Efficacy and safety of 5-hydroxytryptophan on depression and apathy in Parkinson's disease: a preliminary finding

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Efficacy and safety of 5-hydroxytryptophan on depression and apathy in Parkinson's disease: a preliminary finding

Meloni et al., 2020 | Eur J Neurol | Rct

Citation

Meloni M, Puligheddu M, ... Defazio G. Efficacy and safety of 5-hydroxytryptophan on depression and apathy in Parkinson's disease: a preliminary finding. Eur J Neurol. 2020-May;27(5):779-786. doi:10.1111/ene.14179

Abstract

BACKGROUND AND PURPOSE: Several studies have indicated that altered serotonergic neurotransmission may contribute to non-motor features commonly associated with Parkinson's disease (PD) such as apathy and depression. 5-hydroxytryptophan (5-HTP) is the intermediate metabolite of L-tryptophan in the production of serotonin. To date, there has been inconsistent research on the use of 5-HTP in PD. The purpose of this study was to compare the effects of 5-HTP with those of placebo on apathy and depressive symptoms in patients with PD. METHODS: A single-center, randomized, double-blind placebo-controlled cross-over trial was employed; 25 individuals were subsequently enrolled into the study. Patients received placebo and 50 mg of 5-HTP daily over a period of 4 weeks. For the assessment of efficacy on depressive and apathy symptoms the Beck Depression Inventory-II (BDI-II), Hamilton Depression Rating Scale (HDRS) and Apathy Scale (AS) were respectively administered at screening, baseline and weeks 4, 8, 12 and 16. Primary efficacy outcomes were the comparison of 5-HTP to placebo in mean change from baseline to weeks 4, 8, 12 and 16 in total score on the AS, BDI-II and HDRS. RESULTS: Repeated-measures analysis revealed a significant improvement of depressive symptoms during the 50-mg 5-HTP treatment compared with placebo as assessed by the HDRS. No effect of 5-HTP was seen on apathy symptoms assessed by the AS. CONCLUSIONS: This study provides preliminary evidence of clinical benefit of 5-HTP for treating depressive symptoms in PD. Larger studies with a longer treatment duration are needed to corroborate these early findings.

Key Findings

Repeated-measures analysis revealed a significant improvement of depressive symptoms during the 50-mg 5-HTP treatment compared with placebo as assessed by the HDRS. No effect of 5-HTP was seen on apathy symptoms assessed by the AS.

Outcomes Measured

  • depression

Population

Field Value
Population pd
Sample Size 25
Age Range See abstract
Condition depression

MeSH Terms

  • 5-Hydroxytryptophan
  • Aged
  • Apathy
  • Cross-Over Studies
  • Depression
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Parkinson Disease

Evidence Classification

  • Level: Rct
  • Publication Types: Journal Article, Randomized Controlled Trial
  • Vertical: 5-htp

Provenance

Source extracted via PubMed E-utilities API on 2026-04-10