Physical fitness and age-related differences in cognition and cortical thickness in young adulthood.

Abstract

The association between physical fitness and age-related differences in cognition and brain structure has been studied fairly extensively during development and aging, yet comparatively less in young adulthood. The current study examined 1195 young adults aged 22 to 36 (54% female; 67% Caucasian) to better understand associations between physical fitness-grip strength and submaximal cardiovascular endurance-and agerelated differences in executive function (EF), memory, and average cortical thickness. EF, memory, and cortical thickness were negatively associated with age, and higher endurance was positively associated with EF and memory. Neither physical fitness measure associated with cortical thinning. To follow-up on these analyses, data from monozygotic (n=149 pairs) and dizygotic (n=93 pairs) twins were used to estimate the degree to which heritability versus environment might contribute to the observed associations between cognition and endurance. Environmental effects shared by monozygotic and dizygotic twins alike were estimated to account for roughly 50% of the correlation between endurance and cognition (EF and memory). Heritability and non-shared environmental effects were inconsistent across EF and memory. Overall, these findings suggest an association between cardiovascular endurance and age-related differences in cognition in young adulthood and that these associations may be independent of cortical thinning. Whereas there was consistent evidence for a moderate contribution of the shared environment, there was limited and inconsistent evidence for a role of heritability.

Relationships between physical activity, healthy eating and cortical thickness in children and young adults

“…Some studies reported that greater cardiorespiratory tness was associated with greater overall cortical thickness in children (Esteban-Cornejo et al, 2019;Ross et al, 2015); however, other studies found that more t children (children that were > 70th percentile of VO 2 max) vs. less t children (< 30th percentile of VO 2 max) or those that underwent an after school PA intervention vs. children in a control wait-list group showed lower cortical thickness in the superior frontal cortex, superior temporal areas, and lateral occipital cortex (Chaddock-Heyman et al, 2015, 2021. Similar inconsistencies in the relationship between PA, exercise, and aerobic tness and cortical thickness were also observed in studies of young adults (Best, 2020;Stern et al, 2019;Williams et al, 2017). Some studies demonstrated that engagement in PA was correlated with cortical thinning (Williams et al, 2017), while others reported positive associations between aerobic exercise and increased cortical thickness (Stern et al, 2019), and others found no associations between either PA or aerobic tness and cortical thickness in young adults (Best, 2020).…”

“…Similar inconsistencies in the relationship between PA, exercise, and aerobic tness and cortical thickness were also observed in studies of young adults (Best, 2020;Stern et al, 2019;Williams et al, 2017). Some studies demonstrated that engagement in PA was correlated with cortical thinning (Williams et al, 2017), while others reported positive associations between aerobic exercise and increased cortical thickness (Stern et al, 2019), and others found no associations between either PA or aerobic tness and cortical thickness in young adults (Best, 2020).…”

“…The bene ts of healthy lifestyle behaviors, such as engagement in PA and consumption of healthy diets, have been demonstrated for cognitive, metabolic, and mental health outcomes across childhood and adulthood (Best, 2020;Geertsen et al, 2016;Rodriguez-Ayllon et al, 2018;Schmitz et al, 2002;Tyson et al, 2010). A growing body of research from neuroimaging studies suggested that the bene ts of healthy lifestyle may extend into neural markers of brain health, typically operationalized through measurements of brain structure such as volume and cortical thickness.…”

Associations Between Physical Fitness and Brain Structure in Young Adulthood

“…Other YA-HCP analyses have shown that BMI correlates with cortical thickness, with the direction (negative versus positive) depending on the region and hemisphere (Vainik et al, 2018). In a recent study using the YA-HCP, we failed to observe an association between cortical thickness and either submaximal cardiovascular endurance or grip strength (Best, 2020). Like other studies in the field, our previous study was limited by focusing on only one type of brain structure (specifically, cortical thickness), despite knowledge that GM structure is distinct from WM structure, and even that cortical thickness is genetically and phenotypically distinct from cortical area (Winkler et al, 2010).…”

“…Assuming that genetic overlap approximates 100% in monozygotic twins and 50% in dizygotic and non-twin pairs, behavioral genetic analyses can be conducted to estimate the heritability and environmental contributions to variation in fitness and brain structure, as well as the covariation between the two (Grasby et al, 2017). Previous research has found a moderate heritability contribution to the correlation between cardiovascular endurance and executive function (Best, 2020) and between BMI and executive function, cortical thickness and medial temporal lobe volume (Vainik et al, 2018). Research in other samples has shown a moderate heritability contribution to the BMI-executive function correlation in youth (Wood et al, 2019) and a more modest heritability contribution to the cardiovascular fitness-intelligence association among young men enlisted for military service (Aberg et al, 2009).…”