Processing speed and the relationship between Trail Making Test-B performance, cortical thinning and white matter microstructure in older adults

Sarah E MacPherson; Simon R Cox; David A Dickie; Sherif Karama; John M Starr; Alan C Evans; Mark E Bastin; Joanna M Wardlaw; Ian J Deary

doi:10.1016/j.cortex.2017.07.021

Processing speed and the relationship between Trail Making Test-B performance, cortical thinning and white matter microstructure in older adults

Cortex. 2017 Oct:95:92-103. doi: 10.1016/j.cortex.2017.07.021. Epub 2017 Aug 9.

Authors

Sarah E MacPherson¹, Simon R Cox², David A Dickie³, Sherif Karama⁴, John M Starr⁵, Alan C Evans⁶, Mark E Bastin⁷, Joanna M Wardlaw⁷, Ian J Deary⁸

Affiliations

¹ Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK; Department of Psychology, University of Edinburgh, UK. Electronic address: sarah.macpherson@ed.ac.uk.
² Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK; Department of Psychology, University of Edinburgh, UK; Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK.
³ Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK; Department of Neuroimaging Sciences, Centre for Clinical Brain Sciences, University of Edinburgh, UK.
⁴ Department of Neurology and Neurosurgery, McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Verdun, QC, Canada.
⁵ Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK; Alzheimer Scotland Dementia Research Centre, The University of Edinburgh, Edinburgh, UK.
⁶ Department of Neurology and Neurosurgery, McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
⁷ Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK; Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK; Department of Neuroimaging Sciences, Centre for Clinical Brain Sciences, University of Edinburgh, UK.
⁸ Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, UK; Department of Psychology, University of Edinburgh, UK.

Abstract

Part B of the Trail Making Test (TMT-B) is widely used as a quick and easy to administer measure of executive dysfunction. The current study investigated the relationships between TMT-B performance, brain volumes, cortical thickness and white matter water diffusion characteristics in a large sample of older participants, before and after controlling for processing speed. Four hundred and eleven healthy, community-dwelling older adults who were all born in 1936 were assessed on TMT-B, 5 tests of processing speed, and provided contemporaneous structural and diffusion MRI data. Significant relationships were found between slower TMT-B completion times and thinner cortex in the frontal, temporal and inferior parietal regions as well as the Sylvian fissure/insula. Slower TMT-B completion time was also significantly associated with poorer white matter microstructure of the left anterior thalamic radiation, and the right uncinate fasciculus. The majority of these associations were markedly attenuated when additionally controlling for processing speed. These data suggest that individual differences in processing speed contribute to the associations between TMT-B completion time and the grey and white matter structure of older adults.

Keywords: Aging; Executive function; Neuroimaging; Processing speed; Trail Making Test.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Aging / psychology*
Cerebral Cortex / diagnostic imaging*
Diffusion Magnetic Resonance Imaging
Executive Function / physiology*
Female
Humans
Male
Reaction Time / physiology*
Trail Making Test
White Matter / diagnostic imaging*

Abstract

Publication types

MeSH terms

Grants and funding