Summary: People with dementia who had a prior cancer diagnosis show better cognitive function at the time of dementia diagnosis and tend to decline more slowly than those without a cancer history.
Source: University of Alabama at Birmingham
As people age, the risk of developing cancer or dementia increases. Both conditions share common risk factors—such as hypertension and diabetes—and many cancer patients experience treatment-related cognitive impairment with symptoms that can resemble dementia.
But do these overlaps imply that a cancer diagnosis changes the risk or course of dementia? Previous studies have reported an inverse association between cancer and dementia risk, yet long-term data on how prior cancer affects the progression of dementia are limited.
Mackenzie Fowler, Ph.D., in work completed for her dissertation at the University of Alabama at Birmingham School of Public Health, conducted a retrospective, longitudinal analysis to clarify the long-term relationship between prior cancer and dementia progression.
Published in the Journal of Alzheimer’s Disease, the study found that people with dementia who had a history of cancer demonstrated higher cognitive performance at the time of dementia diagnosis and showed similar or slightly slower cognitive decline over time compared with dementia patients who had never had cancer.
“Our findings suggest that, even over many years, only about 20% of people with cancer go on to receive a dementia diagnosis after their cancer diagnosis,” Fowler said. “Among those who do develop dementia, cognitive performance at diagnosis and during follow-up was generally better than in dementia patients without a prior cancer diagnosis.” Fowler is currently a postdoctoral scholar trainee in the UAB Division of Hematology and Oncology, Marnix E. Heersink School of Medicine.
The study results indicate a nuanced relationship depending on cancer history. Participants with a single prior cancer diagnosis had on average a roughly 1.1-point higher cognitive baseline score and appeared to progress slightly more slowly than those without cancer. Conversely, participants with two or more prior cancer diagnoses had about a 1.5-point lower cognitive score at baseline compared with those without a cancer history.
To reach these conclusions, Fowler and colleagues analyzed electronic health record data spanning July 2003 through February 2020 from a single academic medical center. They identified 3,809 patients with dementia, of whom 672 (17.6%) had a recorded history of cancer prior to their dementia diagnosis. Cognitive function was assessed using the Alabama Brief Cognitive Screener (ABCs), and cognitive trajectories were modeled using adjusted linear mixed effects models to estimate baseline cognition and rate of decline by cancer history, with additional comparisons across race and ethnicity.
Because the analysis drew on clinical records over many years, researchers were able to observe differences across demographic groups. Independent of cancer history, underrepresented racial and ethnic groups—particularly non-Hispanic Black patients—had lower cognitive scores at baseline and throughout follow-up compared with non-Hispanic White patients and other race/ethnicity groups. This finding highlights persistent disparities in dementia outcomes that are not explained solely by prior cancer status.
Fowler emphasized several important caveats. The study could not distinguish dementia or cancer by specific subtypes or stages, and all participants were drawn from one hospital system. These factors limit generalizability. The researchers also noted that smoking and comorbidities attenuated the observed association between cancer history and cognitive outcomes, suggesting that lifestyle and health factors play a role in the relationship.
Key unanswered questions remain: Does frequent medical follow-up in cancer survivors lead to earlier detection of cognitive decline? Are there biological mechanisms linking cancer history and dementia progression? How do social determinants of health, including socioeconomic status and access to care, contribute to the observed differences across racial and ethnic groups? Future research with larger, geographically diverse samples and more detailed clinical information on cancer and dementia subtypes is needed to explore these possibilities.
About this cancer and dementia research news
Author: Press Office
Source: University of Alabama at Birmingham
Contact: Press Office – University of Alabama at Birmingham
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Original Research: Closed access.
“The Relationship Between Prior Cancer Diagnosis and All-Cause Dementia Progression Among US Adults” by E. Fowler et al. Journal of Alzheimer’s Disease
Abstract
The Relationship Between Prior Cancer Diagnosis and All-Cause Dementia Progression Among US Adults
Background: Cancer-related cognitive impairment (CRCI), a common consequence of cancer and its treatments, produces cognitive symptoms that overlap with dementia syndromes. Cross-sectional studies have reported an inverse relationship between cancer and dementia, but longitudinal evidence on how prior cancer affects dementia progression has been limited.
Objective: To assess the association between a history of cancer and longitudinal progression of dementia.
Methods: Electronic health record data from July 2003 to February 2020 were extracted from a single academic medical center. Dementia diagnoses and prior cancer history were identified using ICD-9/10 codes. Cognitive decline was measured with the Alabama Brief Cognitive Screener (ABCs). Adjusted linear mixed models estimated baseline cognition and rate of progression by cancer history, including stratified analyses by race and ethnicity.
Results: The study included 3,809 participants with dementia, of whom 672 (17.6%) had a prior cancer diagnosis. Those with cancer history showed higher baseline cognition (β: 1.07, 95% CI: 0.45, 1.69) and a similar rate of decline compared with those without cancer history. Non-Hispanic Black participants had lower cognitive scores at baseline and across follow-up regardless of cancer history, compared with non-Hispanic White participants and other race/ethnicity groups.
Conclusion: In this longitudinal retrospective study, individuals with a prior cancer diagnosis had better cognitive function at the time of dementia diagnosis and no faster cognitive decline than those without prior cancer. The association was attenuated by smoking and comorbidities, and racial disparities persisted, with non-Hispanic Black participants showing worse cognitive outcomes regardless of cancer history. Further research should examine the roles of smoking, comorbid conditions, cancer and dementia subtypes, and social determinants of health in shaping cognitive trajectories.