How long does it take for antidepressant drugs to work?

If you have depression, you should take medication in time to control the disease and gradually improve the patient's condition. When taking antidepressant drugs, it usually takes 6 to 8 weeks to maintain an effective dose, which can stabilize the condition. Then you can gradually reduce the dosage under the guidance of a doctor. In addition, it is also important for patients to find antidepressants that work quickly.

Neurochemical theory

The time lag between the onset of pharmacological and therapeutic effects of antidepressants is often measured in weeks, leading researchers to attempt to explore the neuroadaptive changes that occur during this time. One potential explanation for the delayed onset of antidepressant effects is that simply blocking the reuptake of 5-HT and NE can only exert an indirect effect, while the neurobiological adaptive changes brought about by repeated administration have a more direct antidepressant value.

Searching for a fast-acting antidepressant

Compared to antidepressants that have a delayed onset of action, studies have shown that a single dose of ketamine can rapidly improve depressive symptoms and suicidal thoughts within hours. It is noteworthy that these studies also included patients who had an inadequate response to two or more conventional antidepressants (such as SSRIs and SNRIs).

Ketamine induces an abnormal increase in extracellular glutamate levels in the medial prefrontal cortex, and its behavioral effects can be blocked by pre-administered glutamate receptor antagonists, suggesting that ketamine may induce activity-dependent release of BDNF and rapid synaptogenic effects. Others believe that ketamine enhances synaptic function through a homeostatic mechanism by blocking NMDA receptors on postsynaptic principal neurons. Relevant research is still ongoing.

Neuroplasticity theory

With the elucidation of the molecular and cellular pathways that regulate neuronal function, researchers have gone beyond the level of monoamine neurotransmitter receptors when exploring the mechanism of action of antidepressants and have focused their attention on intracellular signaling cascades, gene expression, and protein translation. Among them, the mechanism of neuroplasticity has become an important topic. Neuroplasticity is related to processes such as learning and memory, and also reflects the ability of the nervous system to effectively cooperate, adapt to environmental stimuli, and respond appropriately to related stimuli in the future.

Evidence shows that chronic stress can affect synaptic plasticity: at the molecular level, chronic stress can lead to changes in glutamate, intracellular signals,