The Effects of Kynurenine Aminotransferase Inhibition in People With Schizophrenia

ClinicalTrials.gov ID: NCT04013555

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Brief summary

Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.

Kynurenic acid (KYNA) is a naturally occurring chemical in the brain. Studies with rodents indicate that levels of KYNA can impact levels of the neurotransmitters glutamate and dopamine. One way to reliably increase KYNA levels is by ingesting the amino acid tryptophan. Tryptophan is a normal part of the human diet. Tryptophan gets metabolized/changed to other chemicals in the body- including KYNA. By giving people 6 grams of tryptophan, the investigators will be able to increase the KYNA level in a controlled way. The investigators will then be able to study the effects of KYNA on neurotransmitters by using cognitive tests and magnetic resonance imaging techniques (measuring brain activity and brain chemistry using the MRI magnet). The overall goal of the study is to examine how the medication N-acetylcysteine (NAC), when added to tryptophan, affects various cognitive functions, such as verbal and visual memory. The investigators will also use magnetic resonance imaging (MRI) to examine how NAC affects brain activity and chemicals.

Study identification

NCT ID: NCT04013555
Recruitment status: Completed
Study type: Interventional
Phase: Phase 1, Phase 2
Lead sponsor: University of Maryland, Baltimore; Other
Enrollment: 88 participants

Conditions and interventions

Conditions

Interventions

Drug

Eligibility (public fields only)

Age range: 18 Years to 55 Years
Sex: All
Healthy volunteers: Healthy volunteers not accepted

This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.

Study timeline

Start date: Jan 20, 2020 (Actual)
Primary completion: Aug 14, 2024 (Actual)
Completion: Aug 14, 2024 (Actual)
Last update posted: Feb 11, 2026

2020 – 2024

United States locations

U.S. sites: 1
U.S. states: 1
U.S. cities: 1

Facility	City	State	ZIP	Site status
Maryland Psychiatric Research Center (MPRC) ; the Treatment Research Program (TRP)	Catonsville	Maryland	21228	—

Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.

About this trial record page

What this page shows: Public field values for ClinicalTrials.gov record NCT04013555, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
What this page does not do: No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
Where the data comes from: Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
Last refresh: Last update posted Feb 11, 2026 · Synced Nov 15, 2026