Cardiorespiratory Fitness And Brain Structures - The Finger Study

Abstract

Executive processes and frontal cortical regions supporting them show notable changes with age. Structural magnetic resonance imaging studies have revealed a positive relationship between cardiorespiratory fitness (CRF) and brain volume in several cortical regions and in the medial temporal lobe. However, previous studies have been mainly focused on cognitively intact subjects. Furthermore, no sex differences have been reported. PURPOSE: To investigate whether CRF is associated with total gray matter (GM) and white matter volumes as well as medial temporal lobe and striatum volumes in a population-based sample of subjects with increased risk of Alzheimer’s disease. We also examined the role of sex in the association of CRF with brain volumes. METHODS: We used baseline data from the FINGER study. Participants had elevated CAIDE Dementia Risk Score. Inclusion criteria was set to select persons with cognitive performance at the mean level or slightly lower than expected for age according to Finnish population norms. Our substudy included 68 randomly selected individuals (39 men and 29 women) with 61-75 years of age. Cardiorespiratory fitness was assessed as peak oxygen consumption (VO2peak, ml/kg/min) measured directly in a symptom-limited maximal exercise test on cycle ergometer. Structural imaging was performed using a 1.5-Tesla scanner. Volumetric segmentation was performed with the Freesurfer automated image analysis suite. All brain volumes were expressed as ratios after normalizing by the total intracranial volume. RESULTS: In whole group, VO2peak was associated with left caudate volume (β=0.32, p=0.03), cortical GM volume (β=0.37, p=0.01) and total GM volume (β=0.40, p=0.007). In men, VO2peak was associated with cortical GM volume (β=0.61, p=0.001) and total GM volume (β=0.59, p=0.001). In women, VO2peak was associated with the left caudate volume (β=0.49, p=0.04). Peak oxygen consumption accounted for 23 and 1 percent of total variance of cortical GM volume in men and women, respectively. Likewise, VO2peak accounted for 25 and 4 percent of total variance of total GM volume in men and women, respectively. CONCLUSION: Cardiorespiratory fitness is associated with cortical and total gray matter volumes in elderly men with increased risk for Alzheimer’s disease.