What mechanism leads to "anticholinergic syndrome"?

Anticholinergic syndrome is primarily characterized by symptoms arising from the blockade of acetylcholine at muscarinic receptors, which can occur due to an overdose or increased sensitivity to anticholinergic agents. These agents inhibit the action of acetylcholine, diminishing its effects on the parasympathetic nervous system, leading to symptoms such as dry mouth, blurred vision, tachycardia, urinary retention, and confusion.

When someone is exposed to a higher-than-normal dosage of these medications or has heightened sensitivity, the resulting anticholinergic effects are intensified, leading to the clinical presentation known as anticholinergic syndrome. Therefore, understanding the relationship between the dosage or sensitivity to these agents provides insight into the mechanism behind this syndrome.

In contrast, other mechanisms listed in the options do not directly contribute to the phenomenon of anticholinergic syndrome. Inhibition of acetylcholine release would suggest a different pathway, reduced norepinephrine levels and increased serotonin levels involve neurotransmitter systems that are not primarily linked to the anticholinergic effects experienced during an overdose of anticholinergic drugs.