The present invention provides a therapeutic and/or prophylactic agent for, for example, frontal lobe dysfunction (for example, cognitive impairment (for example, cognitive impairment in Parkinson's disease, cognitive impairment caused by chronic stress, dementia with lewy bodies, progressive supranuclear palsy, frontotemporal dementia and the like) and the like), Lewy body disease (for example, cognitive impairment in Parkinson's disease, diffuse Lewy body disease, dementia with lewy bodies, movement disorder associated with Lewy body disease and the like) and the like, which contains a compound represented by the formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.本發明提供一種治療及/或預防劑，其係用於例如額葉功能障礙(例如認知損傷(例如在帕金森(Parkinson)氏病中的認知損傷、由長期壓力所引起的認知損傷、路易體(Lewy body)失智症、進行性上眼神經核麻痺症、額顳葉失智症及類似者)及類似者)、路易體病(例如在帕金森氏病中的認知損傷、彌漫性路易體病、路易體失智症、與路易體病相關聯的運動障礙及類似者)及類似者，該治療及/或預防劑含有式(I)表示的化合物或其醫藥上可接受之鹽作為活性成分。
