Indoleamine metabolites in the cerebrospinal fluid of depressed patients before and during treatment with nortriptyline

Abstract

Cerebrospinal fluid (CSF) levels of the indoleamine metabolites, 5‐hydroxyindole‐3‐acetic acid (5‐HIAA) and indole‐3‐acetic acid (IAA) were measured by a specific mass fragmentographic method in 43 depressed psychiatric in‐patients. The mean level of 5‐HIAA was 19.7 ± 7.9 ng per milliliter. The 5‐HIAA concentration was positively correlated to age, and there was a tendency for women to have higher values than men. The distribution of 5‐HIAA concentrations appeared to be bimodal in the 27 patients with a depression of endogenous type. The bimodality could not be explained by differences in age or sex. The mean level of IAA was 6.4 ± 4.1 ng per milliliter. The distribution of IAA was unimodal. The correlation to age was not significant, and there was no sex difference. There was a positive correlation between the concentrations of the two metabolites. Twenty patients were treated with nortriptyline, 50 mg three times daily by mouth. After three weeks treatment, the concentrations of 5‐HIAA and IAA had decreased significantly. The mean decrease was 4.8 and 2.0 ng per milliliter, respectively. The magnitude of the decrease was not cormlated to the plasma level of nortriptyline. The data suggest that endogenous depression is a hiochemically heterogenous disease. There may be a subgroup of patients within the endogenous syndrome where indoleamine metabolism is disturbed. In these patients, treatment with drugs that influence indoleamines more directly than a typical noradrenaline uptake inhibitor like nortriptyline, may lead to better therapeutic results.