Cognitive Function

For a general measure of cognitive function, we used the Japanese version of the Mini-Mental State Examination (MMSE-J; Folstein et al., 1975; Sugishita, 2012). It consists of 30 points, with lower scores indicating impaired cognition. The Japanese version of the Executive Interview (J-EXIT25; Royall et al., 1992; Matsuoka et al., 2014) was administered to evaluate executive function. It has 25 items and includes tests for frontal lobe function, such as the aural Trail Making Test, verbal and design fluency, interference task, primitive reflex, Go/No-Go task, and Luria hand sequences. Each item is rated on a score of 0–2, and the total score ranges from 0 to 50. A higher J-EXIT25 score indicates greater impairment. The Japanese version of the Executive Clock Drawing Task (J-CLOX; Royall et al., 1998; Matsuoka et al., 2014) was also administered. The J-CLOX has two parts: J-CLOX1, an unprompted Clock Drawing Task, is considered to involve executive function; and J-CLOX2, a copying task, is considered to involve visuospatial abilities (Royall et al., 1998; Matsuoka et al., 2014). Both parts are scored on a 15-point scale, with a lower score reflecting greater impairment. The Logical Memory (LM) of the Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1987) was also applied. Short-term verbal memory was assessed using the LM I subtest of the WMS-R, while delayed verbal recall was assessed using the LM II subtest.