@bulldogsandbruins 1072 wrote:

Can it be tested for? If low, how do you treat?

Acetylcholine, depending on the location of the neurons and types of receptors, may either increase or decrease dopamine. Stimulating acetylcholine nicotinic receptors may lead to an increase in dopamine. Stimulating acetylcholine muscarinic receptors may lead to a decrease in dopamine signaling.

Dopamine is the primary signal for libido.

There is no test currently for acetylcholine signaling other than a test for acetylcholine receptor antibodies – designed for the assessment for Myasthenia Gravis.

Some illnesses, such as schizophrenia, include suboptimal acetylcholine signaling as part of the pathophysiology of the illness. A symptom of this or sign of this is cigarette smoking. Nicotine is like an artificial acetylecholine, working on acetylcholine nicotine receptors. Patients essentially self-medicate to alleviate problems with this signaling system in their illness.

If I want to increase acetylcholine signaling, I would prescribe an acetylcholinesterase inhibitor. Since acetylecholine can decrease dopamine signaling, a side effects of this treatment includes loss of libido and depression.