Tryptophan metabolites and medium- and long-chain fatty acids are altered in patients with major depressive disorder and schizophrenia, a new study published in Medicina found. These findings provide more understanding of dysfunctional tryptophan and fatty acid metabolism.
It is already known that the disruption of tryptophan and fatty acid metabolism, as is seen in long chain fatty acid oxidation disorder (LCFAOD), is involved in the pathogenesis of psychiatric disorders. However, only a few studies have quantified and compared tryptophan metabolites and medium- and long-chain fatty acids in patients with psychiatric disorders such as major depressive disorder and schizophrenia.
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Here, a team of researchers from China analyzed clinical symptoms and plasma levels of tryptophan and its metabolites, medium-chain fatty acids, and long-chain fatty acids in 24 patients with major depressive disorder, 22 patients with schizophrenia, and 23 healthy volunteers.
The results showed that the levels of tryptophan and its metabolites including N-formyl-kynurenine, 5-hydroxyindole-3-acetic acid, and indole were reduced in the plasma of patients with psychiatric disorders compared to those in healthy people. The levels of omega-3 polyunsaturated fatty acids (N3) and the ratio of N3 to omega-6 polyunsaturated fatty acids were also reduced in the plasma of patients with psychiatric disorders.
Moreover, the levels of saturated and monounsaturated fatty acids were lower in the plasma of patients with schizophrenia.
There was also a significant difference in the composition of medium- and long-chain fatty acids between people with major depressive disorder and those with schizophrenia.
Finally, the top 10 differential molecules could help distinguish patients with a psychiatric disorder from healthy people as well as patients with major depressive disorder from those with schizophrenia.
These findings could not only help researchers develop “combinatorial classifiers” to distinguish between psychiatric disorders, but they also highlight a possible link between LCFAOD and psychiatric disorders.
LCFAOD is a group of genetic diseases characterized by the accumulation of long-chain fatty acids in the body due to the deficiency of enzymes that are crucial for their metabolism.
Reference
Liu JC, Yu H, Li R, et al. A preliminary comparison of plasma tryptophan metabolites and medium- and long-chain fatty acids in adult patients with major depressive disorder and schizophrenia. Medicina (Kaunas). Published online February 20, 2023. doi:10.3390/medicina59020413
