Is depression associated with low levels of neurotransmitter? which one?

Some depression is: Serotonin plays an important role in feelings of well-being vs depression. Low levels can trigger depression and other disorders. Other neurotransmitters involved in depression include acetylcholine & catecholamines (dopamine, norepinephrine, & epinephrine). As well as corticotropin-releasing factor (crf), a stress hormone may be involved. But not all depression is chemically caused.

Depression is a: Descriptive term for a set of symptoms. Although drugs that boost certain neurotransmitters are often helpful, there is little if any evidence that depression is caused by any neurotransmitter deficiency any more than a headache is cause by an Aspirin deficiency. Genetics, life circumstances & negative thinking patterns contribute to depression, but a precise cause is unknown.