Evaluation of elements in hair samples of children with developmental language disorder (DLD)

ABSTRACT

Background

Recent studies have highlighted a role for trace elements and toxic metals across neurodevelopmental disorders, including developmental stuttering, Autistic Spectrum Disorders (ASD), and Attention Deficit/Hyperactivity Disorder (ADHD). However, these environmental influences have yet to be explored in relation to Developmental Language Disorder (DLD).

Methods

Elemental hair composition of seven elements; zinc (⁶⁴Zn), magnesium (²⁶Mg), iron (⁵⁷Fe), potassium (³⁹K), aluminum (²⁷Al), lead (²⁰⁸Pb), and barium (¹³⁸Ba) were analyzed in hair samples from 35 children affected by DLD and 35 controls with typical language development (TLD) using both inductive coupled plasma optical emission spectroscopy (ICP–OES) and inductive coupled plasma mass spectroscopy (ICP–MS).

Results

The concentration of ⁶⁴Zn was significantly lower in the hair of DLD group compared to the TLD control group. All other elements showed similar levels between cases and controls. This pilot study demonstrates the utility of trace elements and toxic metals screening in relation to language disorders and the use of hair samples in such investigations.

Conclusion

The finding that zinc levels differed between cases and controls could represent a clinically relevant result and should be replicated in larger sample size across time. A wider battery of related elements will help to better understand the role of trace elements and toxic metals in DLD.

KEYWORDS:

• Developmental language disorder
• metals
• human hair
• ICP–MS
• ICP–OES
• elements
• trace elements
• toxic metals
• typical language development

Acknowledgments

The authors are thankful to Princess Haya Biotechnology Center for providing the appropriate environment for analysis.

Statement of human rights

The research was conducted in accordance with the 1964 Helsinki Declaration. The protocol of the study was approved by King Abdullah University Hospital (KAUH) institution review board (IRB) [Approval No. 10/215/2444]. Moreover, verbal and informed consent was obtained from the parents of the examined children before inclusion into the study, and hair sampling was performed in the presence of parents.

Consent to participate

Informed consent was obtained from the parents of all children enrolled in the study.

Data availability

Relevant documentation or data are available upon request.

Author contributions

A.B. and M.A; methodology, A.B.; software, A.B.; validation, A.B. and M.A.; formal analysis, A.B.; M.A writing – original draft preparation, M.A., M.EL., D.F.N and F.A; writing – review and editing, H.K and A.A; visualization, A.B.; supervision, M.A.; project administration. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Jordan University of Science and Technology under Grant [number 558-2015].

Notes on contributors

Ayat Bani Rashaid

Ayat Bani Rashaid is an assistant professor in the department of Chemistry at Jordan University of Science and Technology. Her research interests include clinical and medicine Biochemistry (i.e., biochemistry of autism spectrum disorder).

Mazin Alqhazo

Mazin Alqhazo is an associate professor of Speech-Language pathology in the Department of Rehabilitation Sciences in Jordan University of Science and Technology. His research interests are mainly driven by five related lines of investigation: (1) examining the linguistic aspects of stuttering, (2) examining the internalized feelings of people who stutter, (3) examining the attitudes toward stuttering, (4) examining the biochemistry of people who stutter, and (5) Examining the anatomical and the functional differences in the brain of people who stutter.

Dianne F. Newbury

Dianne F. Newbury is a molecular geneticist who studies genetic contributions to childhood neurodevelopmental disorders. Her investigations specifically focus around speech and language impairment and its relationship to disorders such as dsyslexia. Dianne has a lab at the Wellcome Trust Centre for Human Genetics at Oxford University and is a senior lecturer at Oxford Brookes University. Her research is funded by a Career Development Fellowship from the Medical Research Council.

Heba Kanaan

Heba Kanaan is a research assistant in the department of Chemistry in Jordan University of Science and Technology

Mohammad El-khateeb

Mohammad El-khateeb is a professor in inorganic chemistry in the department of chemistry in Jordan University of Science and Technology. His research interests are inorganic and organometallics.

Ahmad Abukashabeh

Ahmad Abukashabeh is a chemical technician in Jordan Atomic Energy Commission.

Feda Al-Tamimi

Feda Al-Tamimi is an Associate Professor of Linguistics and Speech Sciences in the Rehabilitation Sciences department in Jordan University of Science and Technology. His research interests include language disorders and Syntactic Deficits as well as language Acquisition.