The speed measures were inter-correlated, and in the Brisbane sample have been shown to be genetically related (Luciano et al., 2004), we therefore expected some overlap between these measures in the GWA results. Only one of the top hits overlapped across measures (2-choice and 8-choice RT) and this SNP was not located near any known gene. Importantly, most of the top hits for each measure showed nominally significant associations with other speed measures. The top hits for digit symbol, symbol search and 4-choice RT were all nominally significant with other speed measures; and one of the top hits for inspection time, simple RT, and all choice RT conditions each showed nominal association with four other speed measures. It is interesting to note that for symbol search, which was only measured in the LBC1936, there were associations with variables that were unmeasured in this cohort (i.e., 2-choice and 8-choice RT) suggesting that not all the common associations can be attributed to correlated type 1 error. The speed factor was most frequently nominally associated with the top hits from other variables and
