The Influence Of Depression On Relationships Between Fitness (aerobic And Muscular) And Cerebrovascular Hemodynamics

PURPOSE: Depression (DEP) is highly prevalent and may relate to cerebral blood flow (CBF), as impaired CBF is associated with greater DEP symptom duration and intensity. Aerobic and muscular fitness are associated with markers of CBF and may be important targets for improving DEP. Therefore, the purpose of this project is to explore how DEP may influence relationships between aerobic fitness and muscle strength with Middle Cerebral Artery (MCA) CBF measures (I.e., MCA mean Velocity (MCA V), MCA Pulsatility Index (MCA PI), MCA Conductance (MCA CON), MCA Cerebrovascular Reactivity (MCA CVR), and relative MCA Cerebrovascular reactivity (MCA CVR REL)). METHODS: Adults (n = 101) completed a single session consisting of physical and mental health questionnaires, CBF assessments, hand grip strength, and aerobic fitness assessments. Fitness was quantified via VO2max from an incremental VO2max fitness test, and muscle strength via a handgrip dynamometer. Self-reported DEP symptom severity was assessed via the Quick Inventory for Depressive Symptomatology (QIDS). Participants with a QIDS score > 6 (n = 18) were categorized as mild or greater DEP. Primary markers of CBF were assessed as resting MCA V, MCA PI, and MCA CON, with 8 paced breaths used to determine MCA CVR, and MCA CVR REL via transcranial doppler. Stratified linear regression analyses were conducted to evaluate relationships between fitness measures and each CBF variable by group. RESULTS: There was a significant relationship between VO2max and MCA V in healthy (t = 2.012, p = 0.047) but not in DEP adults (t = 1.421, p = 0.159). There was a significant relationship between VO2max and MCA CON in both healthy (t = 2.814, p = 0.006) and DEP adults (t = 2.465, p = 0.016). There were no significant relationships in either group for grip strength with any of the CBF outcomes or for VO2max with the other CBF outcomes (all p > 0.05). CONCLUSION: This suggests that a higher VO2max may be associated with improved MCA mean velocity and MCA conductance in healthy adults but that the relationship between VO2max and MCA mean velocity may be attenuated in depressed adults. Fitness levels are likely to still be an influential target for improving cerebrovascular health in adults with DEP, though the discrepant velocity and conductance findings warrant further research.