Which of the following is NOT a sign of increased acetylcholine levels?

Increased acetylcholine levels are associated with various physiological responses, many of which are linked to the activation of the parasympathetic nervous system. Salivation, lacrimation, and muscle weakness can all occur as a result of excessive acetylcholine activity.

Salivation and lacrimation are classic examples of cholinergic effects, where an increase in acetylcholine leads to heightened secretion in glands. Muscle weakness can occur due to the disruption of normal neuromuscular transmission, often seen in conditions like myasthenia gravis which is characterized by autoantibodies affecting acetylcholine receptors.

Weight gain, on the other hand, is not directly associated with elevated acetylcholine levels. In fact, elevated levels of acetylcholine are more likely to stimulate metabolic pathways that may lead to increased energy expenditure rather than retention. Therefore, among the options provided, weight gain is the condition least likely to be a sign of increased acetylcholine and is, consequently, the correct choice.