The present invention provides a novel therapeutic agent or prophylactic agent for dementia. The present invention provides a therapeutic agent, prophylactic agent, or the like for dementia that contains a substance such as the following as an active ingredient: antibodies that specifically exhibit an antigen-antibody reaction to tau proteins of which the area around Ser413 of SEQ ID NO: 1 is phosphorylated； and peptides of which the area around Ser413 is phosphorylated.本發明係提供一種新穎的失智症治療劑或預防劑。本發明係提供一種含有對於序列編號1之Ser413周邊經磷酸化的Tau蛋白質產生特異性抗原抗體反應之抗體、或Ser413周邊經磷酸化之胜肽作為有效成分的失智症治療劑或預防劑等。
