PROBLEM TO BE SOLVED: To provide a therapeutic agent effective against cognitive dysfunction occurring with Parkinson disease, and a screening method therefor.SOLUTION: The present invention provides a therapeutic agent effective against cognitive dysfunction occurring with Parkinson disease, the therapeutic agent comprising a phosphodiesterase inhibitor, an adenylate cyclase activator, or a cAMP derivative as an active ingredient.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2017,JPO&INPIT【課題】パーキンソン病に併発した認知障害に対して有用な治療剤及びそのスクリーニング方法を提供する。【解決手段】パーキンソン病に併発した認知障害の治療剤は、ホスホジエステラーゼ阻害薬、アデニル酸シクラーゼ活性化薬又はcAMP誘導体を有効成分とする。【選択図】図3