“No convincing evidence” that depression is caused by low serotonin levels
SSRIs raise extra-synaptic serotonin levels within the first hour of taking them. However, their efficacy against depression takes weeks or even months to manifest. We&#x27;ve known this for decades, and as a result the &quot;chemical imbalance&quot; theory of depression hasn&#x27;t been a real contender in depression research for a long, long time.<p>The key thing to understand is that serotonin levels don&#x27;t have to be low for SSRIs to induce positive changes. SSRIs don&#x27;t just &quot;raise serotonin levels&quot; as many have come to believe, but rather change the dynamics of serotonin in the brain. This produces downstream changes that, over time, can contribute to lessening depressive symptoms in some patients.<p>This makes more sense if you think about other conditions like chronic pain. Someone suffering from chronic pain doesn&#x27;t have an &quot;endogenous opioid deficiency&quot;. They&#x27;re just in pain. Opioids are one medication we can use to modulate their pain.<p>Unfortunately, the pop-culture misunderstandings about &quot;low serotonin&quot; can mislead a lot of people into thinking that research like this debunks SSRIs. It doesn&#x27;t. As I said above, we&#x27;ve known for decades that something else is going on. This isn&#x27;t actually a surprise to anyone in the field.