Greater than the sum of its parts: δ can be constructed from item level data

Donald R Royall, Ray Palmer, Teruyuki Matsuoka, Yuka Kato, Shogo Taniguchi, Mayu Ogawa, Hiroshi Fujimoto, Aiko Okamura, Keisuke Shibata, Kaeko Nakamura, Shutaro Nakaaki, Hiroyuki Koumi, Masaru Mimura, Kenji Fukui, Jin Narumoto

Research output: Contribution to journalArticle

8 Scopus citations


"δ", a latent variable constructed from cognitive performance and functional status measures, can accurately diagnose dementia. The minimal assessment needed is unknown. We have constructed a δ homolog, "dTexas", from Telephone Executive Assessment Scale (Texas) items, and validated it in a convenience sample of Japanese persons (n=176). dTexas scores correlated strongly with both Instrumental Activities of Daily Living (IADL) (r=-0.86, p<0.001) and Clinical Dementia Rating Scale (CDR) (r=0.71, p<0.001). Constructed independently of their diagnoses, dTexas scores accurately distinguished dementia versus controls (area under the receiver operating curve [(AUC; ROC)=0.92], dementia versus mild cognitive impairment (MCI) (AUC=0.80) and controls versus MCI (AUC=0.74). These AUCs are higher than those of multiple observed executive measures, as reported recently by Matsuoka et al., 2014. A dTexas score of -0.58 best discriminated between dementia versus controls with 90.1 sensitivity and 80.0 specificity.

Original languageEnglish (US)
Pages (from-to)571-579
Number of pages9
JournalJournal of Alzheimer's Disease
Issue number2
Publication statusPublished - Oct 9 2015



  • CLOX
  • dementia
  • executive function
  • EXIT25
  • Instrumental Activities of Daily Living

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Geriatrics and Gerontology
  • Clinical Psychology

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