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Some researchers believe that in OCD sufferers have abnormalities or an imbalance in the neurotransmitter, or brain chemical, serotonin, which could be to blame for OCD. Serotonin is the chemical in the brain that sends messages between brain cells and is thought to be involved in regulating many functions from anxiety, to memory, to sleep which is why SSRIs are often used to treat OCD, although it is not fully known why the SSRI medications seem to help some people with OCD.
The brain is made up of millions of interconnected brain cells (neurons). Messages travel along these cells rather like electricity down a wire, but when the message reaches the end of the neuron, it has to jump the gap (synapse) to the next cell or group of cells. This is achieved by the neuron releasing tiny amounts of a neurotransmitter into the gap between the nerve cells.
Brain imaging studies have been used to show the differences between the brains of people with OCD and those without OCD, but the scientific community is split over whether what researchers have found is a cause for, or a result of, having the disorder.
How does the Brain Cells and Chemicals Work?
The job of your nerve cells is to send messages back and forth like a telephone wire. But nerves aren’t a single string — they’re made of lots of interconnected cells. So they act more like the game telephone, where one person whispers a message to the next, and it’s passed down to the end of the line one person at a time. Instead of words, the ‘message’ is passed by chemicals called neurotransmitters that are sent by one cell to the next in line.
These chemicals are sent out by one nerve cell into the space between it and the next cell. The next cell in line gets the message once those chemicals get to it from across the gap. Then that nerve cell releases a chemical toward the next nerve cell so it gets the message.
It’s important that the right amount of chemical is sent or the message might be heard wrong.
A key chemical involved in OCD is called serotonin. And a key gene for this process is hSERT. hSERT has the instructions for making a serotonin transporter. The transporter’s job is to sop up extra serotonin after a nerve spits it toward the next nerve cell in line. In some people with OCD, hSERT works too fast, and may collect all the serotonin before the next cell has even heard the signal! Their nerves are whispering when they should be speaking out loud.
In order to allow the nerve to recover and receive the next message, and in order to replenish stocks of the neurotransmitter in the original neuron, ready to send the next message, the body has a clever way of removing the neurotransmitter from the receptors, and allowing it to be taken back into the originating nerve (re-uptake).
The SSRIs slow down the collection of serotonin by transporters like hSERT and the process of returning the serotonin to the end of the neuron it comes from. This means that serotonin stays in the space between the cells longer and increases the chances that the second cell will get the message. Which helps prevent some OCD symptoms.
Thus, the SSRIs work by allowing the body to make the best use of the reduced amounts of serotonin that it has at the time. In due course, the levels of natural serotonin will rise again, and the SSRI can be reduced and withdrawn.