Researchers examined data from 26 clinical trials that randomly assigned some patients with a variety of chronic painful conditions to receive this therapy and others to get a placebo or dummy treatment or stick with usual care. Most of these trials were too small or brief to offer conclusive evidence that cranial electrical stimulation works for headache, joint pain, musculoskeletal pain, headache, fibromyalgia, insomnia, or depression alone, the analysis found.
For people with both depression and anxiety, however, researchers found "low-strength" evidence of a modest benefit. "If there is a benefit, it is probably not on average a large benefit, because when a treatment has an average benefit that is large this is usually pretty obvious even from a small number of studies or even studies of a small number of patients," said lead study author Dr Paul Shekelle, of the West Los Angeles Veterans Affairs Medical Center.
"But the benefit of cranial electrical stimulation does not have to be large for it to still be a useful additional option for treatment of these conditions, because for most of them we don't have large benefit treatment options," Shekelle said by email. With depression and anxiety in particular, four of the five studies in the analysis were conducted more than 40 years ago using shock therapy devices that are no longer available, researchers note in the Annals of Internal Medicine. In the largest and most current study, patients did report bigger reductions in depression and anxiety symptoms with shock therapy than with usual care that included antidepressants. But the study only enrolled 115 patients and lasted just five weeks.