Cardiorespiratory Fitness and Preserved Medial Temporal Lobe Volume in Alzheimer Disease

Abstract

Exercise and cardiorespiratory (CR) fitness may moderate age-related regional brain changes in nondemented older adults (ND). The relationship of fitness to Alzheimer's disease (AD) related brain change is understudied, particularly in the hippocampus which is disproportionately affected in early AD. The role of apolipoprotein E4 (apoE4) genotype in modulating this relationship is also unknown. Nondemented (n=56) and early-stage AD subjects (n=61) over age 65 had MRI and CR fitness assessments. Voxel-based morphometry (VBM) techniques were utilized to identify AD-related atrophy. We analyzed the relationship of CR fitness with white and gray matter within groups, assessed fitness-related brain volume change in areas most affected by AD-related atrophy, and then analyzed differential fitness-brain relationships between apoE4 carriers. Atrophy was present in the medial temporal, temporal, and parietal cortices in subjects with mild AD. There was a significant positive correlation of CR fitness with parietal and medial temporal volume in AD subjects. ND subjects did not have a significant relationship between brain volume and CR fitness in the global or SVC analyses. There was not a significant interaction for fitness × apoE4 genotype in either group. In early-stage AD, cardiorespiratory fitness is associated with regional brain volumes in the medial temporal and parietal cortices suggesting that maintaining cardiorespiratory fitness may modify ADrelated brain atrophy.

Relationships between cardiorespiratory fitness, hippocampal volume, and episodic memory in a population at risk for Alzheimer's disease

“…Honea et al. (2009) reported positive associations between right parahippocampal volume and CRF in early‐stage AD participants. A two‐year follow‐up study by this same group reported significant associations between CRF change and left parahippocampal volume in the same early‐stage AD participants (Vidoni et al., 2012).…”

“…A two‐year follow‐up study by this same group reported significant associations between CRF change and left parahippocampal volume in the same early‐stage AD participants (Vidoni et al., 2012). Interestingly, neither baseline CRF nor change in CRF was related to hippocampal volume in the cognitively healthy participants of either study (Honea et al., 2009; Vidoni et al., 2012). More recently, change in CRF following an exercise intervention has been positively associated with hippocampal head volume (Maass et al., 2015) and hippocampal tissue density (Kleemeyer et al., 2015) in cognitively healthy older adults.…”

“…For CRF, the data are equivocal with some studies reporting significant positive associations between CRF and hippocampal volume (Bugg, Shah, Villareal, & Head, 2012; Erickson et al., 2009), and others not observing such associations (Honea et al., 2009; Niemann et al., 2014; Vidoni, Honea, Billinger, Swerdlow, & Burns, 2012). Differing results may be in part due to the method of obtaining hippocampal volume (e.g., manual tracing, automated segmentation), or the inclusion criteria for a valid VO 2peak test.…”

Impaired Adaptive Cellular Responses to Oxidative Stress and the Pathogenesis of Alzheimer's Disease

“…Colcombe et al showed that both gray and white matter increased in healthy older adults as a function of fitness level, but the same correlation was not seen in younger subjects (34). Also, cardiorespiratory fitness was shown to be positively correlated with medial temporal cortex volume in AD patients, but not in healthy controls, suggesting that cardiorespiratory fitness may modify AD-related brain atrophy (75). Most of the studies on fitness and cognition look at leisure time activities, but one study showed that work-related physical activity alone was not protective against dementia or AD later in life (141).…”

The effect of exercise intervention on cognitive performance in persons at risk of, or with, dementia: A systematic review and meta-analysis

“…Physical activity that targets cardiovascular fitness (peak VO 2 ) may offer neuroprotective benefits and attenuate the neuronal structural and functional changes that are associated with MCI and dementia [15][16][17]. Evidence from animal models has demonstrated that aerobic exercise can increase neurogenesis, angiogenesis, learning, and memory in rats [18,19] and inhibit the progression of Alzheimer's-related neuropathology in mice [20].…”