COGA administered a variety of neuropsychological tests to its subjects including the three used here: Wechsler Adult Intelligence Scale-Revised (WAIS-R) Block Design, WAIS Digit Symbol, and WAIS Information. In total there were 1247 European-Americans with these neuropsychological phenotypes. However, the overlap between this number and those with family GWAS data was 492. Therefore, our analyses were performed on 492 subjects. In WAIS Block Design, the subject replicates models or pictures of two-color designs with blocks. In WAIS Information, the subject answers a series of questions about factual information. In WAIS Digit Symbol, the subject writes down as quickly as possible the symbols that correspond to a series of numbers.
