American Board of Psychiatry and Neurology (ABPN) Practice Exam 2026 - Free ABPN Practice Questions and Study Guide

Blocking muscarinic cholinergic receptors can lead to a variety of physiological effects due to the role of acetylcholine in the body, particularly in the parasympathetic nervous system. Muscarinic receptors are involved in numerous bodily functions, including smooth muscle contraction, glandular secretion, and modulation of heart rate.

Improvement in Alzheimer's symptoms is linked to the action of acetylcholine, which is typically in deficit in individuals with Alzheimer's disease. Many treatments for Alzheimer's aim to enhance cholinergic activity and increase acetylcholine levels in the brain, which can help alleviate some cognitive symptoms. Therefore, the blockade of muscarinic receptors would not lead to an improvement in Alzheimer's symptoms; instead, it would likely worsen cognitive conditions related to cholinergic deficiency.

In contrast, blockade of these receptors can lead to difficulty urinating due to reduced bladder contraction, dry mouth as a result of diminished salivary gland secretion, and blurred vision due to paralysis of the ciliary muscle, which is necessary for accommodating the lens of the eye. These effects reflect the broad role of muscarinic receptors in regulating smooth muscle activity and glandular secretion throughout the body.