Chronic kidney disease is associated with incident cognitive impairment in the elderly: The INVADE study

Background. Limited data exist regarding the relationship between decreased renal function and cognitive impairment.Methods. A total of 3679 participants of the Intervention Project on Cerebrovascular Diseases and Dementia in the Community of Ebersberg (INVADE) composed the community-based cohort study. Measures of renal function were estimated using the Cockcroft-Gault equation and divided into normal, mild and moderate-to-severe impaired renal function (creatinine clearance ≥60, 45-59 and <45 mLmin1.73 m ², respectively). The main outcome measures were cognitive impairment at baseline and new cognitive impairment after a 2-year follow-up. Cognitive function was measured using the 6-Item Cognitive Impairment Test (6CIT). Multiple logistic regression analysis was used to assess the association between renal function and cognitive impairment.Results. At baseline, 396 participants (10.8) had cognitive impairment. After the 2-year follow-up, 194 participants (6.2) developed new cognitive impairment. The incidence of cognitive impairment across the groups with normal renal function, mild and moderate-to-severe kidney disease at baseline were 5.8, 9.9 and 21.5, respectively. Multiple logistic regression analysis after adjustment for possible confounders including traditional cardiovascular risk factors showed a significant association for participants with moderate-to-severe kidney disease at baseline to develop new cognitive impairment after the 2-year follow-up odds ratio: 2.14 (95 confidence interval: 1.18-3.87), P = 0.01.Conclusions. In summary, moderate-to-severe impaired renal function is associated with incident cognitive impairment after 2 years in a large cohort of elderly subjects.