Leucine for Depression Study (L-DEP)

Study Summary

Depression is very common and poses a huge disease burden. About 20% of the US population suffers from depression at lease once in their lifetime. Inflammations that are hidden inside our body as a result of aging, obesity, chronic diseases, or certain treatments (e.g., interferon for hepatitis C) appear to cause depressive symptoms and even clinical depression. Individuals with such inflammations are more likely to suffer from depression and are less likely to respond to currently available antidepressant medications. This study will test leucine, an amino acid, as a new way to mitigate depressive symptoms in response to such inflammations. This study begins with a 90-minute screening session to determine whether participants are eligible to join the main study. Those who meet the eligibility criteria will then join the main study, which will consist of taking leucine or maltodextrin (i.e., oral placebo) for 2 weeks at home and an 8-hour session at the UCLA Medical Center. A brief telephone follow-up every 3 months for 2 years with questions on mood is also planned. Approximately 90 healthy adults will be recruited for participation in the study. During the course of the study, participants will take leucine or maltodextrin for 2 weeks at home and then will be injected either lipopolysaccharide (LPS) or saline (i.e., intravenous placebo) at the UCLA Medical Center. LPS is a bacterial substance that can initiate chemical reactions that are similar to those seen in individuals with mild sickness symptoms, such as a slight increase in body temperature, muscle aches, or tiredness. It is a safe way of investigating the body's response to inflammation and how these changes may alter cognitive, emotional, or neural function. It has been given thousands of times to healthy volunteers - both younger and older adults - without any serious side effects.

Primary Outcome

Depression Subscale of the Short Form of the Profile of Mood States (POMS-SF): total score ranges from 0 to 32; higher values represent worse outcome, i.e., more severe depressed mood; the absolute values at each time point are presented here rather than change of values between time points; zero (0) in mean and standard deviation reflect measured data and not placeholder values.

Interventions

• OTHER IV placebo
• DIETARY_SUPPLEMENT leucine
• OTHER PO placebo
• BIOLOGICAL lipopolysaccharide (LPS)