Table 2.

Correlation between the Hamilton Depression Rating Scale (HAM-D) score and levels of tryptophan (TRP) and its metabolites in urine of elderly individuals with mood disorders. The correlations were analyzed using the Spearman rank test.

Pair of Variables a	Spearman’s ρ	p
HAM-D and TRP	−0.574738	<0.001
HAM-D and 5-HIAA	−0.450369	<0.001
HAM-D and KYN	0.537382	<0.001
HAM-D and KYNA	−0.229663	<0.05
HAM-D and QA	0.739648	<0.001
HAM-D and KYNA/KYN	−0.484408	<0.001
HAM-D and KYNA/QA	−0.540872	<0.001

^a 5-HIAA—5-hydroxyindoleacetic acid, KYN—kynurenine, KYNA—kynurenic acid, QA—quinolinic acid; n = 40, ρ—Spearman’s rank correlation coefficient.