Kindling hypothesis of depression
The kindling hypothesis of depression posits that each period of depression in someone with major depressive disorder (MDD) causes neurological changes that predispose the person to future episodes. While the first episode of depression is often triggered by major life events, future episodes are less likely to be tied to circumstantial factors.[1] There is some evidence to support the kindling hypothesis.[2]
A 2022 review in Cureus focused on similarities between MDD and fibromyalgia and argues for a role of kindling in both disorders.[3]