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Cerebral vasodilation and vasoconstriction associated with acute anxiety
R J Mathew1, W H Wilson, D Humphreys
1Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27710, USA.
Biological Psychiatry
|April 1, 1997
Summary
Generalized anxiety disorder patients showed reduced cerebral blood flow (CBF) responses to carbon dioxide (CO2) inhalation, especially those with severe anxiety. This suggests sympathetic nervous system activation may limit vasodilation during anxiety.
Area of Science:
- Neuroscience
- Psychiatry
- Cardiovascular Physiology
Background:
- Generalized anxiety disorder (GAD) is associated with altered autonomic nervous system function.
- Cerebral blood flow (CBF) regulation is crucial for brain function and can be influenced by stress and anxiety.
Purpose of the Study:
- To investigate the relationship between anxiety levels and cerebral blood flow (CBF) response to hypercapnia in patients with generalized anxiety disorder (GAD).
- To explore the potential role of sympathetic nervous system activation in modulating cerebrovascular reactivity during anxiety.
Main Methods:
- A randomized, between-groups, repeated measures design was employed.
- Cerebral blood flow (CBF), rating scales, and physiological indices were measured in GAD patients and controls.
- Participants underwent 5% CO2 inhalation with epinephrine or saline infusions under resting conditions.
Main Results:
- Subjects were categorized based on anxiety changes: decreased, mild increase, and severe increase.
- The most pronounced CBF increase during CO2 inhalation was observed in the group with decreased anxiety.
- The group experiencing a severe anxiety increase exhibited the least CBF response to CO2.
Conclusions:
- Restricted hypercapnic cerebral vasodilation in severe anxiety may be mediated by cervical sympathetic fibers.
- Sympathetic activation, similar to findings in animals, appears to limit cerebrovascular response to CO2 during heightened anxiety.
- These findings highlight a potential mechanism linking anxiety, sympathetic activity, and impaired cerebral blood flow regulation.
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