δ Scores are Exportable Across Cultural and Linguistic Boundaries

Article type: Research Article

Authors: Royall, Donald R.^{a; b; c; d; *} | Palmer, Raymond F.^c | Matsuoka, Teruyuki^e | Kato, Yuka^e | Taniguchi, Shogo^f | Ogawa, Mayu^e | Fujimoto, Hiroshi^e | Okamura, Aiko^g | Shibata, Keisuke^h | Nakamura, Kaeko^e | Nakaaki, Shutaroⁱ | Koumi, Hiroyuki^j | Mimura, Masaruⁱ | Fukui, Kenji^e | Narumoto, Jin^e

Affiliations: [a] Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX, USA | [b] Department of Medicine, The University of Texas Health Science Center, San Antonio, TX, USA | [c] Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, TX, USA | [d] South Texas Veterans’ Health System, Audie L. Murphy Division GRECC, San Antonio, TX, USA | [e] Department of Psychiatry, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan | [f] Reinan Hospital, Mikatakaminakagun, Wakasacho, Fukui, Japan | [g] Yashio Hospital, Yashio-shi, Saitama, Japan | [h] Kawagoe Hospital, Sakyo-ku, Kyoto, Japan | [i] Department of Neuropsychiatry, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan | [j] Department of Clinical Psychology, Faculty of Social Welfare, Hanazono University, Nishinokyo, Nakagyo-ku, Kyoto, Japan

Correspondence: [*] Correspondence to: Donald R. Royall, MD, Department of Psychiatry, the University of Texas Health Science Center, San Antonio, TX, USA. Tel.: +1 210 567 1255; E-mail: royall@uthscsa.edu

Abstract: The latent variable “δ”, can accurately diagnose dementia. Its generalizability across populations is unknown. We constructed a δ homolog (“dT2J”) in data collected by the Texas Alzheimer’s Research and Care Consortium (TARCC). From this, we calculated a composite d-score “d”. We then tested d’s generalizability across random subsets of TARCC participants and to a convenience sample of elderly Japanese persons with normal cognition (NC), mild cognitive impairment (MCI), and dementia (AD) (n = 176). dT2J was indicated by Instrumental Activities of Daily Living and psychometric measures. Embedded in this battery were the Mini-Mental Status Examination (MMSE) and an executive clock-drawing task (CLOX). Only MMSE and CLOX were available in both TARCC and the Japanese cohort. Therefore, a second composite variable, “T2J”, was constructed solely from the factor loadings of CLOX and MMSE on d. The diagnostic accuracy of T2J was estimated in the validation sample, the remainder of the TARCC cohort, and in the Japanese sample. The areas under the receiver operating curve (AUC; ROC) for T2J were compared in each sample, and against d in TARCC. The AUCs for T2J were statistically indiscriminable within TARCC, and in Japanese persons. In Japanese persons, AUCs for T2J were 0.97 for the discrimination between AD versus NC, 0.86 for AD versus MCI, and 0.79 for NC versus MCI. The AUCs for T2J in Japanese persons were higher than any individual psychometric measure in that sample. Valid d-score composites can be extracted from a subset of δ’s indicators. Moreover, those composites are exportable across cultural and linguistic boundaries.

Keywords: CLOX, dementia, δ, Instrumental Activities of Daily Living, Spearman’s g

DOI: 10.3233/JAD-150261

Journal: Journal of Alzheimer's Disease, vol. 49, no. 2, pp. 561-570, 2016