Multiple regression analysis with CDR as the dependent measure, and levels of CRF-IR and SLI in the 9 cortical regions as the sets of independent variables, showed that the levels of each peptide correlated significantly with CDR (CRF-IR R2=0.49, F9,69=7.3, P=.001; SLI R2=0.37, F9,69=4.6, P<.001). Simple correlation analyses showed that the levels of CRF-IR in most regions correlated significantly (P<.05 for all, after Bonferroni correction) and negatively with CDR scores (Table 2 and Figure 5). Stepwise regression showed that the level of CRF-IR in the middle temporal gyrus (Brodmann area 21) was the best predictor of CDR (R2=0.35, F9,69=5.2, P<.001), with the level of CRF-IR in the inferior frontal gyrus (Brodmann area 44) making an additional significant contribution (R2 for CRF-IR in Brodmann area 21 plus CRF levels in Brodmann area 44=0.45; F9,69=6.8, P<.001). For SLI, the region of strongest predictive power for CDR was the occipital cortex (Brodmann area 17; R2=0.26, F9,69=3.2, P=.003). Significant correlations between CDR and the levels of SLI and CRF-IR in other regions were present (Table 2) but did not add significantly to the predictive power of CRF-IR and SLI to CDR. Identical analyses limited to the CDR 0.0 and 2.0 groups yielded a significant relationship between CDR and CRF-IR (R2=0.34; F9,54=3.0, P=.005), but not between CDR and SLI (R2=0.15; F9,54=1.1, P=.41). Stepwise regression analysis for CRF-IR showed the entorhinal cortex (Brodmann area 36/38) to be the principal region contributing to the regression results, but this regression did not reach statistical significance after correction for all possible contrasts (R2=0.19; F9,54=1.77, P=.1). Combined regression analysis of CRF-IR and SLI levels as predictors of CDR (R2=0.57) for the entire cohort showed that, when SLI was entered first, the addition of CRF-IR significantly increased the correlation from R2=0.37 to R2=0.57 (F9,60=3.0, P=.006), but when CRF-IR was entered into the regression equation first, the addition of SLI did not increase the correlation significantly from R2=0.49 to R2=0.57 (CRF-IR followed by SLI, F9,60=1.2, P=.30).