The Kindling Theory of Bipolar: Does One Episode Beget Future Episodes?
Does our bipolar get progressively worse over time? If left untreated, the answer is a resounding “yes” from the psychiatric profession. Let’s investigate …
The experts talk of “sensitization” and “kindling.” For instance, if you subject lab animals to stimulants or zap them in the amygdala, the repeated exposure sensitizes the brain to pronounced behavioral reactions in the first instance and kindles the brain into spontaneous seizures in the second.
This is reasoning by analogy, mind you, but the inference is clear: That first episode has changed the brain in a way that increases our risk for a second episode. As Robert Post, principal exponent of the kindling hypothesis, puts it: “Episodes beget episodes.”
In his 2008 book, Treatment of Bipolar Illness, Robert Post and co-author Gabriele Leverich cite the pioneering Emil Kraepelin, who observed that intervals between episodes grew shorter over time. Kraepelin also noted that stress was less of a factor in triggering later episodes.
The implication is that although environmental stresses may play a major role in initiating the first episode, after that the illness tends to take on a life of its own. Subsequent studies lend support to Kraepelin’s findings.
Post and Leverich go farther by suggesting that early treatment may lead to better long-term outcomes, while the brain is still reasonably resilient.
To further support their theory of kindling, the authors point to brain research that highlights BDNF, a protein in the neuron that plays a critical role in neural development and maintenance. When a mood episode occurs, the brain releases toxins that result in oxidative stress that decreases BDNF production in the neuron, particularly in the hippocampal region of the brain, associated with learning and memory.
In lab animals, we see depressive behavior. In depressed and manic humans, we find less BDNF in blood serum.
Interestingly, BDNF is also implicated in cocaine abuse. In this scenario, overproduction occurs in the VTA/accumens pathway, the part of the brain associated with pleasure and reward.
The authors suggest that over time, the repetition of mood episodes may affect the brain in two ways: First by compromising the brain’s ability to protect itself against repeated stress, and second by altering learning and memory and reward pathways in ways that set us up for future episodes.
In essence, the brain is sensitized or kindled to the point where even a minor disturbance - or no disturbance at all - may set us off.
The authors point out that a number of mood stabilizers increase BDNF and similar proteins. Moreover, by helping prevent - or at least delaying episodes - these meds keep a manageable situation from deteriorating into something much worse.
As the authors conclude: “We always knew that affective episodes are associated with enormous suffering, but now they are likely to be bad for the brain.”
Now that we’re reasonably clear on kindling, Goodwin and Jamison in the second edition to Manic-Depressive Illness (2007) add confusion to the matter by poking holes in the findings of Kraepelin and his successors. They conclude that at best these studies “suggest its relevance to at least some patients.”
Nevertheless, it would be foolish to believe our bipolar will simply go away if we leave it alone. Our illness takes no prisoners. Vigilance is the watchword.
Post and Leverich point to their own case studies showing the wisdom in staying on meds. In addition, we can cite a body of research extolling the benefits of meditation and yoga and other activities that are good for the brain.
This raises the issue of “neuroplasticity,” where we can be active partners in building our own better brains. Basically, physically restructuring the brain is not a one-way street to disaster, as kindling implies. Recent studies, for instance, point to meditation increasing the volume of the hippocampus and decreasing the size of the amygdala (involved in fight-or-flight).
After reading this, I urge you to check out my neuroplasticity articles listed below.
Basically, we are not stuck with the brains we were born with. On one hand, we need to protect ourselves against the worst that can happen to us. On the other, we need to set our sights on making us stronger. Be wise, be determined, live well …
John is an author and advocate for Mental Health. He wrote for HealthCentral as a patient expert for Depression and Bipolar Disorder.