The phenomenon of kindling in epilepsy was first discovered by accident by researcher Graham Goddard in 1967. Goddard was studying the learning process in rats, and part of his studies included electrical stimulation of the rats' brains at a very low intensity, too low to cause any type of convulsing. What he found was that after a couple of weeks of this treatment, the rats did experience convulsions when the stimulation was applied. Their brains had become sensitized to electricity, and even months later, one of these rats would convulse when stimulated (History, 1998). Goddard and others later demonstrated that it was possible to induce kindling chemically as well (Hargreaves, 1996.)
The name "kindling" was chosen because the process was likened to a log fire. The log itself, while it might be suitable fuel for a fire, is very hard to set afire in the first place. But surround it by smaller, easy to light pieces of wood - kindling - and set these blazing, and soon the log itself will catch fire. Dr. Robert M. Post of the National Institute of Mental Health (USA) is credited with first applying the kindling model to bipolar disorder (NARSAD). Demitri and Janice Papolos, in their excellent book The Bipolar Child, describe this model as follows:
- ... initial periods of cycling may begin with an environmental stressor, but if the cycles continue or occur unchecked, the brain becomes kindled or sensitized - pathways inside the central nervous system are reinforced so to speak - and future episodes of depression, hypomania, or mania will occur by themselves (independently of an outside stimulus), with greater and greater frequency.
Thus, many researchers now believe that kindling contributes to both rapid cycling and treatment-resistant bipolar disorder, and this model also is consistent with cases where cycling began with definite mood triggers, stressful or exciting events, and later became spontaneous.
In addition, it has been shown that substances such as cocaine and alcohol have their own kindling effects which can contribute to bipolar kindling. In fact, it was the knowledge that cocaine causes seizures that led Dr. Post to connect kindling in epilepsy with mood disorders, after he had studied the unexpected effects of cocaine on severely depressed patients (NARSAD). A study led by Dr. Joseph Goldberg found that patients diagnosed with both bipolar disorder and substance abuse were much more likely to respond to treatment that included an anticonvulsant/mood stabilizer, divalproex (Depakote) or carbamazepine (Tegretol), with or without Lithium, than treatment with Lithium alone. At the same time, patients who had bipolar disorder but no history of substance abuse had similar remission rates with both types of treatment. Dr. Goldberg did note that more controlled studies are needed on the role of anticonvulsants in treating dual diagnosis patients. (Substance Abuse, 2000)
Works CitedThe History of Epilepsy. (1998). Accessed 9/16/00. No longer available.
Hargreaves, Eric L. The Neuroplasticity Phenomenon of Kindling. [Online]. Accessed May 5, 2000. No longer available.
NARSAD Research Newsletter. (Undated). Manic and Depressive Recurrences: The Search for Mechanisms and Treatments: A Profile of Robert M. Post, M.D. [Online]. Accessed September 16, 2000. No longer available.
Papolos, D. & Papolos, J. (1999). The Bipolar Child (pg 53). New York, NY: Broadway Books.
Expert Knowledge Systems LLC. (1997). Expert Consensus Treatment Guidelines for Bipolar Disorder: A Guide for Patients and Families. [Online]. Accessed September 16, 2000.
Bipolar Disorders Letter. (May 2000). Substance Abuse History Complicates Treatment of Bipolar Patients. [Online]. Accessed September 17, 2000. No longer available.
Phelps, J., M.D. (2000). Treatment Details: Does bipolar disorder get worse over time? (the "kindling" theory). [Online]. Accessed September 17, 2000. As a result of many studies involving the kindling model, many researchers now stress the need for early and aggressive treatment of bipolar disorder, to prevent the brain from becoming more and more sensitized and going into rapid cycling or treatment resistant manic depression. A 1999 study also indicated that a significantly higher percentage of dual diagnosis patients had a history of medication noncompliance - which could suggest that kindling had more time to take place when no medication was being taken. (Substance Abuse, 2000)
What does all this mean for the bipolar patient?
- Take your medications as prescribed. Stopping treatment now could make your condition actually worsen and become more difficult to treat in the future.
- If you have not been diagnosed but feel you may be manic depressive, seek treatment, the sooner the better.
- Be honest with your prescribing doctor if you have an alcohol or drug problem, so he or she can evaluate your medication therapy accordingly.