A number of the genes identified in this work are also identified in genome wide association and/or candidate gene datasets for heritable disorders or phenotypes that co-occur with addictions [25]. Differences in memory and cognitive systems have long been identified in addicted individuals; we have identified significant overlaps between the addiction associated genes listed below and the results of GWA studies for individual differences in cognitive abilities. NRXN3 and a number of other genes listed in Table 2 also display associations with the memory-associated neurodegenerative disorder, Alzheimer's disease (Hishimoto et al, submitted). Frontal lobe volumes are smaller in several studies of substance dependent individuals or their offspring; there is significant overlap between GWA results for frontal lobe volumes and addiction [25]. Overall GWA results for bipolar disorder, in which a majority of individuals may abuse or be dependent on addictive substances, overlap with addiction GWA data [25]. There is also a significant overall overlap between addiction vulnerability GWA data and the genes identified in studies of success in smoking cessation [25].
