Physiological effects of electroconvulsive therapy and transcranial magnetic stimulation in major depression

Major depressive episodes ave associated with dysregulation of various phys iologic systems. Antidepressant medications alter regulation of the hormona l and sleep systems. A thorough understanding of these changes may elucidat e the pathophysiologic basis of the disorder [Amsterdam et al., 1989: Psych oneuroendocrinology 14:43-62] and interventions targeted directly at these systems are being increasingly recognized as possible treatments for depres sion [Wong et al, 2000: Proc Natl Acad Sci USA 97:325-330; Szuba et al., 19 96 Proc Am Coil Neuropsychopharmacol Ann Meet]. These physiologic systems a re regulated by the major neurotransmitters implicated in the etiology of m ood disorders-norepinephrine, serotonin, and dopamine. Many of the hormones of import for this article also act as neurotransmitters and thus alter ce rebral activity themselves [Owens and Nemeroff 1993: Ciba Found Symp 172:29 6-308; Weitzner; 1998: Psychother Psychosom 67:125-132] Parenteral infusion of hydrocortisone [DeBattista, 2000: Am F Psychiatry 157:1334-1337] and th yrotropin-releasing hormone (TRH) [Prange et al., 1972: Lancet 2:999-1002; Marangell et al., 1997: Arch Gen Psychiatry 54:214-222; Szuba, 1996: Proc A m Coil Neuropsychopharmacol Ann Meet.] produce acute antidepresent effects. Antagonists to corticotropin-releasing hormone and repeated parenteral inf usion of TRH may have antidepressant activity when given during several wee ks [Wong 2000: Proc Natl Acad Sci USA 97:325-330; Arborelius et ad., 1999: F Endocrinol 160:1-12; Callahan et al., 1997: Biol Psychiatry 41:264-272]. Manipulations of the sleep system through sleep deprivation can ameliorate depression [Szuba et at, 1994: Psychiatry Res 51:283-295; see Wirz-Justice et al., 1999: Bio Psychiatry 46:445-453 for review]. Sleep deprivation has been shown in more than three dozen studies published in the last three dec ades to produce marked acute antidepressant effects in the majority of depr essed individuals [Wirz-Justice, et al., 1999: Biol Psychiatry 46:445-453]. Thus, examination of the effects the two nonpharmacologic treatments, elec troconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS), pr oduce in these physiologic systems may help elucidate their mechanisms of a ction, while enhancing understanding of the neurobiology of depressive illn ess. We will review these physiologic changes associated with depression, t he effects that manipulations of these systems can have on depressive disor ders, and then describe the effects the two techniques that can stimulate t he human brain in vivo, ECT and TMS, exert on these systems. (C) 2000 Wiley -Liss, Inc.