GRM5 and Alzheimer disease: Furthermore, the mGluR5‐silent allosteric modulator (SAM) Bristol‐Myers Squibb‐984923 (BMS‐984923)6‐(fluoro‐18F)‐3‐(1H‐pyrrolo[2,3‐c]pyridin‐1‐yl)isoquinolin‐5‐amine can completely restore synaptic density in aged mouse models of AD, and the therapeutic benefit persists even after drug washout.