Researchers from China Pharmaceutical University and Jiangsu Nhwa Pharmaceutical Co. Ltd. have synthesized azetidine-containing compounds acting as muscarinic M4 receptor positive allosteric modulators (PAMs) reported to be useful for the treatment of Alzheimer’s disease, asthma, pain, schizophrenia, pulmonary hypertension, Huntington’s disease, Parkinson’s disease and sleep disorders among others.