A HN derivative, colivelin was generated as a hybrid peptide containing activity-dependent neurotrophic factor (ADNF) C-terminally fused to a shorter 17-amino acid form, AGA-(C8R)HNG17 which was able to restore cognitive function in both an AD mouse model, and in AD patients involving JAK2/STAT3 signalling (Chiba et al., 2005; Arisaka et al., 2008). Here, JAK2 is linked to Alzheimer disease.