Why do people get bipolar disorder? There are many theories abound. One of them of course, is neurotransmitter levels. We have epinephrine, norepinephrine, dopamine, serotonin and GABA (gamma a mini butyric acid.) Neurotransmitters are either derivatives of amino acids, or small peptides. Some of these are excitatory neurotransmitters and some are inhibitory. They are released by presynaptic neurons (yellow). The excitatory ones bind to the post synaptic neuron (green) across the synaptic cleft and make it easier for that neuron to fire thereby passing the nerve impulse and information along. The inhibitory ones make it harder for the next neuron to fire thereby stopping the nerve impulse.

It has been postulated that levels or metabolism of these neurotransmitters may be involved in mood disorders such as bipolar disorder or depression. It’s easy to imagine how a deficit in neurotransmitters may cause depression and possibly an overproduction or over activity of neurotransmitters may lead to mania.

There is also evidence that the Na+ (Sodium) pump that is involved in pumping Na+ out of neurons may be involved in mania. Lithium works at the site of the Na+ pump. Lithium is so similar to Na+, that when it given to patients, their intracellular Na+ concentration decreases. And that may be exactly how lithium exerts it’s mood stabilizing effect. The decrease in Na+ concentrations inside neurons leads to less firing of neurons. The less the firing, the less the signal, or information, or thought is propagated. The less activity in the brain, the less mania. That’s how I explain it to myself.