GPR55 and Alzheimer disease: In various pre-clinical models and human investigations, the endocannabinoid system, including cannabinoid receptor type 1 (CB1) and 2 (CB2), as well as the lysophosphatidylinositol G-protein coupled receptor 55 (GPR55), endogenous cannabinoids, and enzymes that catabolize these compounds, are involved in the development of neuroinflammatory illnesses, such as AD [11].