Feeling Lightheaded: The Role of Cerebral Blood Flow

Summary & key facts

Researchers tested 33 healthy people to see how lightheadedness and brain blood flow are linked. During hyperventilation that lowered CO2, people's reports of lightheadedness matched drops in cerebral blood flow velocity (CBFv). After a few such episodes, a smell that had been paired with hyperventilation later triggered more lightheadedness and a "feeling unreal" even though CO2 and CBFv did not change, suggesting the cause of the symptom can shift from blood-flow changes to perceptual or cognitive processes and that altered blood flow is unlikely to be the main trigger for repeated lightheadedness.

Key facts:

• The study included 33 healthy participants (N = 33).
• Each participant completed three hypocapnic (low-CO2) overbreathing trials and three normocapnic overbreathing trials in a semirandomized order, with each trial type paired with a specific odor.
• Cerebral blood flow velocity (CBFv) was measured in the right middle cerebral artery using transcranial Doppler ultrasonography (TCD).
• During the hypocapnic overbreathing trials, self-reported lightheadedness was closely related to changes in CBFv.
• In later normocapnic trials, the odor that had been paired with hyperventilation caused more reported lightheadedness and more reports of "feeling unreal," but these complaints occurred without changes in end-tidal CO2 or CBFv.
• The authors state that after a few episodes the mechanism behind lightheadedness may shift to perceptual-cognitive processes, and that altered cerebral blood flow is unlikely to be the primary trigger for recurrent lightheadedness.

Abstract

The results show that lightheadedness is associated with changes in CBFv but that after a few episodes, the underlying mechanism for this symptom may shift to perceptual-cognitive processes. These findings may help to understand why lightheadedness occurs during emotional distress and panic. In addition, altered cerebral blood flow is unlikely to play a primary precipitating role in recurrent symptoms of lightheadedness.

Topics

Heart Rate Variability and Autonomic Control Pain Management and Placebo Effect Psychosomatic Disorders and Their Treatments

Categories

Health Sciences Medicine Psychiatry and Mental health

Tags

Cardiology Cerebral blood flow Feeling Medicine Neuroscience Psychology Social psychology