Decision making ability has been reported to be impaired in schizophrenia patients, but no research has examined the genetic bases of this impairment. This study investigated how decision making was affected by the genetic variants in the serotonin transporter gene (triallelic 5- HTTLPR) and serotonin receptor 1A gene (rs6295) and their interaction in 465 schizophrenia patients and 448 healthy controls. The Iowa Gambling Task (IGT) was used to evaluate decision making under ambiguity (the first 40 trials) and decision making under risk (the last 60 trials). Results showed that, among the patients, the main effects of 5- HTTLPR (F(2) (,16) = 6.54, P = 0.002) and HTR1A rs6295 (F(2) (,16) = 3.87, P = 0.021) polymorphisms and their interaction effect (F(4) (,16) = 3.32, P = 0.005) were significant for the first 40 trials, with the GG genotype of HTR1A rs6295, the L'L' genotype of 5- HTTLPR and the GG-L'L' combination showing poorer IGT performance than their counterparts. Results for the healthy controls showed a similar pattern but did not reach statistical significance. No significant effects were found for the last 60 trials. These results are discussed in terms of their implications for our understanding of the genetic mechanisms of decision making in schizophrenia patients as well as healthy adults.

BACKGROUND: We previously reported that infants who developed autism spectrum disorder (ASD) had increased cerebrospinal fluid (CSF) in the subarachnoid space (i.e., extra-axial CSF) from 6 to 24 months of age. We attempted to confirm and extend this finding in a larger independent sample. METHODS: A longitudinal magnetic resonance imaging study of infants at risk for ASD was carried out on 343 infants, who underwent neuroimaging at 6, 12, and 24 months. Of these infants, 221 were at high risk for ASD because of an older sibling with ASD, and 122 were at low risk with no family history of ASD. A total of 47 infants were diagnosed with ASD at 24 months and were compared with 174 high-risk and 122 low-risk infants without ASD. RESULTS: Infants who developed ASD had significantly greater extra-axial CSF volume at 6 months compared with both comparison groups without ASD (18% greater than high-risk infants without ASD; Cohens d = 0.54). Extra-axial CSF volume remained elevated through 24 months (d = 0.46). Infants with more severe autism symptoms had an even greater volume of extra-axial CSF from 6 to 24 months (24% greater at 6 months, d = 0.70; 15% greater at 24 months, d = 0.70). Extra-axial CSF volume at 6 months predicted which high-risk infants would be diagnosed with ASD at 24 months with an overall accuracy of 69% and corresponding 66% sensitivity and 68% specificity, which was fully cross-validated in a separate sample. CONCLUSIONS: This study confirms and extends previous findings that increased extra-axial CSF is detectable at 6 months in high-risk infants who develop ASD. Future studies will address whether this anomaly is a contributing factor to the etiology of ASD or an early risk marker for ASD.