Associations Between Vascular Diseases and Alzheimer’s Disease or Related Dementias in a Large Cohort of Men and Women with Colorectal Cancer

BACKGROUND: Long term risk of Alzheimer’s disease (AD) and related dementias (ADRD) associated with vascular diseases in people with colorectal cancer is unknown. OBJECTIVE: To determine the risk of ADRD in association with cardiovascular diseases (CVD), stroke, hypertension, and diabetes in a cohort of patients with colorectal cancer. METHODS: This retrospective cohort study consisted of 210,809 patients diagnosed with colorectal cancer at age≥65 years in 1991–2015 from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database with follow-up from 1991–2016, who were free of any ADRD at the baseline (<12 months prior to or < 30 days after the date of cancer diagnosis). RESULTS: The crude 26-year cumulative incidence of total ADRD in men and women with colorectal cancer was higher in those with versus without CVD (31.92% versus 28.12%), with versus without stroke (39.82% versus 26.39%), with versus without hypertension (31.88% versus 24.88%), and with versus without diabetes (32.01% versus 27.66%). After adjusting for socio-demographic and tumor factors, the risk of developing ADRD was significantly higher in patients with CVD (adjusted hazard ratio: 1.17, 95% confidence intervals: 1.14–1.20), stroke (1.65, 1.62–1.68), hypertension (1.07, 1.05–1.09), and diabetes (1.26, 1.24–1.29) versus persons without. For those with 1, 2, 3 and 4 vascular diseases present versus absent, the risk of AD increased from 1.12 (1.07–1.16) to 1.31 (1.25–1.36), 1.66 (1.57–1.75), and 2.03 (1.82–2.27). CONCLUSION: In older patients with colorectal cancer, a significant dose-response relationship was observed between an increasing number of these vascular diseases and the risk of all types of dementia.