Why do SSRIs take up to 2 weeks to kick in, but only 2-3 days to wear off?
In: Biology
Imagine an empty swimming pool being filled with a hose. To be allowed to dive, you must fill the pool to the 8 foot mark, so you put a plug in the drain. It takes many hours to fill up 8 feet of water. The water level needs to rise 8 feet, to reach the ‘effective level’.
It’s now 8′ 1″.
Someone removed the drain plug. The water level only needs to fall more than an inch before it goes below the ‘effective level, where it’s not allowed to dive.
Also, the drain is letting water out faster than the hose brings water in. So it only takes a few minutes before it’s not safe to dive again.
In this analogy, the SSR inhibitor is the drain plug.
The original theory is that it’s dependent on the rate your neurons are actually producing serotonin. Because it’s blocking reuptake and not just increasing the production of serotonin, it can take time for that to build up in the brain. However, at least according to the attending psychiatrist I worked for, this may not entirely be the case.
In essence, we’re not 100% certain. Newest theory is that in addition to the increase in serotonin levels in the brain (which actually happens fairly quickly. Probably less than the 2-4 weeks that it takes for serotonin to actually build up), it also has an effect on neuroplasticity, or how much your neurons can change their connections. Neural plasticity is higher in children than old people for instance, which is why they have an easier time learning new concepts. In essence it increases the serotonin, then hits reset on the neurons and allows them to form connections differently than they were when serotonin was low. The serotonin does wear off quickly once you stop taking them, so if you haven’t fully brought yourself out of the depressive state, you may fall back rather quickly.
The new theory is complex and hard to prove and uncertain. Neural plasticity is not particularly well understood. But who knows, maybe those researchers are right and that’s what’s really happening
They take 2 weeks to reach full effectiveness, before you’d consider changing a dose. After 2-3 days they are not effective enough to be good for you, but residual effects remain. You’re not measureing the same thing in the different timelines.
They prevent Serotonin from being destroyed in a sense to help you build up a stock pool of Serotonin in the brain which is dependent on your Serotonin creation to build that up which takes a few weeks to feel the effects where when you remove the SSRI it in a sense flushed out your stock pool of Serotonin and you’re back to baseline.
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