Dr. Andrew Weil, M.D., says that depression is the most common and the most treatable form of mental illness. Depression is a feeling of loss that is not triggered by an external cause or is out of proportion to the cause. It is often accompanied by tiredness and fatigue. Other symptoms may include feelings of hopelessness, anxiety and a sullen mood. Sleep may be affected as well as appetite. Fortunately, many medications help with depression.
Selective Serotonin Reuptake Inhibitors
The book "Pharmacology" explains that a reuptake inhibitor is a substance that slows the reabsorption of a chemical. In the case of newer antidepressant medications, the reuptake inhibitors slow the reabsorption of chemicals that make you feel good, allowing them to work longer. Selective serotonin reuptake inhibitors slow the reabsorption of serotonin. Serotonin is found throughout the body, but its job in the brain includes regulating mood, sleep and appetite. A shortage of serotonin causes depression and anxiety. One way to increase the amount of serotonin in the brain is by using SSRIs to slow its reabsorption.
Serotonin and Norepinephrine Reuptake Inhibitors
The Mayo Clinic reports that serotonin and norepinephrine reuptake inhibitors, or SNRIs, are similar to SSRIs except they also slow the reabsorption of norepinephrine. Norepinephrine is a neurotransmitter, a substance that the brain uses for communication. It is a substance that makes you feel good. Just like SSRIs, SNRIs slow the reabsorption of serotonin as well as norepinephrine, which has the effect of increasing the amount of these chemicals in the brain. The overall effect is that depression is decreased and you feel better.
Norepinephrine and Dopamine Reuptake Inhibitors
The Mayo Clinic goes on to explain that norepinephrine and dopamine reuptake inhibitors, or NDRIs, inhibit the reabsorption of dopamine as well as norepinephrine. Dopamine is another "feel good" neurotransmitter. Low levels of dopamine are related to depression and schizophrenia.
Tricyclic Antidepressants
Tricyclic antidepressants are older antidepressants that work well but have more severe side effects than the newer formulations. The book "Pharmacology" states that tricyclic antidepressants indiscriminately block reabsorption of several neurotransmitters including serotonin and norepinephrine. The overall effect is an elevation of mood, more mental alertness and increased activity.
Monoamine Oxidase Inhibitors
According to the Mayo Clinic, monoamine oxidase inhibitors, or MAOIs, have serious side effects and are considered a drug of last resort. Monoamine oxidase is a chemical found in nerve cells. Its job is to deactivate excess neurotransmitters, including serotonin, dopamine and norepinephrine. MAOIs inactivate the monoamine oxidase, which allows the neurotransmitters to work longer and make a person feel less depressed.
References
- Weil: Natural Depression Treatment
- "Pharmacology," Second Edition; Mary Mycek, Richard Harvey, Pamela Champe; 2000
- Mayo Clinic: Depression (Major Depression)
