Figure 1.

Proposed synergism between inflammatory stimulation and neurotrophic factors during multi-session treatment with electroconvulsive therapy (ECT). Before the first ECT session, depressed patients show reduced neurotrophin levels. An allostatic inflammatory response is thus endogenously triggered, mainly in the periphery, providing suboptimal inflammatory stimulation to the brain. Each ECT session strongly activates the innate immune system in the short term (minutes to hours post session) and thereby further mobilizes neurotrophin expression. Multiple inflammatory bouts are, however, needed over time (inter-session intervals of days to weeks) to achieve optimal neurotrophin availability. Upon remission, endogenous inflammation has no allostatic purpose and therefore resolves.