What do small sticks used to start a fire have to do with bipolar moods?
Not much… Kindling in the context of this post refers to a phenomenon that is well documented in some people with seizure disorders and which may have relevance to some people with bipolar moods.
Bob Post, who was for many years Chief of the Biological Psychiatry Branch at the National Institutes for Mental Health in Washington, DC, and is probably one of the most influential writers about bipolar moods, came up with the idea that bipolar moods and seizures might share certain traits. His theory led to the discovery that many medications that were prevented seizures (valproate or Depakote, lamotrigine or Lamictal, carbamazepine or Tegretol) also helped to prevent extreme mood swings.
In the diagram below, from a recent article he wrote on kindling, you can see in a nutshell the similarities he found between bipolar mood episodes and seizure disorders.
In both seizure disorders and bipolar moods there seemed to be a worsening with each untreated episode (this is the kindling phenomenon, each episode sets up the brain to be more vulnerable to the next). Effective treatment in both cases could stop this progression. In some cases there was the development of tolerance (a medication that had been working stopped working). And finally the goal of treatment, he proposed, was the same for both conditions – remission, meaning the absence of episodes, because only with sustained remission could this progressive worsening of the condition be halted (the brain could begin to heal itself).
It is a compelling story, and one that also led to the development of effective treatments, but for many reasons it is controversial. Tom Wootton, who has written and spoken a lot about bipolar, specifically targets this theory when he expresses concern about “psychiatry’s” view of bipolar. Embedded in the notion is the belief that bipolar moods are things to be avoided at all costs (like seizures).
I have been ambivalent about the model. For one thing, it does not explain the well documented improvement in symptoms that most people experience in middle age or older age. However I recently got to thinking about it again in the context of a young man who had seemed to be doing so well, and has now become resistant to almost all treatment.
He became psychotic, and had to go to a psychiatric hospital (a very rare event in my practice). While he was in the hospital there were a series of events that seemed to follow the kindling pattern – his medications were changed, and then he refused medications for a period of time, and each time he reentered that psychotic manic state it became harder to get him out of it.
Here is how the kindling hypothesis might relate. You can see that in someone with a seizure, the fact of 
having had one seizure (an “event”) can lead to a prolonged period when that person is “sensitized” (more vulnerable to another event). If something triggers another event during the vulnerable period the next seizure (or event) is more severe. In epilepsy, this can lead to what is called “status epilepticus” or intractable seizures. In bipolar perhaps this phenomenonleads to rapid cycling (moods that cycle up and down without any breaks).
This process, by the way, is typical of many cells in the body (for example something analogous to kindling is responsible for severe heart arrhythmias – a signal comes in to trigger a discharge in the heart’s pacemaker cells during a period before that cell has fully recovered from the previous heartbeat, and this leads to prolonged disruption in the heart’s normal rhythm.
For this young man the hypothesis suggests that the most important thing to do right now is to get control of the mood swings, and let the brain heal itself. And this might mean higher doses of medication for a short period.