5-hydroxytryptophan is a compound synthesized within the body and used as the precursor chemical for the production of serotonin. As one of the most important neurotransmitters in the nervous system, serotonin's activity has been linked in a number of scientific studies to the development of the neurological condition schizophrenia. More research is needed, however, to determine if it is 5-hydroxytryptophan and serotonin levels or instead their effect on other neurotransmitter levels that may contribute to schizophrenia.
5-Hydroxytryptophan
5-hydroxytryptophan, also known as 5-HTP, is synthesized from the amino acid tryptophan, which is found in high concentrations in foods like milk, chicken, turkey, collard greens, pumpkin, potatoes, seaweed and sunflower seeds. 5-hydroxytryptophan is also available in dietary supplements of extracts from the African Griffonia simplicfolia tree's seeds -- though, because of the lack of FDA oversight for supplements, you should speak to your physician before using any 5-HTP supplements. 5-hydroxytryptophan has one major role in the body: it is used to produce serotonin. Serotonin is essential in the regulation of behavior and mood. Because of its role in serotonin production, 5-hydroxytryptophan has been studied as a treatment for depression, insomnia and some fibromyalgia symptoms, though more research is needed before its use for these conditions can be approved.
Effect on Schizophrenia
Research studies indicate that serotonin levels in the brain may directly exacerbate schizophrenia symptoms. Schizophrenia may be connected to a hypersensitivity of the neurons' synaptic serotonin receptors. Since the levels of available serotonin are connected to the levels of available 5-hydroxytryptophan, some researchers suggest that a possible treatment of schizophrenia might include medications that block either serotonin or 5-hydroxytryptophan. A review article in the "Schizophrenia Bulletin," however, advises that serotonin's role in schizophrenia is still far from fully understood.
Interaction With Dopamine
A large body of scientific evidence indicates that another neurotransmitter, dopamine, may also play a major role in schizophrenia. Like serotonin, some studies indicate that increased levels of dopamine and a hyperactive sensitivity of dopamine receptors in the brain may be an abnormality that leads to schizophrenia. Additionally, researchers report that increased levels and sensitivity to serotonin may directly cause a hypersensitivity to dopamine, possibly increasing the risk of developing schizophrenia. One of the best proofs for a possible link between schizophrenia and a relationship between serotonin and dopamine is that clozapine, a highly effective schizophrenia medication, works by blocking receptors for both neurotransmitters. However, according to an article in "Current Drug Therapy," there is still a good deal of dispute among scientists about whether dopamine levels or a dopamine-serotonin interaction causes schizophrenia.
Expert Insight
Much more research is needed before any chemical -- whether 5-hydroxytryptophan, serotonin or dopamine -- can be definitively linked with schizophrenia, yielding a possible avenue for treatment. It is difficult for scientists to connect any of these compounds with schizophrenia development since, as of 2011, there is no way to know if the results of current studies reflect causal or secondary relationships or if they are a result of the environment or unrelated biological mechanisms.
References
- University of Maryland Medical Center: 5-Hydroxytryptophan (5-HTP)
- "Schizophrenia Bulletin"; The Role of Serotonin in Schizophrenia; Avraham Bleich, et al.; 1988
- MayoClinic.com: Schizophrenia
- Biology Online: The Neurotransmitter Hypothesis of Schizophrenia
- "Current Drug Therapy"; Pharmacotherapy of Schizphrenia: The Past, Present and Future; Shahin Akhondzadeh; 2006
- Brain Explorer: Schizophrenia
