Regional cerebral cortical thickness correlates with autonomic outflow

Area of Science:

• Neuroscience
• Autonomic Physiology
• Aging Research

Background:

• Autonomic nervous system (ANS) dysregulation, characterized by increased sympathetic and decreased parasympathetic outflow, is common in aging.
• The underlying mechanisms driving age-related autonomic dysfunction remain largely unknown.
• This study investigates the relationship between brain structure and autonomic control in aging adults.

Purpose of the Study:

• To test the hypothesis that individual differences in autonomic nervous system (ANS) outflow are associated with cerebral cortex thickness.
• To explore the role of medial prefrontal cortex (MPFC) and insula cortex thickness in regulating autonomic function across the adult lifespan.
• To determine if age influences the association between cortical thickness and autonomic outflow markers.

Main Methods:

• Assessed cardiovagal baroreflex sensitivity, heart rate variability, and muscle sympathetic nerve activity (MSNA) in 55 healthy adults (21-73 years).
• Measured cortical thickness using T1-weighted MRI scans, focusing on the MPFC and insula.
• Analyzed correlations between autonomic variables and cortical thickness, considering cardiorespiratory fitness (VO2peak) as a covariate.

Main Results:

• Cortical thickness in the MPFC showed strong correlations with multiple markers of autonomic outflow, including heart rate variability and MSNA.
• Specifically, MPFC thickness was associated with high-frequency power, SDNN, total power, burst frequency, burst incidence, and total MSNA.
• Left insula thickness was also associated with burst incidence, and the strength of these associations was age-dependent.

Conclusions:

• Cerebral cortex thinning, particularly in the frontal lobe (MPFC), contributes to age-related alterations in both sympathetic and parasympathetic nervous system activity.
• These findings highlight a neurobiological link between brain structure and autonomic control, offering insights into aging-related physiological changes.
• Autonomic dysfunction in aging may be partly explained by structural changes in specific cortical regions, independent of cardiorespiratory fitness.