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

Donald R. Royall, Raymond F. 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 Citations (Scopus)


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



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

ASJC Scopus subject areas

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

Cite this

Royall, D. R., Palmer, R. F., Matsuoka, T., Kato, Y., Taniguchi, S., Ogawa, M., Fujimoto, H., Okamura, A., Shibata, K., Nakamura, K., Nakaaki, S., Koumi, H., Mimura, M., Fukui, K., & Narumoto, J. (2015). Greater than the sum of its parts: δ can be constructed from item level data. Journal of Alzheimer's Disease, 49(2), 571-579.