MILD COGNITIVE IMPAIRMENT IS, IN CONTRAST TO DEMENTIA, ASSOCIATED WITH AN INCREASED RISK OF CANCER

Abstract

Dementia and cancer are major public health concerns. Previous studies showed an inverse relation between dementia and cancer. However, it is uncertain whether this observation is based on biological mechanisms or if it is due to epidemiological limitations. Mild cognitive impairment (MCI) represents the earliest clinical features of dementia. We investigated the relation between MCI and cancer in addition to the association between dementia and cancer to better understand the nature of this finding. We assessed the relation between incident dementia and cancer in 13,207 participants of the prospective population-based Rotterdam Study. The association between MCI and cancer was studied in 5,181 persons of this cohort. Only solid and hematological cancer types were included. Cox proportional hazard models were used, adjusting for important confounding factors including age, sex, body mass index, education level, smoking status, and alcohol use. In addition, we excluded the first two and five years of follow-up time to limit the effect of reversed causality. In total 1,404 patients were diagnosed with dementia of whom 63 developed cancer. Dementia was associated with a decreased risk of cancer (hazard ratio (HR) 0·53; 95% CI 0·41–0·68). Seventy seven out of 501 persons with MCI were diagnosed with cancer. Persons with MCI had an increased risk of cancer (HR 1·21; 95% CI 0·95–1·53). The risk of cancer was increased after exclusion of the first two and five years of follow-up time (HR 1·28; 95% CI 0·97–1·68 and HR 1·75; 95% CI 1·21–2·53). The risk of cancer in persons with MCI was significantly higher compared to the risk in dementia patients (P <0.001).