Some patients with depression have decreased levels of the blood molecule acetyl-L-carnitine, according to a study published in Proceedings of the National Academy of Sciences. Screening blood for acetyl-L-carnitine could help improve the process of diagnosing major depressive disorder. The discovery could also lead to better treatment options for patients with major depressive disorder.
Depression is a common mood disorder, and it is the leading cause of disability worldwide, according to the World Health Organization.
"It's the number one reason for absenteeism at work," says Natalie Rasgon, a doctor and professor of psychiatry and behavioral sciences at Stanford University, in an interview with the Stanford Medicine News Center.
Acetyl-L-carnitine is a blood molecule that the body produces naturally. It is involved in regulating energy and it influences the gene that controls glutamate, which is a chemical that is involved in brain function.
The study compared the levels of acetyl-L-carnitine in people diagnosed with major depressive disorder with the levels in people without this diagnosis. They found that the levels of acetyl-L-carnitine were significantly lower in patients with major depressive disorder.
The levels of acetyl-L-carnitine were even lower in patients who had treatment-resistant depression.
"In patients with depression, something is causing a problem in the mechanisms related to the biology of acetyl-L-carnitine. And, surprisingly, the deficiency in acetyl-L-carnitine is even stronger in patients that don't respond to standard antidepressants," says Carla Nasca, a Rockefeller University scientist involved in the study.
Screening for acetyl-L-carnitine could help doctors diagnose depression. In particular, it could help diagnose severe depression that is resistant to treatment and may stem from childhood trauma. The study found that acetyl-L-carnitine levels were even lower in patients who had experienced childhood trauma. Those lower levels were particularly noticeable in women.
Having a better understanding of the relationship between acetyl-L-carnitine and its relationship to brain function could lead to improved treatment.
Previous studies done by Nasca and her colleague Bruce McEwen have shown that supplementing acetyl-L-carnitine in mice with depression improved their symptoms.
The study did not test if taking acetyl-L-carnitine supplements improved the treatment of depression, though.
"We are at the very beginning of this discovery and can't recommend people to buy this supplement at the GNC store," Rasgon said, according to ABC News.
The authors of the study hope that their results will lead to further exploration of acetyl-L-carnitine as a treatment option, though.
"There are many questions to be answered," said Rasgon. "It is one of the pieces of a very large puzzle."