Compromised white matter integrity in obesity

Abstract

Obesity is associated with both structural and functional changes of the central nervous system. While gray matter alterations in obesity point to a consistent reduction with increasing body mass index (BMI), volumetric changes in white matter are more complex and less conclusive. Hence, more recently, diffusion tensor imaging (DTI) has been employed as a highly sensitive tool to investigate microstructural changes in white matter structure. Parameters of diffusivity and anisotropy are used to evaluate white matter and fibre integrity as well as axonal and myelin degeneration. Fractional anisotropy (FA) is the most commonly used parameter as it is the best estimate of fibre integrity. The focus of this review was on the relationship between obesity and brain alterations assessed by DTI. Altogether, these studies have shown a loss of white matter integrity with obesity-related factors, especially in tracts within the limbic system and those connecting the temporal and frontal lobe. More specifically, multiple studies found an inverse association between BMI and FA in the corpus callosum, fornix, cingulum and corona radiata in elderly and young adults as well as children. Furthermore, significant interactions were observed between BMI and age, pointing to accelerated ageing of white matter structure in obese.

Obesity associated with increased brain age from midlife

“…These in turn have been linked to white-matter changes (Bolzenius et al., 2013, Kullmann et al., 2015). This biological mechanism suggests that the initial insult of obesity may lead to self-perpetuating damage, which is manifested as structural changes akin to those seen in normal aging.…”

Hallmarks of Brain Aging: Adaptive and Pathological Modification by Metabolic States

“…On average, the cognitive performance of individuals who are metabolically morbid is poorer than their age-matched healthy counterparts (Kullmann et al, 2016; Stillman et al, 2017). Brain imaging studies have documented reduced gray matter volumes and white matter integrity in multiple brain regions, and reduced functional connectivity between brain regions in obese individuals, particularly those with abdominal obesity and insulin resistance (Debette et al, 2014; Janowitz et al, 2015; Kullmann et al, 2015). Generally similar abnormalities in brain structure and neuronal network connectivity occur in individuals with type 2 diabetes (Macpherson et al, 2017).…”

Interplay between exercise and dietary fat modulates myelinogenesis in the central nervous system

“…The loss of myelin is also a recognized part of normal ageing and a risk factor in obesity contributing to cognitive and sensorimotor decline (Kullmann et al 2015). The physiological significance of oligodendrocytes relates not only to the ability of the myelin sheath to electrically insulate axons thereby increasing the capacity for information processing, but also to their ability to support axon metabolism (Funfschilling et al 2012; Hirrlinger and Nave 2014).…”