It's been suggested to me that I may not have enough serotonin, which is causing my anxiety. How can I tell? Is there such a thing as too much serotonin in the body as well?
Serotonin is a class of neurotransmitters. They are simple molecules produced in synapses which are the connections between neurons.
And although it's serotonin that triggers the neuro receptors which fires the second neuron, there are about 10 other mechanisms involved within that synapse that determine how often serotonin is produced and reuptaken (mopped up), how often the receptor is blocked etc.
Furthermore, serotonin affects various parts of the body and even parts of the brain differently.
These are not automatic functions. They are strongly influenced by your thoughts. If you think happy thoughts, you may produce more serotonin. We won't know until there is a test for serotonin levels.
There is no scientific evidence whatsoever that any group of people have serotonin deficits. If you don't believe me, ask your doctor to produce some.
All the evidence comes from drug trials on SSRIs.
SSRIs are Selective Serotonin Reuptake Inhibitors. This term was coined by SmithKline Beecham.
Let's work from the end:
All psychiatric drugs are inhibitors or agonists. Inhibitors block some process - here the reuptake (mopping up) of certain types of serotonin molecules. What this means is that serotonin stays around in the synapse much longer than it otherwise would. Therefore the concentrations of serotonin increase dramatically.
Now, because of the complexity of a single synapse, any change in the levels are serotonin are automatically compensated by the 10 or so other mechanisms. The only way to induce a major change is to overload beyond the system's capacity to self-regulate.
So you can absolutely have too much serotonin in your brain. It's a well documented iatrogenic (medically induced) problem called Serotonin Syndrome.
One consequence of this self-regulation is a reduction of the number of serotonin receptors in the brain. Therefore, taking SSRIs is actually limiting your ability to be happy in the medium term. This is why they can be (despite what you've been told) addictive.
Serotonin doesn't just affect your emotions. It affects your appetite, muscles, immune system etc.
All SSRIs have the same side effects. They are not side effects of the drug, but rather this overloading of the system.
SSRAs are a newer class of drug which have the exact opposite neurobiological effect from SSRIs. They accelerate reuptake (reduce serotonin levels) rather than inhibit reuptake (increase serotonin levels). So that's going to make you depressed, right?
Wrong - it actually relieves depression. No information yet regarding the effects on people who are anxious..
As Dr David Healy writes:
The fact that companies have chose to market them as antidepressants rather than agents that cause agitation is a business decision rather than a scientific matter. It is certainly not one that was "ordained by God." You could say that the fact that some people who are depressed get better is a side effect.
At extreme levels of agitation thoughts of suicide increase, especially with Paroxetine.
Other side effects include loss of libido, loss of appetite & sleep disruption.