The effects of aerobic exercise on the structure and function of DMN-related brain regions: a systematic review

Abstract

Physical activity may play a role in both the prevention and slowing of brain volume loss and may be beneficial in terms of improving the functional connectivity of brain regions. But much less is known about the potential benefit of aerobic exercise for the structure and function of the default mode network (DMN) brain regions. This systematic review examines the effects of aerobic exercise on the structure and function of DMN brain regions in human adulthood. Seven electronic databases were searched for prospective controlled studies published up to April 2015. The quality of the selected studies was evaluated with the Cochrane Collaboration's tool for assessing the risk of bias. RevMan 5.3 software was applied for data analysis. Finally, 14 studies with 631 participants were identified. Meta-analysis revealed that aerobic exercise could significantly increase right hippocampal volume (SMD = 0.26, 95% CI 0.01-0.51, p = 0.04, I = 7%, 4 studies), and trends of similar effects were observed in the total (SMD = 0.12, 95% CI -0.17 to 0.41, p = 0.43, I = 0%, 5 studies), left (SMD = 0.12, 95% CI -0.13 to 0.37, p = 0.33, I = 14%, 4 studies), left anterior (SMD = 0.12, 95% CI -0.16 to 0.40, p = 0.41, I = 74%, 2 studies) and right anterior (SMD = 0.10, 95% CI -0.17 to 0.38, p = 0.46, I = 76%, 4 studies) hippocampal volumes compared to the no-exercise interventions. A few studies reported that relative to no-exercise interventions, aerobic exercise could significantly decrease the atrophy of the medial temporal lobe, slow the anterior cingulate cortex (ACC) volume loss, increase functional connectivity within the hippocampus and improve signal activation in the cingulate gyrus and ACC. The current review suggests that aerobic exercise may have positive effects on the right hippocampus and potentially beneficial effects on the overall and other parts of the hippocampus, the cingulate cortex and the medial temporal areas of the DMN. Moreover, aerobic exercise may increase functional connectivity or activation in the hippocampus, cingulate cortex and parahippocampal gyrus regions of the DMN. However, considering the quantity and limitations of the included studies, the conclusion could not be drawn so far. Additional randomized controlled trials (RCTs) with rigorous designs and longer intervention periods are needed in the future.

Polygenic risk has an impact on the structural plasticity of hippocampal subfields during aerobic exercise combined with cognitive remediation in multi-episode schizophrenia

“…A recent meta-analysis revealed that aerobic exercise increases hippocampal volume. 15 However, studies in schizophrenia have found different results for the effects of aerobic exercise on hippocampal structure, probably because the resolution of the acquired structural MRI data was lower and the human brain is subject to high variability in function, structure and response. 92 , 93 , 94 Furthermore, we did not use a randomization procedure to allocate the schizophrenia patients to the endurance training augmented with cognitive remediation or table soccer augmented with cognitive remediation group.…”

“… 11 , 12 , 13 , 14 Some of these studies provided evidence that aerobic exercise increases hippocampal volumes; this was recently confirmed by a meta-analysis. 15 However, there are also findings of no volume increase in the hippocampus 13 or even hippocampal volume decrease in the right hippocampal subfields cornu ammonis (CA)-2/3, subiculum and dentate gyrus (DG) after an intense aerobic intervention. 16 Volume loss correlated negatively with fitness improvement, indicating that decreased hippocampal volume was found mainly in those participants who did not benefit from the exercise program.…”

The Aerobic and Cognitive Exercise Study (ACES) for Community-Dwelling Older Adults With or At-Risk for Mild Cognitive Impairment (MCI): Neuropsychological, Neurobiological and Neuroimaging Outcomes of a Randomized Clinical Trial

“…Structural changes in certain regions of the brain have been found to follow exercise and are often linked to concomitant changes in cognition; for example, increases in the hippocampus (Lorens-Martín et al, 2009 ; Erickson et al, 2011 ), as well as the anterior cingulate cortex, dorsal lateral prefrontal cortex, and more broadly the prefrontal cortex (ACC, DLPC, and PFC; Gordon et al, 2008 ; Erickson et al, 2011 ; Weinstein et al, 2012 ; Curlik and Shors, 2013 ; Hayes et al, 2013 ; Nishiguchi et al, 2015 ; ten Brinke et al, 2015 ; Jonasson et al, 2017 ; Li et al, 2017 ). While the body of research has been growing with respect to linking physical exercise and cognition via biomarkers, scant literature has yet explored how these indicators and mechanisms react in the case of combined or interactive mental and physical exercise interventions in humans, wherein there might be somewhat differential or compounding beneficial effects given a two-for-one intervention (for a promising exception, see Eggenberger et al, 2016 ).…”

Higher Cardiorespiratory Fitness is Associated with Reduced Functional Brain Connectivity During Performance of the Stroop Task

“…Increasing exercise engagement is capable of increasing CRF and has also been shown to enhance brain plasticity in animal models [44,45] and in humans [46][47][48][49]. Higher CRF is also associated with better cognitive performance [50][51][52] and resting state functional connectivity [53][54][55][56] in cross-sectional studies and following exercise interventions.…”