Dear Doug, Thank you for your instantaneous response! Correcting for disease burden was actually a reviewer comment. We calculated mean cortical thickness estimates for regions that showed vertex-wise age-related cortical thickness differences between groups (using qdec) and then graphed out the slope aging-patterns between normal controls and patients, by extracting the data into SPSS. Basically, our findings indicated that for selected regions, the patients showed a steeper age-related decline. It was suggested by the reviewer to correct the correlation between age and cortical thickness for disease burden in the patient group (using partial correlations in SPSS). Would this be an alternative way? It would sure safe us from re-running our data:) Very Best Regards, Catherine