This isn’t “news”, but I thought, given I’ve been talking about Blood Brain Barrier permeability a bit lately and there is some discussion circulating concerning the relevance of neurotransmitter function in mental health, it might be worth bringing this following study to light:
This is just the relevant part of the outcome:
Conclusion
The “spot baseline urinary neurotransmitter testing marketing model” used
to promote sales of urinary monoamine assays is not valid and has no
scientific foundation. For the claims of the marketing model to be
valid, monoamines would need to cross the blood–brain barrier and be in
constant equilibrium with the peripheral nervous system and final urine.
As demonstrated by at least 100 citations, these monoamines do not
cross the blood–brain barrier. While one version of the marketing model
seems to recognize this and asserts that the monoamines are transported
out of the central nervous system, the very literature cited in making
these transporter assertions specifically illustrates that monoamines
are not transported out of the central nervous system to the peripheral
nervous system. For the marketing model to be valid, monoamines found in
the final urine need to be composed primarily of the monoamines from
the peripheral system that are merely filtered and placed in the final
urine as claimed. A significant amount of monoamines found in the final
urine are synthesized by the kidneys. These monoamines perform other
major functions in the body. Therefore, identifying and calling these
monoamine assays of the final urine, “neurotransmitter testing” is not
appropriate.
Save your money, folks.