To understand chronic kidney disease as a risk factor for dementia in different age groups, we measured glomerular filtration rate (GFR) using different biomarkers as well as albuminuria in participants of the Atherosclerosis Risk in Communities (ARIC) Study at two different time points. The participants, who were aged 54-74 years at the first and aged 70-90 years at the second time point, were then observed over several years. We demonstrated that elevated urinary albumin was similarly associated with an increased risk of dementia in both of these age groups. In addition, estimates of kidney function based on beta-2-microglobulin and cystatin-C may also be associated with dementia while more traditional estimates of kidney function based on serum creatinine were not.