Don't just google. Why not rely on some evidence based stuff rather than some opinionated hack like chris kresser, who by the way is an acupuncturist. Not what I would say clinical research.
Here are some more authoritative works and peer reviewed articles including from the Harvard Medical School, Lancet, Clinical Psychiatry etc
Nevertheless, it seems that biological influences are involved in the ætiology of affective disorders, and possibly they include cholinergic and adrenergic factors.
Current evidence suggests that the initial receptor and neurotransmitter effects of antidepressants lead to "downstream" changes in protein production at a cellular level; these changes in turn appear to influence elements of neuronal protection and synaptic plasticity [1]. Modern psychopharmacologic research has capitalized on this information, leading to the development of "designer" antidepressants with effects on specific combinations of selected neurotransmitter and neuropeptide system
