White matter and neurochemical mechanisms underlying age-related differences in motor processing speed

Amirhossein Rasooli; Hamed Zivari Adab; Peter Van Ruitenbeek; Akila Weerasekera; Sima Chalavi; Koen Cuypers; Oron Levin; Thijs Dhollander; Ronald Peeters; Stefan Sunaert; Dante Mantini; Stephan P Swinnen

doi:10.1016/j.isci.2023.106794

White matter and neurochemical mechanisms underlying age-related differences in motor processing speed

iScience. 2023 May 3;26(6):106794. doi: 10.1016/j.isci.2023.106794. eCollection 2023 Jun 16.

Authors

Amirhossein Rasooli^{1

2}, Hamed Zivari Adab^{1

2}, Peter Van Ruitenbeek^{1

3}, Akila Weerasekera^{1

2

4}, Sima Chalavi^{1

2}, Koen Cuypers^{1

2

5}, Oron Levin^{1

2}, Thijs Dhollander⁶, Ronald Peeters⁷, Stefan Sunaert⁷, Dante Mantini^{1

2}, Stephan P Swinnen^{1

2}

Affiliations

¹ Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
² KU Leuven Brain Institute, KU Leuven, Leuven, Belgium.
³ Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD Maastricht, the Netherlands.
⁴ Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
⁵ REVAL Rehabilitation Research Center, Hasselt University, Diepenbeek, Belgium.
⁶ Murdoch Children's Research Institute, Melbourne, VIC, Australia.
⁷ KU Leuven, Department of Imaging and Pathology, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.

Abstract

Aging is associated with changes in the central nervous system and leads to reduced life quality. Here, we investigated the age-related differences in the CNS underlying motor performance deficits using magnetic resonance spectroscopy and diffusion MRI. MRS measured N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr) concentrations in the sensorimotor and occipital cortex, whereas dMRI quantified apparent fiber density (FD) in the same voxels to evaluate white matter microstructural organization. We found that aging was associated with increased reaction time and reduced FD and NAA concentration in the sensorimotor voxel. Both FD and NAA mediated the association between age and reaction time. The NAA concentration was found to mediate the association between age and FD in the sensorimotor voxel. We propose that the age-related decrease in NAA concentration may result in reduced axonal fiber density in the sensorimotor cortex which may ultimately account for the response slowness of older participants.

Keywords: Cognitive neuroscience; Neuroscience; Physics magnetic resonance imaging.