Participants trained using a program called “Yawaraka Atama Juku (flexible thinking club)” developed by Nintendo Co., Ltd., using a portable game console (Nintendo DS LL, Kyoto, Japan) and performed drills consisting of easy calculations (Kawashima, 2003), mazes, and mistake-searching in pictures. Each session was 40 min long and were conducted once per week over the 6-months intervention period (total sessions: 24). Each session was moderated by nurses, certified care workers, or psychiatric social workers employed at the respective nursing facility.