Scopolamine's Anticholinergic Effects on EEG Spectral, Aperiodic, Complexity, Microstates, and Heart Rate...

Area of Science:

• Neuroscience
• Pharmacology
• Psychiatry

Background:

• Scopolamine, a muscarinic antagonist, disrupts central cholinergic mechanisms, affecting EEG and cognition.
• Peripheral effects on heart rate variability (HRV) by scopolamine are not well-defined.

Purpose of the Study:

• To investigate the acute central and peripheral effects of scopolamine on EEG and HRV.
• To define the concentration-effect relationship for scopolamine's impact on HRV.

Main Methods:

• Adults with depression and healthy controls received scopolamine or glycopyrronium infusions.
• EEG and electrocardiography were recorded for 4 hours post-infusion.
• EEG spectral, complexity, and microstate analyses were performed, alongside HRV and pharmacokinetic-pharmacodynamic modeling.

Main Results:

• Scopolamine increased delta power and altered EEG spectral parameters, correlating with drowsiness.
• Reduced Lempel Ziv Complexity and altered microstate durations indicated central nervous system changes.
• Scopolamine decreased HRV, with a delayed effect modeled via pharmacokinetic-pharmacodynamic relationships.

Conclusions:

• Scopolamine induces central EEG changes and peripheral HRV reduction, suggesting muscarinic mechanism disruption.
• These findings align with reduced excitation-inhibition and increased drowsiness, mimicking Alzheimer's-like cholinergic deficits.