Individuals with severe depression may have low blood levels of an amino acid involved in brain function called acetyl-L-carnitine (LAC). In this study, researchers found that participants with depression have lower serum levels of LAC than those without a history of depression and that patients with more severe depression had even lower LAC levels. The research team also observed a link between lower LAC levels and both depression that starts earlier in life and depression that is treatment-resistant.
Proceedings of the National Academy of Sciences, July 2018