Autism Spectrum DisorderASDNCT02733120
Metabolic Processes in Adults and Adolescents With Autism Spectrum Disorder
A study testing stable isotope infusion in people with Autism Spectrum Disorder, run by Texas A&M University at 1 site in United States.
Trial summary
The objective of this study is to gain preliminary information and knowledge on metabolic profile in ASD. The benefit of this study will be to expand our insight of the potential relationship in metabolic processes and neuropsychological functions in ASD. Read more about this study
- Who is it for?
- Ages 16 years and olderHealthy volunteers can take part
- Conditions the study is for
- Autism Spectrum Disorder
- What is being tested?
- stable isotope infusion
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 3 Dec 2015to 30 Oct 2017
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 years and older
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- Healthy male or female according to the investigator's or appointed staff's judgment
- Age 16 years or older
- Ability to walk, sit down and stand up independently
- Ability to lie in supine or elevated position for 4 hours
- Willingness and ability to comply with the protocol
- Inclusion criteria subjects with Autism Spectrum Disorder (ASD):
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- Healthy high functioning person diagnosed with autism spectrum disorder
- Age 16 years or older
- Ability to walk, sit down and stand up independently
- Ability to lie in supine or elevated position for 4 hours
- Willingness and ability to comply with the protocol
Who cannot join
- Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (for healthy group)
- Failure to give informed consent
- Established diagnosis of Insulin Dependent Diabetes Mellitus
- Metabolic diseases, including hepatic or renal disorders
- Presence of acute illness or metabolically unstable chronic illness
- Presence of fever within the last 3 days
Show all 13Show fewer
- Pre-planned surgery of procedures that would interfere with the conduct of the study
- Any other condition according to the PI or study physician that would interfere with proper conduct of the study / safety of the patient
- Current alcohol or drug abuse
- Use of protein or amino acid containing nutritional supplements within 5 days prior to the study days
- Use of long-term oral corticosteroids or short course of oral cortico-steroids 4 weeks preceding first test day
- Body Mass Index of < 18.5 or ≥ 40 kg/m2
- Montreal Cognitive Assessment score of < 20
Trial locations and contacts
1 site in 1 country.
United States1 site
Texas A&M University-CTRAL
College Station, Texas, 77843
About this study
Official title: Study on Metabolic Processes and Cognitive Functions in Adults and Adolescents With Autism Spectrum Disorder
The objective of this study is to gain preliminary information and knowledge on metabolic profile in ASD. The benefit of this study will be to expand our insight of the potential relationship in metabolic processes and neuropsychological functions in ASD. For example, based on the obtained data of the study we can determine whether there is a link between the tryptophan pathway and cognitive functions in autism. The project is based on a systematic and multidisciplinary approach using tracers for delineating the mechanism by which the metabolism of amino acids like TRP is involved in affective and cognitive functions in ASD. Using an innovative approach to the evaluation of amino acids has not been used in adults with ASD. In addition, the obtained data of the study holds promise to develop specific markers (metabolic and/or neuropsychological) for guiding the identification those individuals with increased risk of developing mood disturbances or cognitive impairment, and for predicting the therapeutic effect of a specific nutritional interventions in subjects with ASD.
Read the detailed description
This study investigates the metabolic profile of different amino acids and cognitive functions in adults and adolescents with ASD in comparison with age- and gender-matched healthy young adults. The study involves 1 screening visit of approximately 2 hours and 1 study day of 5 hours
The objective is to explore changes in amino acids (e.g. TRP pathway) in ASD and evaluate the function of TRP in neuropsychological functions by using the technique of stable isotope and our newly developed 'single pulse method' with multiple amino acid and keto-acid isotopes.
The aim of this study is to determine the underlying mechanism by which the metabolism of amino acids such as TRP are involved in mood and cognitive functions in ADS.
- Conditions
- Autism Spectrum Disorder
- Being tested
- stable isotope infusion
- Medical subject headings
- Autism Spectrum Disorder
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
stable isotope infusionOther
stable isotopes such as 15N2, TRP, 2H3-Leucine, L-[2H3]-3-Methylhistidine, 2H2-Glycine, 2-D-hydroxyproline, 1-13C-ketoisocaproic acid (KIC), L-[Guanido-15N2]-Arginine, L-[ureido-13C-2H2]-Citrulline), L-Glutamine-amide-15N, 1,2-13C2-L-Glutamic acid, 1,2-13C2Taurine, and 13C-Urea is given IV simultaneously
| Study group | Role | What they receive |
|---|---|---|
| Healthy matched controls | Experimental | Study Day: The subject will arrive fasted. A catheter will be inserted in the arm for stable isotope infusion and blood sampling. The hand of the arm used for blood sampling will be placed in a thermostatically controlled warmed box that heats the air. Immediately after a baseline blood sample is taken, an infusion with stable isotopes will be administered by the research nurse. Stable isotopes are given to measure amino acid metabolism. Blood samples will be collected before and/or after infusion. Subjects will be asked to complete a list of questions regarding quality of life, mood and depression, diet. Receives: Other: stable isotope infusion |
| Adults with Autism Spectrum Disorder | Experimental | The subject will arrive fasted. A catheter will be inserted in the arm for stable isotope infusion and blood sampling. The hand of the arm used for blood sampling will be placed in a thermostatically controlled warmed box that heats the air. Immediately after a baseline blood sample is taken, an infusion with stable isotopes will be administered by the research nurse. Stable isotopes are given to measure amino acid metabolism. Blood samples will be collected before and/or after infusion. Subjects will be asked to complete a list of questions regarding quality of life, mood and depression, diet. Receives: Other: stable isotope infusion |
What is being measured
The primary outcome is the main question the study is designed to answer.
Tryptophan turnover
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
Secondary outcomes (17)
leucine turnover
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
Whole body myofibrillar protein breakdown rate (reflecting muscle protein breakdown)
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
glutathione turnover
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
hydroxyproline breakdown (reflecting collagen breakdown)
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
glutamate turnover
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
taurine turnover
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
urea production
Measured: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
Group differences in state of mood as measured by the Hospital Anxiety and Depression Scale (HADS),
a fourteen item self-assessment scale. Seven of the items related to anxiety and seven relate to depression. Each item on the questionnaire is scored from 0-3 and this means that a person can score between 0 (no symptoms) and 21 (severe symptoms) for either anxiety or depression.
Measured: 1 day
Group differences in learning and memory as measured by Auditory Verbal Learning Test (AVLT)
Auditory Verbal Learning Test (AVLT): a verbal episodic memory test that evaluates a wide diversity of functions: short-term auditory-verbal memory, rate of learning, retention and recognition of information.
Measured: 1 day
Group differences in learning and memory as measured by Controlled Oral Word Association Test (COWAT),
ontrolled Oral Word Association Test (COWAT): The examinee is required to say as many words as they can think of in one minute that begin with a given letter of the alphabet. The task contains three trials. Measures phonetic verbal fluency. The raw score (total and mean words recorded across the three trials) was reported.
Measured: 1 day
Group differences in learning and memory as measured by Digit Span
recall of numbers in the same order (Digit Forward) and in reverse order (Digit Backward). Measures auditory attention and verbal working memory.
Measured: 1 day
Group differences in overall cognitive abilities as measured by Montreal Cognitive Assessment (MoCA)
assesses several cognitive domains and is used for the screening of mild cognitive impairment. Total scores range from 0-30 with lower scores indicating decreased functioning.
Measured: 1 day
Group differences in attention and executive functions as measured by Trail Making Test (TMT),
In Part A, the examinee is instructed to connect a set of 25 circles with numbers as quickly as possible while maintaining accuracy. In Part B, the examinee is instructed to connect a set of 25 circles, alternating between numbers and letters, as quickly as possible while maintaining accuracy. Measures attentional resources and is a measure of the frontal lobe "executive" functions of visual search, set-switching and mental flexibility. The total time in seconds was reported for each measure.
Measured: 1 day
Group differences in attention and executive functions as measured by Stroop Color-Word Test (SCWT),
a word page with words printed in black ink, a color page with blocks printed in color, and a color-word page where the color and the word do not match. The examinee reads the words or names the ink colors as quickly as possible within a time limit. Measures selective attention and inhibitory control. The total time in seconds was reported for each trial.
Measured: 1 day
Adolescent/Adult Sensory Profile
a standardized self-questionnaire that generates an individualized profile of sensory processing across four quadrants: low registration, sensation seeking, sensory sensitivity, and sensation avoiding.
Measured: 1 day
Group differences in attention and executive functions as measured by Brief-A
a standardized self-report that captures views of an adult's executive functions or self-regulation in his or her everyday environment.
Measured: 1 day
Group differences in attention and executive functions as measured by PASAT
a measure of cognitive function that assesses auditory information processing speed and flexibility, as well as calculation ability.
Measured: 1 day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Apr 2016 (estimated)
- Study start3 Dec 2015
- Primary completion30 Oct 2017
- Study completion30 Oct 2017
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Autism Spectrum DisorderStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Supportive care
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 40 participants (actual)
Sponsor and investigators
- Lead sponsor
- Texas A&M University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Marielle PKJ Engelen, PhD, Texas A&M University
- Investigators
- Marielle Engelen, PhD, Principal investigator, Texas A&M University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT02733120
- Sponsor's protocol ID
- 2015-0542
- Acronym
- ASD
- Status last verified
- Sep 2025
- First submitted
- 1 Feb 2016
- Last updated
- 30 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
Publications
Wierzchowska-McNew RA, Engelen MPKJ, Thaden JJ, Ten Have GAM, Deutz NEP. Obesity- and sex-related metabolism of arginine and nitric oxide in adults. Am J Clin Nutr. 2022 Dec 19;116(6):1610-1620. doi: 10.1093/ajcn/nqac277.
PubMed 36166849
Study at a glance
From the registry record, last updated by the sponsor on 30 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Study on Metabolic Processes and Cognitive Functions in Adults and Adolescents With Autism Spectrum Disorder
- ClinicalTrials.gov ID
- NCT02733120
- Acronym / sponsor ID
- ASD / 2015-0542
- Conditions
- Autism Spectrum Disorder
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 40 participants (actual)
- Lead sponsor
- Texas A&M UniversityUniversity, hospital or other
- Study start
- 3 Dec 2015 (actual)
- Primary completion
- 30 Oct 2017 (actual)
- Study completion
- 30 Oct 2017 (actual)
- First posted
- 11 Apr 2016 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The objective of this study is to gain preliminary information and knowledge on metabolic profile in ASD. The benefit of this study will be to expand our insight of the potential relationship in metabolic processes and neuropsychological functions in ASD. For example, based on the obtained data of the study we can determine whether there is a link between the tryptophan pathway and cognitive functions in autism. The project is based on a systematic and multidisciplinary approach using tracers for delineating the mechanism by which the metabolism of amino acids like TRP is involved in affective and cognitive functions in ASD. Using an innovative approach to the evaluation of amino acids has not been used in adults with ASD. In addition, the obtained data of the study holds promise to develop specific markers (metabolic and/or neuropsychological) for guiding the identification those individuals with increased risk of developing mood disturbances or cognitive impairment, and for predicting the therapeutic effect of a specific nutritional interventions in subjects with ASD.
Detailed description
This study investigates the metabolic profile of different amino acids and cognitive functions in adults and adolescents with ASD in comparison with age- and gender-matched healthy young adults. The study involves 1 screening visit of approximately 2 hours and 1 study day of 5 hours
The objective is to explore changes in amino acids (e.g. TRP pathway) in ASD and evaluate the function of TRP in neuropsychological functions by using the technique of stable isotope and our newly developed 'single pulse method' with multiple amino acid and keto-acid isotopes.
The aim of this study is to determine the underlying mechanism by which the metabolism of amino acids such as TRP are involved in mood and cognitive functions in ADS.
Study design
- Primary purpose
- Supportive care
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Healthy matched controls | Experimental | Other: stable isotope infusionStudy Day: The subject will arrive fasted. A catheter will be inserted in the arm for stable isotope infusion and blood sampling. The hand of the arm used for blood sampling will be placed in a thermostatically controlled warmed box that heats the air. Immediately after a baseline blood sample is taken, an infusion with stable isotopes will be administered by the research nurse. Stable isotopes are given to measure amino acid metabolism. Blood samples will be collected before and/or after infusion. Subjects will be asked to complete a list of questions regarding quality of life, mood and depression, diet. |
| Adults with Autism Spectrum Disorder | Experimental | Other: stable isotope infusionThe subject will arrive fasted. A catheter will be inserted in the arm for stable isotope infusion and blood sampling. The hand of the arm used for blood sampling will be placed in a thermostatically controlled warmed box that heats the air. Immediately after a baseline blood sample is taken, an infusion with stable isotopes will be administered by the research nurse. Stable isotopes are given to measure amino acid metabolism. Blood samples will be collected before and/or after infusion. Subjects will be asked to complete a list of questions regarding quality of life, mood and depression, diet. |
Who may qualify
- Ages
- 16 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (11 listed)
- Healthy male or female according to the investigator's or appointed staff's judgment
- Age 16 years or older
- Ability to walk, sit down and stand up independently
- Ability to lie in supine or elevated position for 4 hours
- Willingness and ability to comply with the protocol
Key exclusion criteria (13 listed)
- Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (for healthy group)
- Failure to give informed consent
- Established diagnosis of Insulin Dependent Diabetes Mellitus
- Metabolic diseases, including hepatic or renal disorders
- Presence of acute illness or metabolically unstable chronic illness
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| stable isotope infusionstable isotopes such as 15N2, TRP, 2H3-Leucine, L-[2H3]-3-Methylhistidine, 2H2-Glycine, 2-D-hydroxyproline, 1-13C-ketoisocaproic acid (KIC), L-[Guanido-15N2]-Arginine, L-[ureido-13C-2H2]-Citrulline), L-Glutamine-amide-15N, 1,2-13C2-L-Glutamic acid, 1,2-13C2Taurine, and 13C-Urea is given IV simultaneously | Other | Adults with Autism Spectrum Disorder, Healthy matched controls |
Primary outcome
Tryptophan turnover
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
17 secondary outcomes
leucine turnover
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
Whole body myofibrillar protein breakdown rate (reflecting muscle protein breakdown)
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
glutathione turnover
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
hydroxyproline breakdown (reflecting collagen breakdown)
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
glutamate turnover
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
taurine turnover
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
urea production
Time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes
Group differences in state of mood as measured by the Hospital Anxiety and Depression Scale (HADS),
Time frame: 1 day
Group differences in learning and memory as measured by Auditory Verbal Learning Test (AVLT)
Time frame: 1 day
Group differences in learning and memory as measured by Controlled Oral Word Association Test (COWAT),
Time frame: 1 day
Group differences in learning and memory as measured by Digit Span
Time frame: 1 day
Group differences in overall cognitive abilities as measured by Montreal Cognitive Assessment (MoCA)
Time frame: 1 day
Group differences in attention and executive functions as measured by Trail Making Test (TMT),
Time frame: 1 day
Group differences in attention and executive functions as measured by Stroop Color-Word Test (SCWT),
Time frame: 1 day
Adolescent/Adult Sensory Profile
Time frame: 1 day
Group differences in attention and executive functions as measured by Brief-A
Time frame: 1 day
Group differences in attention and executive functions as measured by PASAT
Time frame: 1 day
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Sep 2025.
- Derived from this study: PubMed 36166849Wierzchowska-McNew RA, Engelen MPKJ, Thaden JJ, Ten Have GAM, Deutz NEP. Obesity- and sex-related metabolism of arginine and nitric oxide in adults. Am J Clin Nutr. 2022 Dec 19;116(6):1610-1620. doi: 10.1093/ajcn/nqac277.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Marielle Engelen, PhD principal investigator
Texas A&M University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing stable isotope infusion in people with Autism Spectrum Disorder, run by Texas A&M University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 30 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Tryptophan turnover (time frame: 2, 5, 10, 15, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210 and 240 ± 5 minutes). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT02733120, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Sep 2025.