Serotonin is a mood-enhancing neurotransmitter that can help prevent depression and anxiety disorders. Doctors normally prescribe antidepressants as a way of raising the brain's levels of serotonin when the levels are too low. 5-HTP is an over-the-counter serotonin supplement that may raise the brain's levels of serotonin by converting into active serotonin once it crosses over from the bloodstream to the brain. Serotonin drugs are not likely to suppress natural serotonin production.
Serotonin, Anxiety and Depression
Low levels of serotonin can give rise to increased processing in the amygdala, the brain's main fear-processing center. This in turn can lead to increased secretion of the stress hormones cortisol, adrenaline and noradrenaline. Low levels of serotonin may also affect dopamine levels, leading to a lack of motivation and a lack of interest in otherwise pleasurable activities.
Standard Treatment
Doctors normally prescribe serotonin reuptake inhibitors as a treatment for low levels of serotonin. The most commonly prescribed drugs are second-generation antidepressants, also known as selective serotonin reuptake inhibitors. These drugs block the serotonin transporter in the brain. The serotonin transporter deactivates serotonin by carrying it back into the cells. By blocking the transporter, selective serotonin reuptake inhibitors increase the brain's levels of active serotonin.
Dietary Supplement 5-HTP
The dietary supplement 5-hydroxy-L-tryptophan, or 5-HTP, is an immediate precursor to serotonin. At the time of publication, 5-HTP was not regulated by the FDA, which means you coul buy it as an over-the-counter dietary supplement. 5-HTP is preferable to serotonin as a supplement because it can cross the blood-brain barrier. Though the effects of 5-HTP have been studied only in mice, the supplement may help increase the brain's levels of serotonin in humans. As 5-HTP can have serious side effects, consult your doctor before you consider taking it.
Serotonin Suppression
There is no direct evidence suggesting that serotonin reuptake inhibitors or 5-HTP can suppress the brain's natural ability to produce serotonin. However, there are theoretical reasons to believe serotonin drugs could help correct an imbalance. The brain tends to form habits. If fear processing in the amygdala is elevated over a long time period, the amygdala grows larger, which means fear processing is more likely to occur. Likewise, a long-lasting serotonin depletion could decrease the number of serotonin receptors in the brain. By correcting a serotonin imbalance, serotonin drugs could prevent growth of the amygdala and a decrease in serotonin receptors.
References
- MayoClinic.com: Anxiety Disorders
- MayoClinic.com: Depression
- "Behavioral Brain Research"; Increases in Avoidance Responding Produced by REM Sleep Deprivation or Serotonin Depletion Are Reversed by Administration of 5-Hydroxytryptophan; R.L Smith and C.H. Kennedy; March 2003
- "Journal of Psychiatry and Neuroscience"; How to Increase Serotonin in the Human Brain Without Drugs; Simon N. Young; November 2007
- "Scientific American"; Emotion, Memory and the Brain; Joseph E. LeDoux; June 1994
- "Psychological Medicine"; Enlarged Amygdala Volume and Reduced Hippocampal Volume in Young Women With Major Depression; C. Lange and E. Irle; August 2004
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