7, p = 0.01), and, in particular, increases in left-sided CA1 subfield CBV (t23 = 3.5, p = 0.002). To test for longitudinal changes Dactolisib in CBV from baseline to follow-up, a repeated-measures analysis with

time (baseline and follow-up) and subregion (EC, DG, CA3, CA1, and SUB) as within-subjects factors and progression status (psychosis versus not) as a between-subjects factor was used. The multivariate component of the analysis identified a significant subregion by time by group interaction (F4, 13 = 3.5, p = 0.04). Post hoc t tests revealed this interaction to be driven by CBV increases in subiculum from baseline to follow-up bilaterally in the progressor group (t18 = 3.7, p = 0.002); increases in CA1 CBV did not change significantly from time 1 to time 2, remaining relatively higher in the progressor group at both baseline (t23 = 2.7, p = 0.01) and follow-up (t18 = 3.1, p = 0.006). EC, DG, and CA3 were not significantly different between groups at MAPK inhibitor baseline or follow-up. Antipsychotic or antidepressant drug exposure had no effect on CBV values in this analysis (Figure 1A). To confirm that hippocampal hypermetabolism is predictive

of psychosis, we entered hippocampal left anterior CA1 CBV into a Cox regression model, controlling for demographics and follow-up interval, with time to psychosis as the dependent variable. Left anterior CA1 CBV powerfully predicted time to psychosis in the Cox model (Wald (t1) = 8.5, p = 0.003). We further explored whether brain metabolism or symptoms were more powerful predictors of outcome. Similar to other larger prodromal cohort studies (Cannon et al., 2008), unusual thought content (Wald(t1) = 2.9, p = 0.09) suspiciousness, (Wald(t1) = 2.9, Sodium butyrate p = 0.08) and conceptual disorganization (Wald(t1) =

3.5, p = 0.06) also predicted time to psychosis at a trend level when entered separately into this model. When behavioral variables were entered together into the model with left anterior CA1 CBV, brain metabolism maintained its predictive strength (Wald(t1) = 8.8, p = 0.003), whereas behavioral measures were no longer predictive of clinical outcome (all p’s > 0.33), suggesting that left CA1 CBV is a more sensitive predictor of clinical outcome to first episode psychosis than subthreshold psychotic symptoms. In the same subjects, MRI was used to map hippocampal structure and generate measures of hippocampal volume and hippocampal shape as previously described (Schobel et al., 2009a; Styner et al., 2003, 2007). At the initial assessment, to test for baseline differences in hippocampal volume, a repeated-measures analysis of variance with side (left, right) as within-subject factors and outcome (progression to psychosis versus nonprogression) as between-subjects factor revealed no main effect of progression status (F1,22 = 0.96, p = 0.36) and no side-by-conversion interaction (F1,22 = 1.1, p = 0.30).