The protein levels of postsynaptic density 95 (PSD95), synaptophysin and neural cell adhesion molecule (NCAM) were decreased markedly in the hippocampus of the 3 × Tg-AD mice group, while the synaptic degeneration was significantly alleviated through upregulation of the synaptic protein expression in the hippocampal neurons of mice receiving DDB treatment (Figure 6A,B). Here, CHL1 is linked to Alzheimer disease.