To provide an excellent preventive or therapeutic agent for dementia and schizophrenia based on serotonin 5-HT5A receptor modulating action. A tetrahydroisoquinoline derivative characterized by a structure in which an acylguanidino group is bonded to an N atom such as a tetrahydroisoquinoline ring and a ring group is bonded to an unsaturated ring has a potent 5-HT5A receptor modulating action, Based on this finding, the present invention was found to have an excellent pharmacological action, and was found to be useful as a preventive or therapeutic agent for dementia, schizophrenia, etc., and the present invention was completed. [Selection figure] None【課題】セロトニン5-HT5A受容体調節作用に基づく、認知症及び統合失調症の、優れた予防または治療剤を提供すること。【解決手段】テトラヒドロイソキノリン環等のN原子にアシルグアニジノ基が結合し、不飽和の環に環基が結合した構造を特徴とするテトラヒドロイソキノリン誘導体が、強力な5-HT5A受容体調節作用と、これに基づく優れた薬理作用を有することを見い出し、認知症、統合失調症等の予防又は治療剤として有用であることを知見して、本発明を完成した。【選択図】なし
