This review outlines novel therapeutic targets for the treatment of AD, including cytokines, the JAK (Janus kinase)-STAT (signal transduction and activator of transcription) pathway, OX40-OX40L interaction, histamine H4 receptor (H4R), aryl hydrocarbon receptor (AHR), phosphodiesterase (PDE) 4, and the microbiome. The gene discussed is HRH4; the disease is Alzheimer disease.