Back in the '50s and '60s with the discovery of LSD and subsequently serotonin, there began an interest in finding endogenous hallucinogenic compounds that may be responsible for mental illness. In the late 1960's and through the 1970's they hit upon DMT, 5-MeO-DMT, and bufotenine as promising candidates for these "schizotoxins" and there are several studies measuring the levels of these compounds in urine, blood, and even spinal fluid of mentally ill patients. Little came of this research and the endogenous schizotoxins theory fell out of favor as research progressed and our understanding of the complexity of mental illness grew.
However, there have been a few more recent follow up studies that are quite intriuging.
Takeda, N., Ikeda, R., Ohba, K., & Kondo, M. (1995). Bufotenine reconsidered as a diagnostic indicator of psychiatric disorders. Neuroreport, 6(17), 2378-2380.
https://europepmc.org/article/med/8747157Emanuele, E., Colombo, R., Martinelli, V., Brondino, N., Marini, M., Boso, M., ... & Politi, P. (2010). Elevated urine levels of bufotenine in patients with autistic spectrum disorders and schizophrenia. Neuroendocrinol Lett, 31(1), 117-121.
https://d1wqtxts1xzle7.c...xp53bqNt3kmRoZ38Xj8dORyZ~vzFBvxPn0E-yEgS2SDibHLvMdSCVnLLmF957hlEwsnKvAVIOO9PsyIrESPW~DXCunpcNgcOp-RxyVmccsfIP9xkkPfytEWTgIupLyDWo3bStilJyM6FRzgme~v27tt47sHoFAbjSDjfIwuujvugBq1CIUZULBSoIE8ox-nQvBs5LUPj0dAuU7op647Mf-~DJlNRDJVT~qxX37UXRipZAR~MLXzu4-SF6Tu-enR6FA6v1OizUbGj5~hpE2uMzAYtEGadQ__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA
Shomrat, T., & Nesher, N. (2019). Updated view on the relation of the pineal gland to autism spectrum disorders. Front Endocrinol (Lausanne). 2019; 10: 37.
https://www.frontiersin....89/fendo.2019.00037/full