A Phase 4 interventional study of Methylphenidate Hydrochloride and Placebo in Kbg Syndrome and ADHD - Combined Type, sponsored by Radboud University Medical Center. Recruiting at 1 site in Netherlands. Open to participants aged 6 Years to 20 Years. Per ClinicalTrials.gov, last updated 2026-08-11.
Sponsored by Radboud University Medical Center · Phase 4, Interventional, and Treatment
The goal of this clinical trial] is to learn about the effect of methylphenidate in children and adolescents with KBG syndrome. The main question it aims to answer is:
Participants will receive multiple blocks of treatment with methylphenidate and placebo and fill out various questionnaires.
KBG syndrome (KBGS) is a neurodevelopmental disorder (NDD) characterized by developmental delay and/or intellectual disability, typical facial features, skeletal and congenital anomalies.
Behavioural issues are a frequent feature, reported in 50-94% of persons with KBGS.The behavioural problems are diverse, and include attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), obsessive-compulsive disorder, anxiety, and difficulties in social situations. Van Dongen et al. systematically investigated the behavioural and cognitive phenotype of KBGS patients. This study showed a high level of distractibility, impulsivity and restless behaviour in KBGS patients. As a tertiary reference centre for KBGS in the Netherlands, the investigators notice there is an unmet need for evidence-based interventions for the behavioral problems related to KBGS. A previous survey amongst KBGS caretakers confirmed that (features of) attention-deficit/hyperactivity disorder (ADHD) are the most frequently reported behavioural problems in children with KBGS. Furthermore, the study results indicate that methylphenidate (MPH) has a good effect on ADHD-related symptoms in KBGS, as this is reported by most parents. The promising results from this first exploration on MPH in KBGS indicate that it seems even more effective than in the general population of children with ADHD. However, evidence-based data on optimal dosing and adverse events are lacking. Remarkably, only 2/12 KBGS patients who were treated with stimulants such as MPH had an official ADHD diagnosis. This indicates that patients with ADHD-related symptoms fitting with a probability diagnosis of ADHD, but who do not necessarily fit all the Diagnostic and statistical manual 5 (DSM-5) criteria for ADHD, may also benefit from drug treatment.
The investigators will examine the effectiveness of MPH in children and adolescents with KBGS and (a probability diagnosis of) ADHD, using an N-of-1 series (aggregated N-of-1) trial design.
Radboud University Medical Center is the lead sponsor of 959 studies on the registry; 134 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Methylphenidate hydrochloride in capsules
Drug: Methylphenidate Hydrochloride
Microcrystalline cellulose in capsules
Drug: Placebo
Methylphenidate hydrochloride in capsules
Microcrystalline cellulose in capsules
Strenghts and difficulties questionnaire, ADHD subscale
Minimum score 1, maximum score 10 (higher score is worse outcome).
Time frame: Baseline, and daily in week 1,3,5,7,9,11
Strenghts and difficulties questionnaire, emotional problems subscale
Minimum score 1, maximum score 10 (higher score is worse outcome).
Time frame: Baseline, and daily in week 1,3,5,7,9,11
Dutch shortened version of the Emotion Dysregulation Inventory (EDI) reactivity index
Minimum score 0, maximum score 28 (higher score is worse outcome)
Time frame: Baseline, and daily in week 1,3,5,7,9,11
Goal Attainment Scoring (GAS)
Personal goals, no minimum or maximum score
Time frame: Baseline, and at the end of week 1,3,5,7,9,11
Personal Questionnaire (PQ)
Personal goals, no minimum or maximum score
Time frame: Baseline, and at the end of week 1,3,5,7,9,11
Adverse Effects checklist for methylphenidate
Checklist of adverse effects
Time frame: Baseline, and daily in week 1,3,5,7,9,11
McMaster Family assessment device (FAD), subscale General Functioning
10 items, 4 point scale, maximum score 40
Time frame: Baseline, and at the end of week 1,3,5,7,9,11
Autism diagnostic observation scale (ADOS-2)
Minimum score 15, maximum score 60 (cut-off score for autism is 30)
Time frame: Baseline
Plan to share: Yes — Individual patients data that underlie the results after deidentification, study protocol, and statistical analysis plan will be shared upon request following publication, to researchers who provide a methodologically sound proposal.
Supporting information: Study protocol, Sap
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KBG syndrome
Radboud University Medical Center