The HBCS cohort is composed of 8760 individuals born between the years 1934 and 1944 in Helsinki University Central Hospital. Between 2001 and 2003, a randomly selected sample of 928 males and 1075 females participated in a clinical study with a focus on cardiovascular, metabolic and reproductive health, cognitive function and depressive symptoms. For the sub-study on cognitive performance we invited those subjects from the original sample, who were still living in the greater Helsinki area (n = 1586). The 1279 subjects who attended were administered a test of cognitive performance in the years 2004–2006. After exclusion of subjects with a history of stroke (n = 29), type 1 diabetes (n = 1) and invalid test results (n = 3), the sample with valid phenotype and genotype data available for analyses consisted of 1080 men (n = 472) and women (n = 608). The mean age of the subjects at time of assessment was 63.9 (SD = 2.8) years. The mean age of the men was 63.6 (SD = 2.6) and of the women was 64.1 (SD = 3.0) years.
