Camsari, Gamze Balci

Background: Dementia, vascular disease, and cancer increase with age, enabling complex comorbid interactions. Understanding vascular and cancer contributions to dementia risk and neuropathology in oldest-old may improve risk modification and outcomes. Objective: Investigate the contributions of vascular factors and cancer to dementia and neuropathology. Methods: Longitudinal clinicopathologic study of prospectively followed Mayo Clinic participants dying≥95 years-old who underwent autopsy. Participants were stratified by dementia status and compared according to demographics, vascular risk factors, cancer, and neuropathology. Results: Participants (n = 161; 83% female; 99% non-Hispanic whites)≥95 years (95–106 years-old) with/without dementia did not differ based on demographics. APOE ɛ2 frequency was higher in no dementia (20/72 [28%]) versus dementia (11/88 [12%]; p = 0.03), but APOE ɛ4 frequency did not differ. Coronary artery disease was more frequent in no dementia (31/72 [43%]) versus dementia (23/89 [26%]; p = 0.03) associated with 56% lower dementia odds (odds ratio [OR] = 0.44 [confidence interval (CI) = 0.19–0.98]; p = 0.04) and fewer neuritic/diffuse plaques. Diabetes had an 8-fold increase in dementia odds (OR = 8.42 [CI = 1.39–163]; p = 0.02). Diabetes associated with higher cerebrovascular disease (Dickson score; p = 0.05). Cancer associated with 63% lower dementia odds (OR = 0.37 [CI = 0.17–0.78]; p < 0.01) and lower Braak stage (p = 0.01). Conclusion: Cancer exposure in the oldest-old was associated with lower odds of dementia and tangle pathology, whereas history of coronary artery disease was associated with lower odds of dementia and amyloid-β plaque pathology. History of diabetes mellitus was associated with increased odds of dementia and cerebrovascular disease pathology. Cancer-related mechanisms and vascular risk factor reduction strategies may alter dementia risk and neuropathology in oldest-old.

AbstractBackgroundAdvancing age is an important risk factor for dementia and cancer. An inverse association between these conditions has been described, yet caution from potential biases/confounders is warranted. Dementia and cancer may represent a spectrum of opposing dysregulated degenerative (apoptosis) and growth (proliferative) pathways respectively (Driver, 2014). Risk or resiliency factors affecting these pathways may influence cognitive outcomes in the oldest‐old. We sought to investigate demographics, clinical characteristics, and the impact of medical comorbidity on possible risk‐resiliency factors for neurodegeneration in nondemented and demented oldest‐old who died and underwent autopsy.MethodMedical records of 161 decedents (female n=134) from the Mayo Clinic 95+ year‐old cohort (age range 95‐106 years‐old) were reviewed. Groups consisting of nondemented (n=72) and demented (n=89) decedents were stratified and compared according to demographics and clinical variables, including history of cancer. Autopsy and neuropathologic evaluation was also conducted.ResultAge at death, sex, race, and education showed no differences between nondemented and demented decedents. History of cancer was higher in nondemented (57%) compared to demented decedents (30%) (p=0.002). APOE ε4 allele presence did not differ amongst groups, while APOE ε2 allele was more common in the nondemented group (p=0.026). History of coronary artery disease was higher in the nondemented (p=0.033). No differences were observed in other vascular risk factors, alcohol use, or depression. Smoking history approached significance and was higher in nondemented compared to demented (p=0.068). MMSE scores were higher in the nondemented group (p<0.001). Neuropathology findings included a lower Braak tangle staging in nondemented (median=III) compared to demented (median=V) groups (p<0.001) and less frequent diffuse plaques observed in the nondemented (67%) compared with those demented (93%) (p<0.001).ConclusionDementia is less frequent among cancer survivors in the 95+ oldest‐old. Disease‐related mechanisms associated with malignancy and surviving it may be protective against neurodegeneration in the oldest old.