Kindling: mood episodes get shorter and closer together – or do they?

July 22, 2007

If you stimulate rats’ brains once with a small electric shock, then they’ll be like “what the hell was that” and then go back to ratty things like munching on pellets.  If you keep doing that, eventually they’ll have a seizure in response to a shock. And if you keep that up, eventually they’ll start having seizures without you shocking them, and they’ll have them more and more easily in response to less and less provocation.  The original research was done by Dr. Graham Goddard in 1967, so this knowledge has been around a while. You can also do this to rats and humans with repeated exposures to some pesticides (says Wikipedia).

This is the idea behind “kindling” in both epilepsy and mood disorders.  I’m going to talk about mood disorders, and about research done surrounding kindling in mood disorders.  The Wikipedia article on epilepsy claims that role of kindling in human epilepsy is hotly debated.  I don’t know enough to follow up on that, but it might be interesting, given what we know about kindling in bipolar.

The idea in bipolar disorder is because of kindling that episodes become more frequent over time, with well periods between the episodes becoming shorter (this doesn’t include the episodes being more severe, which I had associated with the notion of kindling).  Kindling is often considered to be halted or reversed by medication, and efforts to communicate this to people has probably spared them and others a great deal of pain.  (Sadly, sometimes people are more responsive to the notion of potential brain damage than to the pain they’re causing in their lives and the lives of others.)

Now. It is absolutely true that untreated bipolar will fuck up your life (and other peoples’ lives – when someone decides not to take medication, they’re deciding that the people around them will continue to experience the consequence of their untreated disorder.  treatment is never a decision just about the individual).  And bipolar does rot your brain.

But it looks like the evidence for closer, more frequent episodes over time in all bipolars is limited and contradictory, as is the evidence that medication will help with it.  However (summary from Goodwin & Jamison; I looked through some primary source material and it wasn’t any more conclusive):

1) People have decreasing length of well intervals mostly for their first three episodes (Kessing et al 2004; Zis et al 1980; Angst & Selloro, 2000) up until one per year (Zis et al, 1980; another study they refer to as “Goodwin” but I can’t find in the text).  (The rapid-cycler in me says ha ha, one episode a year, let’s try one a week – and it is true that not everyone is well-represented by the average finding.)

2) Some but not all studies find that a subgroup of people with bipolar disorder (25-50%) have more frequent episodes over time (Goldberg and Harrow, 1994; Roy-Byrne et al, 1985, Kessing et al 1998).

3) Many studies find no evidence for shortening of well intervals over time (Winokur et al 1993, Turvey et al 1999, Tohen et al 2003).

4) Poor outcome was not found to be associated with shortening of well intervals over time, but with snapping directly from mania to depression or vice versa (Winokur et al 1993, Turvey et al 1999; Bratfos & Haug 1968; Angst et al 1973)
So: decreasing well intervals for the first three episodes up to about one episode per year.  And maybe a subgroup that has increasing frequency of episodes after that.

Goodwin and Jamison do note something I thought was really interesting: Post et al (1986, 1990), proposed the kindling hypothesis only for a subset of people with bipolar disorder: those who are unresponsive to lithium but respond to anticonvulsants (and have other non-classic-bpI-type symptoms).  Which makes the port of the concept over from epilepsy make more sense.  And Goodwin and Jamison say that *that* hypothesis is not inconsistent with the available literature.  (I’ll try to follow up on that later.)

As a moderator for a support forum heavily populated by people with bipolar disorder, I feel uncomfortable with this post.  I thought about it a lot before deciding to post it.  I don’t want to make getting adequate treatment less attractive.  On the good side, though, the research suggests that a lot of people are less likely to have have shorter well intervals with inadequate treatment or no treatment, and that’s a good thing for people with treatment-resistant bipolar and for people who won’t get treatment and the people who have to be around them.

But I’m posting it because it’s science and it’s relevant to what we know about what’s likely to happen to us.  And because it’s interesting.

I do want to say: No kindling doesn’t mean that untreated mood episodes won’t get worse…just that they won’t get closer together after the first few.  No kindling doesn’t mean no brain damage.  And no kindling doesn’t mean that no bipolar-aggravated life problems accumulating over time.  No kindling doesn’t mean that you’re not making other peoples’ lives miserable too.  And on and on…