Researchers have identified the mechanism by which valproic acid controls epileptic seizures, and by doing so, also revealed an underlying factor of seizures.
The drug protects the flow of potassium between neurons which is called the m current. During a seizure, the m current is inhibited, which allow the neurons to become too excitable. A seizure is the result.
Many people with bipolar disorder (including myself) also take valproic acid (divalproex/Depakote). The new mechanism explains how the drug helps with manic episodes, when neurons are hyperexcitable. But what about depression?
If manic episodes result from too little m current, perhaps depressive episodes occur due to too much m current. In that case, Depakote would work by limiting the m current.
This may sound contradictory, but if it is true, it is just one more example of homeostasis in the human body. Most conditions of the body — sleep, temperature, heart rate, growth of new cells, availability of nutrients such as protein — are best kept within a range of values that is generally the same for all people. One can have too much vitamin A or too little. Body temperature can be too low or too high.
Bipolar disorder results when the underlying factors (such as the m current) are not kept in balance, but swing wildly from one extreme to another. Drugs that adjust those underlying factors are potential treatments for bipolar.