Urinary serotonin may be key to test for depression

It's winter here in the northern hemisphere, the days are short and moods are low. For some people, even the thought of Christmas isn't enough to lift their mood. Depression can affect up to two out of every three adults at some point in their lives, and it can go undiagnosed. NeuroScience, a company specializing in laboratory testing, is developing a urinary serotonin test that it believes could be a noninvasive test for depression.

Serotonin is a neurotransmitter--it relays messages in the brain--and has been linked with depression. Theories as to this link include low levels of serotonin, low numbers of receptors, or issues with the serotonin reaching the receptors. While their mode of action isn't completely understood, a number of antidepressants, such as the SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin and norepinephrine reuptake inhibitors) increase the levels of serotonin in the brain.

The research, published in Analytical and Bioanalytical Biochemistry, used ELISA (enzyme-linked immunosorbent assay--a biochemistry assay that uses enzymes to assess levels of substances) to measure levels of serotonin in urine. The test, which was validated against other established assays, showed that serotonin levels were lower in depressed than in nondepressed subjects, and increased after treatment with 5-hydroxytryptophan (5-HTP), a substance that the body converts into serotonin or SSRIs. This analytical test could be useful in developing therapeutics in which the mechanism of action is based on changes in serotonin levels.

Depression isn't always easy to diagnose, and different people can have wildly different symptoms, from low mood and problems sleeping to aching and pain. Having a biomarker could make diagnosis more objective. However, the links between serotonin levels and depression are still not clear, and so more research is needed before tests like this can be used in depression screening.

- read the release
- check out the abstract