Investigating the effects of acute tryptophan loading on attention and impulsivity in adults with and without Attention Deficit Hyperactivity Disorder (ADHD)

Not Applicable

Completed

• Conditions: Attention Deficit Hyperactivity Disorder (ADHD); Mental and Behavioural Disorders

• Registration Number: ISRCTN15119603
• Lead Sponsor: King's College London

Brief Summary

2023 Results article in https://pubmed.ncbi.nlm.nih.gov/38033150/ (added 05/12/2023)

Detailed Description

Not available

Study Timeline

• Results First Posted: 1900-01-01
• Study Start: 2023-05-03
• Study Completion: 2023-09-30
• Last Update Posted: 8 January 2024

Recruitment & Eligibility

• Status: Completed
• Sex: All
• Target Recruitment: 144

Inclusion Criteria

All participants:
1. Adults aged 18-35 years

Healthy control participants (HC):
2. No diagnosis of ADHD and score on the Adult ADHD Self-Report Scale below the threshold indicative of ADHD.

ADHD
3. Existing current diagnosis of ADHD and score on the Adult ADHD Self-Report Scale above the threshold indicative of ADHD.
4. Either not receiving ADHD medication and have not received any for a period of at least 3 months or receiving medication for ADHD (psychostimulant or non-stimulant) and adhering to this with a rate of at least 70%.

Exclusion Criteria

1. Gluten or lactose intolerance, as participants will be asked to ingest a whey protein drink
2. Current or past diagnosis of nutritional, psychiatric (excluding ADHD) or neurological illnesses
3. Being pregnant/breastfeeding
4. Being a smoker (including e-cigarettes)
5. Currently taking medication known to affect the serotonergic system such as antidepressants
6. Learning disabilities
7. Following a restrictive diet (e.g. keto), as this might interfere with the experiment

Study & Design

• Study Type: Interventional
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Measured pre and post intervention (baseline and ~1 hour):<br>1. Attention measured using the computerised Test of Variable of Attention (TOVA) task (omission errors, response sensitivity, reaction time). <br>2. Motor impulsivity measured using the computerised Test of Variable of Attention (TOVA) task (commission errors).<br>3. Temporal impulsivity measured using the computerised Delay Discounting Task (indifference points, discounting function, area under the curve).<br>4. Cognitive impulsivity measured using the computerised Iowa Gambling Task (proportion of risky decisions, net score).

Secondary Outcome Measures

Name	Time	Method
There are no secondary outcome measures