Predictive value of amino acids in the treatment of major depression with fluvoxamine

Sixteen outpatients (mean age ± SD 50.18 ± 11.55 years; 11 females and 5 males) affected by major depression without melancholia (DSM-IV) were included in the study. The control group consisted of 11 healthy volunteers (mean age ± SD 39.90 ± 13.39 years; 2 females and 9 males). Patients were treated with fluvoxamine (FVX) 100-300 mg daily. Clinical assessment was performed using the Hamilton Rating Scales for Anxiety and Depression (HRS-A; HRS-D) and the Clinical Global Impression Scale (CGI) at basal time (T₀), after 4 weeks and after 8 weeks (T₈). Plasma and platelet amino acid levels were determined at T₀ in all the subjects and also at T₈ in depressed patients. A significant clinical improvement was observed in depressed patients according to the HRS-A (p = 0.004), HRS-D (p = 0.008) and CGI (p = 0.002). A negative correlation (r = -0.53, p = 0.049) was found between platelet levels of valine and HRS-D improvement rate. Patients showed significantly higher tyrosine/large neutral amino acids (LNAAs) and lower tryptophan/LNAAs, ratios which could represent an index of good response to a serotonergic drug like FVX.