Associations between reaction time measures and white matter hyperintensities in very old age

Becky I Haynes,David Bunce,Nicole A Kochan,Wei Wen,Henry Brodaty,Perminder S Sachdev

doi:10.1016/j.neuropsychologia.2017.01.021

Becky I Haynes, David Bunce + Show 4 more

Open Access

https://doi.org/10.1016/j.neuropsychologia.2017.01.021

Copy DOI

Abstract

In old age, a relationship has been reported between intraindividual variability (IIV) in reaction time and white matter integrity as evidenced by white matter hyperintensities (WMH). However, it is unclear how far such associations are due to incipient neurodegenerative pathology in the samples investigated. The present study examined the relationship between IIV and WMH in older individuals (N=526) drawn from the Sydney Memory and Ageing Study. Using a complex reaction time (RT) task, greater IIV and mean-RT were related to a higher WMH burden in the frontal lobe. Critically, significant associations remained having taken future dementia into account suggesting that they were not explained by incipient dementia. Additionally, independent measures of executive function accounted for the association between RT metrics and WHM. The results are consistent with the view that frontally-supported cognitive processes are involved in IIV-WMH relations, and that RT measures are sensitive to compromise in white matter structures in non-demented older individuals.

Highlights

Intraindividual variability (IIV), or inconsistency (e.g., Hultsch, MacDonald, & Dixon, 2002), refers to within-person variation in cognitive performance over time, and is often measured by the trial-by-trial variation in reaction times (RT) for a given cognitive task
Years in education was negatively associated with mean-RT, while sex was related to SRT mean-RT and frontal white matter hyperintensities (WMH)
SRT intraindividual standard deviations (ISD) was not associated with WMH in any region, entering frontal WMH increased the shared variance in CRT ISD explained by the model (ΔR2=.012, F(2,520)=3.25, p=.040)

Summary

Introduction

Intraindividual variability (IIV), or inconsistency (e.g., Hultsch, MacDonald, & Dixon, 2002), refers to within-person variation in cognitive performance over time, and is often measured by the trial-by-trial variation in reaction times (RT) for a given cognitive task. Associations have been shown between IIV and white matter hyperintensities (WMH: Bunce et al, 2010; Bunce et al, 2007), white matter volume (Jackson, Balota, Duchek, & Head, 2012; Lovden et al, 2013; Ullen, Forsman, Blom, Karabanov, & Madison, 2008; Walhovd & Fjell, 2007) and diffusion tensor imaging metrics (e.g., FA - fractional anisotropy) (Deary et al, 2006; Fjell, Westlye, Amlien, & Walhovd, 2011; Mella, de Ribaupierre, Eagleson, & de Ribaupierre, 2013; Moy et al, 2011). Neuropathological studies suggest that IIV is elevated in persons with frontal lobe damage (Murtha, Cismaru, Waechter, & Chertkow, 2002; Stuss et al, 2003) while in healthy populations, associations have been identified between increased IIV and frontal WMH (Bunce et al, 2010; Bunce et al, 2007) and pre-frontal white matter volume (Jackson et al, 2012; Lovden et al, 2013)

Methods

Results

Conclusion