Shealy, C. et al, Depression: A diagnostic, neurochemical profile and therapy with CES, J of Neuro. & Ortho. Med Surg. 10(4): 319-21, 1989.
Research was conducted with 4 groups: (1) “normal group”, (2) intractable chronic pain, (3) chronic pain with depression, and (4) longstanding depression unresponsive to medication.
Psychological tests, serotonin and cholinesterase levels were measured pre and post.
Depressed patients improved most with treatment; 60% reported improvement, 44% of the pain patients reported improvement. In the depressed patients, after treatment, both serotonin and cholinesterase levels improved significantly.