cancer diagnosis to people without cancer. We conducted sensitivity analyses restricted to people surviving beyond age 80, and stratified by cancer stage, type, and whether the cancer was smoking-related.ResultsAmong 4,357 people, 756 (17.4%) had prevalent cancer; 583 (13.4%) developed incident cancer, 1,091 (25.0%) developed dementia, and 877 (20.1%) developed AD over a median 6.4 years (34,482 total person-years) of follow-up. Among complete cases (no missing covariates) with at least one follow-up assessment, adjusted HRs for dementia following prevalent and incident cancer diagnoses were 0.92 (95%CI: 0.76, 1.11) and 0.87 (95%CI: 0.64, 1.04), compared to no cancer history. HRs for AD were 0.95 (95%CI: 0.77, 1.17) for prevalent cancer and 0.73 (95%CI: 0.55, 0.96) for incident cancer. In sensitivity analyses, prevalent late-stage cancers were associated with reduced risks of dementia (HR = 0.51, 95%CI: 0.30, 0.89) and AD (HR = 0.50, 95%CI: 0.27, 0.94). When limited to people who survived beyond age 80, incident cancers were still associated with reduced AD risk (HR = 0.69, 95%CI: 0.51, 0.92).ConclusionsOur results do not support an inverse association between prevalent cancer diagnoses, which were primarily early-stage, less aggressive cancers, and risk of dementia or AD. A reduced risk of AD following an incident cancer diagnosis is biologically plausible but may reflect selective mortality.

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Section: Discussionmentioning

confidence: 97%

Risk of Alzheimer's disease or dementia following a cancer diagnosis

et al. 2017

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“…Interestingly, multiple studies suggest an inverse association between cancer and dementia, in particular for Alzheimer disease (AD) . In 1990, Yamada et al investigated risk factors for dementia in atomic‐bomb survivors and observed that the odds of having cancer prior to AD was 70% lower in patients with AD compared to persons without AD.…”

Section: The Risk Of Cancer In Dementia Patients and The Risk Of Demementioning

confidence: 99%

“…Few studies investigated the relation of cancer with other diseases including stroke, automobile injuries, osteoarthritis and macular degeneration, which were used as negative control diseases . In case of survival bias, cancer patients would also have a decreased risk of these diseases.…”

Section: The Risk Of Cancer In Dementia Patients and The Risk Of Demementioning

confidence: 99%

“…Furthermore, several studies investigated the risk of dementia in relation to different cancer sites or stages . Tumours originated deep in the body may progress over a longer time until they become clinically manifest, compared to tumours located at the body surface.…”

Section: The Risk Of Cancer In Dementia Patients and The Risk Of Demementioning

confidence: 99%

“…A substantial body of literature suggests a link between cancer and dementia, that is patients with dementia have a decreased risk of subsequently being diagnosed with cancer, and cancer patients have a lower risk of dementia . Importantly, this association is not restricted to cancer of the central nervous system (CNS) or to long‐term adverse effects of cancer treatments.…”

Section: Introductionmentioning

confidence: 99%

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Cancer and dementia: Two sides of the same coin?

Willik

Schagen

Ikram

2018

Eur J Clin Investigation

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Noncentral nervous system cancer and the brain share an interesting and complex relation, with an emerging body of evidence showing that cancer patients are at an increased risk of developing cognitive problems. In contrast, population‐based studies consistently find an inverse link between cancer and dementia, that is patients with dementia having a lower risk of subsequently developing cancer, and cancer patients being less often diagnosed with dementia. Different biological processes such as inversely activated cell proliferation and survival pathways have been suggested to have an important role underlying this inverse association. However, the effect of methodological biases including surveillance or survival bias has not been completely ruled out, calling into question the inverse direction of the association between cancer and dementia. In fact, emerging evidence now suggests that cancer and dementia might share a positive association. This narrative review summarises the current literature on cancer, cognitive problems and dementia. Moreover, different strategies will be discussed to reduce the impact of potential methodological biases on the association between cancer and dementia, trying to reveal the true direction of this link.

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