Functional Evaluation in Patients With Urea Cycle Disorders (UCD) During a Driving Task

July 29, 2026 updated by: St. Jude Children's Research Hospital

Cognitive and Motor Function Examination in Patients With Urea Cycle Disorders (UCD) During a Driving Task Using Functional Near Infrared Spectroscopy (fNIRS)

This study is being done to understand how the brain works while people with urea cycle disorder (UCD) perform driving tasks that range from easy to difficult and to look at how that compares to traditional tests of thinking and attention.

Study Overview

Status

Recruiting

Conditions

Urea Cycle Disorder

Detailed Description

Primary Objective

To use fNIRS to study brain functional behavior in subjects with UCD by measuring the changes in HbO, HbR and HbT concentrations versus healthy control volunteers during the baseline driving task on the left and right prefrontal cortex (LPFC, RPFC).

Secondary Objective

To include other cortical regions such as temporal and occipital regions, to investigate the neurocognitive changes in these regions which may or may not change with driving. Thus, we will measure changes in HbO, HbR and HbT concentrations during the baseline driving task in four more brain regions (left and right parietal and occipital regions, LPA, RPA, LOL, ROL).

This is a non-therapeutic, non-interventional study in which brain fNIRS (functional near-infrared spectroscopy) measures will be compared under simulated driving conditions between patients with UCD vs. age and sex-matched control participants.

Participants who agree to participate will have Information about their medical history collected, have a basic neurological exam and answer questions about their health, diet, and driving habits. They will complete some simple thinking and memory tests. These tests will help investigators understand skills like memory, attention, and problem-solving. Participants will also wear a soft cap with small sensors called an fNIRS (functional near-infrared spectroscopy) device while they complete a driving simulator activity. This cap is noninvasive and measures how the brain uses oxygen while they drive in the simulator.

All study activities will be completed on the day of enrollment.

Study Type

Observational

Enrollment (Estimated)

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Name: Jean Laboe, RN
Phone Number: 901-595-1693
Email: jean.laboe@stjude.org

Study Locations

United States
- Tennessee
  - Memphis, Tennessee, United States, 38105
    - Recruiting
    - St. Jude Children's Research Hospital
    - Contact:
      
      Jean Laboe, RN
      
      Phone Number: 901-595-1693
      
      Email: jean.laboe@stjude.org

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

Child
Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Individuals who meet the Eligibility Criteria and agree to participate.

Description

Inclusion Criteria:

Individuals 16 to 40 years with molecular or biochemical confirmation of a urea cycle disorder.
Healthy individuals will serve as an age and sex matched comparison group. Active driver's license for at least 6 months
Read and understand English. as the tasks have not been validated in other languages
IQ >=70.

Exclusion Criteria:

Skin disease that affects the scalp
Past or present vascular disease
Head trauma with loss of consciousness in the last year or evidence of cognitive impairment due to and persisting after head trauma
Motor movement disorder which may cause excessive movement or impede use of the steering wheel and/or pedal
Premature birth or birth before 32 weeks of gestation
The participant is taking a stimulant or antidepressant
Allergy to any component of the device, although expected to be rare
History of psychosis
Self-reported motion or cyber sickness
Self-reported illicit substance use
Vision disorder

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Number of groups / cohorts

Cohorts and Interventions

Group / Cohort
UCD group Participants with urea cycle disorders (UCD) who meet the Eligibility Criteria and consent to participate
Control group Healthy controls who meet the Eligibility Criteria and consent to participate

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Oxyhemoglobin (HbO), Deoxyhemoglobin (HbR) and Total Hemoglobin (HbT) concentrations in the right and left prefrontal cortex in participants with urea cycle disorders (UCD) compared to healthy control volunteers Time Frame: Day 1, during driving simulator task	Investigators will compare prefrontal cortex hemoglobin concentrations during low cognitive load between patients with UCD and healthy age and sex matched control participants using functional near-infrared spectroscopy (fNIRS). Mean values of hemoglobin concentration differences on the right and left prefrontal cortex between individuals, with and without UCD, during the low cognitive load task will be calculated and compared using two sample t-tests (for normally distributed data) or Wilcoxon rank sum tests (for nonnormally distributed data). P values will be adjusted for multiple comparisons using the Bonferroni method.	Day 1, during driving simulator task

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in HbO, HbR and HbT concentrations in the left and right parietal and occipital brain regions in participants with urea cycle disorders (UCD) compared to healthy control volunteers Time Frame: Day 1, during driving simulator task	Investigators will compare left and right parietal and occipital regions hemoglobin concentrations during low cognitive load between patients with UCD and healthy age and sex matched control participants using functional near-infrared spectroscopy (fNIRS). Mean values of hemoglobin concentration differences on the left and right parietal and occipital regions between individuals, with and without UCD, during the low cognitive load task will be calculated and compared using two sample t-tests (for normally distributed data) or Wilcoxon rank sum tests (for nonnormally distributed data). P values will be adjusted for multiple comparisons using the Bonferroni method.	Day 1, during driving simulator task

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

St. Jude Children's Research Hospital

Investigators

Principal Investigator: Andrea Gropman, M.D., St. Jude Children's Research Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 20, 2026

Primary Completion (Estimated)

August 1, 2031

Study Completion (Estimated)

August 1, 2032

Study Registration Dates

First Submitted

July 8, 2026

First Submitted That Met QC Criteria