Figure 4.

The relative changes of the in vivo nicotinic binding sites in the brain and association with changes in the red blood cells (RBCs) AChE activity. (A) Changes from baseline in the overall ¹¹C-nicotine PET binding in the brain after 3 months of galantamine or placebo treatment (left panel) as well as after 9–12 months in all patients (right panel). **p < 0.007 compared to baseline. (B) Correlation between percent changes in the in vivo nicotinic binding sites and changes in the RBC AChE activity. The negative correlation among the Placebo group indicates that the co-dependency between the number of nicotinic binding sites and the AChE activity that was seen at baseline is still at work among the Placebo group. Note that AChE inhibition has inverse relationship with AChE activity. The galantamine treatment instead altered this basal relationship so that the nicotinic binding sites increase in accord with a reduction in (inhibition of) AChE activity by the drug. The in vivo nicotinic binding sites were assessed by PET using the ¹¹C-nicotine tracer. Here is shown percent changes in the region of interest of the “Whole brain.” All values on both axes are percentages of the individual baseline. Light squares = the Placebo group. Dark squares = the Galantamine group. PET, positron emission tomography.