Selective serotonin reuptake inhibitors, or SSRIs, relieve depression and other psychological ailments by balancing levels of the neurotransmitter serotonin within the brain, according to WebMD. SSRIs decrease the reabsorption of serotonin into the neurons of the brain, which in turn effectively treats depressive and anxious symptoms, states the National Institutes of Health.
Serotonin is a chemical in the brain known as a neurotransmitter, according to Wikipedia. The imbalance of serotonin related to depression and anxiety is caused by excess quantities of serotonin leaving the synapses, which are the spaces between neurons within the brain, and re-entering the neurons. By inhibiting the reuptake of serotonin into neurons, SSRIs effectively correct the levels of serotonin within the synapses and regulate its transmission into the neurons. Scientific studies show that this process relieves depression and anxiety in some test subjects. Other antidepressants, such as tricyclic antidepressants, momoamine oxidase inhibitors and serotonin norepinephrine reuptake inhibitors, also work by regulating serotonin and other neurotransmitter levels.
Inadequate levels of serotonin within the synapses are believed to cause depression because serotonin is necessary to the process of electrical signals being transmitted between neurons. To properly regulate mood, the neurons in the brain must be interconnected and allow electrical impulse transmission between them, states the National Institutes of Health.