An observational study in ADHD, Benign Joint Hypermobility Syndrome and ADHD - Attention Deficit Disorder With Hyperactivity, sponsored by Antalya Training and Research Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 6 Years to 12 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-23.
Sponsored by Antalya Training and Research Hospital · Observational
This cross-sectional observational study investigates the clinical and biochemical relationship between Attention-Deficit/Hyperactivity Disorder (ADHD) and Benign Joint Hypermobility Syndrome (BJHS) in pediatric patients. The primary objective is to evaluate the prevalence of BJHS in children diagnosed with ADHD and compare serum prolidase levels with those of healthy controls. The study also explores whether the severity of ADHD symptoms correlates with serum prolidase activity. Clinical assessments include the Conners Parent Rating Scale, Beighton Score, and serum prolidase measurement using ELISA. This research aims to provide new insights into the potential connective tissue-neurodevelopmental link and contribute to early screening frameworks for children with ADHD.
Attention-Deficit/Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity, often presenting in early childhood. Although traditionally viewed as a purely behavioral and neurochemical condition, increasing evidence suggests a potential overlap with systemic and somatic findings, including those related to connective tissue disorders. One such condition is Benign Joint Hypermobility Syndrome (BJHS), a clinical entity involving increased joint flexibility due to altered collagen structure or metabolism.
Recent hypotheses have proposed a shared pathophysiological basis between neurodevelopmental disorders and connective tissue abnormalities, possibly mediated by enzymatic and inflammatory pathways. Prolidase is a cytosolic exopeptidase that plays a key role in collagen turnover and proline recycling. It has been implicated in various connective tissue disorders and may also influence neuroinflammatory processes. Thus, prolidase activity may serve as a biochemical bridge between BJHS and ADHD.
This cross-sectional observational study was conducted to investigate the clinical and biochemical associations between ADHD and BJHS in a pediatric population. Specifically, the study aimed to:
A total of 171 children aged 6 to 12 years participated in the study: 86 with a clinical diagnosis of ADHD (based on DSM-5 criteria) and 85 age- and sex-matched healthy controls without psychiatric or systemic illnesses. Participants in the ADHD group were recruited from the Child and Adolescent Psychiatry Department of Antalya Training and Research Hospital. Control subjects were selected from the general pediatric outpatient population, ensuring the absence of known neurodevelopmental or rheumatological disorders.
All participants underwent a standardized assessment battery. ADHD symptom severity was quantified using the Conners' Parent Rating Scale-Revised: Short Form (CPRS-R:S), which also allowed classification into ADHD subtypes. Joint hypermobility was assessed using the Beighton scoring system, with a threshold score ≥4 indicating hypermobility. Sociodemographic data were collected via structured interviews with caregivers. Venous blood samples were obtained to determine serum prolidase levels, analyzed using a validated ELISA method.
Data were statistically analyzed to evaluate group differences in Beighton Scores and prolidase levels, as well as correlations between biochemical markers, ADHD severity scores, and ADHD subtype classifications. Subgroup analyses were also conducted to assess whether prolidase activity or joint hypermobility was more strongly associated with specific ADHD presentations (e.g., inattentive vs. combined type).
By integrating clinical, physical, and biochemical data, this study seeks to offer a multidimensional perspective on ADHD, moving beyond traditional neurocognitive models. The findings may support the development of new screening and diagnostic strategies, particularly for pediatric patients who present with both behavioral symptoms and physical signs such as joint hypermobility. Additionally, this research may help identify candidate biomarkers for early intervention and interdisciplinary assessment in child psychiatry and pediatric rehabilitation settings.
1,817 studies on the registry are indexed under Attention Deficit Disorder with Hyperactivity; 296 are open to participants now.
This study's enrollment of 171 is above the median of 127 across 329 observational studies indexed under Attention Deficit Disorder with Hyperactivity.
Browse Attention Deficit Disorder with Hyperactivity studies →Antalya Training and Research Hospital is the lead sponsor of 104 studies on the registry; 12 are open to participants now.
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The study population consisted of children aged 6 to 12 years, including 86 patients diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) according to DSM-5 criteria and 85 age- and sex-matched healthy controls. Patients were recruited from the Child and Adolescent Psychiatry outpatient clinic of Antalya Training and Research Hospital. Control subjects were selected from the general pediatric outpatient department. All participants were evaluated for ADHD symptom severity, joint hypermobility, and serum prolidase levels.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
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DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Children aged 6 to 12 years who were clinically diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) according to DSM-5 criteria. Participants in this cohort were recruited from the Child and Adolescent Psychiatry outpatient clinic of Antalya Training and Research Hospital. Each child underwent a detailed clinical evaluation including the Conners' Parent Rating Scale-Revised: Short Form (CPRS-R:S) to determine ADHD symptom severity and subtype. Joint hypermobility was assessed using the Beighton Score, and venous blood samples were collected to measure serum prolidase enzyme activity using ELISA. No therapeutic intervention was applied; this is a non-interventional observational group.
This group consisted of age- and sex-matched healthy children between 6 and 12 years of age with no history of psychiatric, neurological, or systemic illness. Control participants were selected from the general pediatric outpatient population and underwent the same evaluations as the ADHD group. These included the Conners' Parent Rating Scale-Revised: Short Form (CPRS-R:S), Beighton Score assessment for joint hypermobility, and serum prolidase measurement via ELISA. The purpose of this group was to provide a baseline comparison for clinical and biochemical parameters without any intervention applied.
Incidence of comorbid Benign Joint Hypermobility Syndrome (BJHS) in children with ADHD
The primary outcome is to evaluate the incidence of Benign Joint Hypermobility Syndrome (BJHS) among children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), compared to healthy controls. Diagnosis of BJHS will be based on a Beighton score ≥5 and clinical evaluation.
Time frame: At enrollment (single visit)
Beighton Score for Joint Hypermobility
Generalized joint hypermobility will be assessed using the Beighton scoring system (range: 0-9), with a cutoff value of ≥5/9 as a diagnostic threshold. The total Beighton scores of children with ADHD (ages 6-12) will be compared to healthy controls.
Time frame: At enrollment (single visit)
Serum Prolidase Level
Fasting venous blood samples will be collected from all participants and serum prolidase levels will be measured using ELISA. Prolidase enzyme activity (U/L) will be compared between the ADHD group and healthy controls.
Time frame: At enrollment (single visit)
Sociodemographic Characteristics
Sociodemographic data including age (in years), sex, height (in cm), weight (in kg), and socioeconomic status (classified as 0: low, 1: moderate, 2: high) will be collected and compared between groups.
Time frame: At enrollment
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — Individual participant data that underlie the results reported in this study (including de-identified demographic, clinical, and biochemical data such as age, sex, Conners' scores, Beighton scores, and serum prolidase levels) will be shared upon reasonable request to the corresponding investigator.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report
Time frame: IPD and supporting documents will be available upon reasonable request after publication of study results. Requests can be submitted via email to the principal investigator. All shared data will be de-identified.
Access criteria: Qualified researchers affiliated with academic or research institutions may request access to de-identified individual participant data (IPD) and supporting documents (e.g., study protocol, statistical analysis plan) by contacting the principal investigator via email. All requests will be reviewed and must include a data use agreement. Data will be provided electronically under secure conditions, only for non-commercial scientific purposes.
Ran from Apr 2025 to primary completion in Sep 2025, 5 months.
Of 85 non-industry observational studies under Attention Deficit Disorder with Hyperactivity, half reached primary completion within 35 months of starting (the median), counting those still running; a quarter within 18 and three quarters within 69. This study's 5 months is below that.
Counting every sponsor, half of 95 studies reached it within 35 months; a quarter within 20 and three quarters within 69.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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