Are neurocognitive speed and inconsistency similarly affected in type 2 diabetes?

Abstract

Type 2 diabetes (T2D) is a disease of aging with indirect but detectable and cumulative neurological implications. We systematically tested whether neurocognitive speed (mean rate) or inconsistency (intraindividual variability) was the more sensitive clinical marker of T2D. Three of four research questions used a cross-sectional wave of the Victoria Longitudinal Study (VLS) divided into T2D (age 55–81 years) and control (age = 53–91 years) groups. The fourth question addressed relative two-wave longitudinal changes. Each of four speeded tasks produced intraindividual mean rate (IM) and intraindividual standard deviation (ISD) scores. First, the T2D group performed more slowly than the controls. Second, this deficit extended to inconsistency, but less uniformly. Third, based on logistic regression analyses, IM was the more effective predictor of T2D status. Fourth, we observed similar longitudinal change patterns for IM and ISD. Results are linked to the theoretical location of T2D on an adjusted neural vulnerability continuum.

Keywords:

• Aging
• Intraindividual variability
• Logistic regression analyses
• Neurocognitive speed
• Type 2 diabetes
• Victoria Longitudinal Study

Acknowledgments

This research was supported by a grant from the U.S. National Institutes of Health (National Institute on Aging) to Roger A. Dixon (R37 AG008235), who is also supported by the Canada Research Chairs program. We appreciate the many important contributions of Victoria Longitudinal Study (VLS) participants and staff (notably Ashley Fischer, Jill Friesen, and Terry Perkins) to the present research. Further information about the VLS may be accessed via: http://www.ualberta.ca/~vlslab/index.html