Various subtypes of SSTRs are distributed differently across the central nervous system and the peripheral nervous system23. Gray shades indicate the existence of the receptor subtypes in the corresponding area. Red shades indicate receptor subtypes with a strong binding affinity (IC50 < 10 nM). Note that SST shows a high binding affinity for all SSTR subtypes. CST resembles SST and has a similar strong binding affinity for all SSTR subtypes. SST analogs have selective binding properties for certain subtypes of SSTRs and sometimes have higher affinity for SSTRs than SST. Alterations in SSTR expression levels are observed in the neurological disorders discussed in this paper. It is well known that the expression levels of SSTRs are altered in AD patients42, whereas the SSTR expression level in other disorders is less clear.