HCAR2 and Alzheimer disease: Interestingly, activation of HCAR2 by using an FDA-approved formulation of niacin (Niaspan) reduced Aβ deposition and neuronal loss, resulting in improved cognitive function in 5xFAD mice (Moutinho et al., 2022), suggesting that HCAR2 activity is required for the effective clearance of Aβ deposition during the early-onset of AD.