Iron profile in children with ADHD

Introduction

ADHD is defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) as a chronic and pervasive pattern of inatte-ntion, hyperactivity, impulsivity, or both, that disrupts functioning or development.⁽¹⁾ ADHD is the most prevalent neuro develop-mental disorder, affecting around 5% of school-aged children worldwide. ⁽²⁾ Up to 75% of individuals with ADHD experience impaired symptoms throughout adulthood. ⁽³⁾

ADHD frequently co_occurs with other dysfunctions (e.g., executive dysfunction and emotional dysregulation) or disorders (e.g., mood, anxiety, and addictions) ⁽⁴⁾. Attention-Deficit/ Hyperactivity Disorder (ADHD) exerts a profound and persistent impact on individuals' social functioning across the lifespan. It frequently manifests in early life as disruptive behaviors, which are often associated with sub-optimal performance on standardized assess-ments and impaired social interactions.

These early difficulties may progress into more severe outcomes, including involvement in criminal activities, substance dependence, diminished motivation, school exclusion, and adverse effects on occupational development in adulthood. Moreover, ADHD has been consistently linked to a reduced health-related quality of life. Collectively, these challenges contribute to a substantial economic burden associated with the disorder. ⁽⁵⁾

Currently, a definitive cause of Attention-Deficit/Hyperactivity Disorder (ADHD) has not been established. However, it is widely accepted that the disorder arises from a complex interplay of multiple risk factors, including genetic susceptibility, perinatal complications, and various socioeconomic influences. ^(6,7,8,9) Iron deficiency has been suggested as a potential contributing factor in the development of Attention-Deficit/ Hyperactivity Disorder (ADHD). Infants and children, in particular, appear to be more vulnerable to exhibiting ADHD-related symptoms in the presence of insufficient iron levels ^(10,11,12), Conversely, a higher prevalence of iron deficiency has been observed among cohorts of children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD), further supporting the potential association between iron status and the manifestation of ADHD symptoms. ⁽¹³⁾

Furthermore, emerging evidence indicates a possible association between reduced maternal ferritin levels during pregnancy (ferritin being the key protein responsible for iron storage) and an elevated risk of Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms in the offspring during infancy and early childhood^{. (7)}

Iron plays a crucial role for many neurocognitive processes, this can be observed in iron-deficient patients, where impaired neuro-cognitive symptoms are frequently reported including; depression, anxiety, difficulty concentrating and the patient-coined term ‘brain fog. ^(14,15)

In neurocognition, iron is involved in nerve myelination, oxygen transport to the brain, neurotransmitter synthesis and transporter expression, with the latter two incorporating dopamine synthesis and dopamine transporter (DAT) expression and, as such, is currently proposed as the most plausible mechanism for iron deficiency to trigger ADHD symptoms. ⁽¹⁶⁾

Children with ADHD may experience low serum iron levels due to several factors. Different study suggested that these children often have difficulty absorbing iron from their diet, which leads to lower iron levels in the bloodstream. Additionally, iron plays a crucial role in the production of dopamine, a neuro-transmitter essential for regulating attention and behavior. A deficiency in iron can impair dopamine synthesis, contributing to symptoms of inattention and impulsivity. Furthermore, children with ADHD may have poor eating habits that lack essential nutrients, increasing their risk of developing iron deficiency^{. (27)}

Methods:

This study was a case control study conducted upon 100 ADHD children they were recruited from Pediatric Neuro psychiatric Outpatient Clinic of Minia University Hospital, they were diagnosed through DSM_5 ⁽¹⁾ diagnostic criteria, their symptoms severity was evaluated by conners' parent rating scale ^(17), and 100 healthy children serving as controls

Children with age range (5–9) years with a confirmed diagnosis of ADHD based on clinical evaluation and standardized diagnostic criteria (e.g., DSM-5), no concurrent severe neurological or psychiatric disorders and written informed consent from parents or legal guardians were included in this study. Children with chronic medical conditions that could affect iron metabolism (e.g., chronic kidney disease, liver disease, or hematological disorders), children receiving iron supplementation or other treatments that could interfere with iron status and incomplete medical or laboratory data were excluded from this study. Complete history, general and neurological examination was done to all studied children. Moreover, CBC and iron profile were done to all studied children. 

Diagnosis of ADHD

The diagnosis of ADHD was done upon clinical assessment and  according to Diagnostic and Statistical Manual of Psychiatric Disorders (DSM-5: American Psychiatric Association

2013). While the degree of severity of ADHD and its sub scores were evaluated through Conner's parent score which formed of 80

questions^{. (1,17)}

Laboratory Assessment Methodology:

Blood samples were collected from all participants (ADHD children and controls) following standard venipuncture techniques. A total of 5 mL of venous blood was drawn from each participant after an overnight fast (8-12 hours). The blood samples were distributed as follows:

Complete Blood Count (CBC):

2 mL of whole blood was collected in EDTA-containing tubes (BD Vacutainer® K2EDTA tubes). CBC parameters were analyzed within 2 hours of collection using an automated hematology analyzer (Sysmex XN-1000™, Sysmex Corporation, Japan). The following parameters were measured: Hemoglobin (HB), Total leukocyte count (TLC), Platelet count, Mean corpuscular volume (MCV), Differential cell count including lymphocyte and neutrophil percentages.

Iron Profile Parameters:

3 mL of blood was collected in serum separator tubes (BD Vacutainer® SST™ tubes). After allowing the blood to clot for 30 minutes at room temperature, the samples were centrifuged at 3000 rpm for 10 minutes to separate the serum. The following parameters were measured: Serum Ferritin: Measured using a chemiluminescent micro-particle immunoassay (CMIA) on the ARCHITECT i2000SR system (Abbott Laboratories, USA).

Serum Iron: Measured using the colorimetric method with ferrozine as the chromogen

(Beckman Coulter AU680, USA). Total Iron-Binding Capacity (TIBC): Measured using the colorimetric method (Beckman Coulter AU680, USA). Transferrin Saturation: Calculated as the ratio of serum iron to TIBC multiplied by 100.

Ethical Committee:

• An official letter was granted from the Research Ethics Committee of the Faculty of Medicine, Minia University with ethical number 1153/04/2024
• Before the conduction of study, consent was obtained from the children and their caregivers who were willing to participate in the study, after explaining the nature purpose of the study.
• Study subject had the right to accept, refuse or withdraw from the study without rational any time.

Statistical Analysis:

Data were analyzed using descriptive statistics. Continuous variables were expressed as medians with interquartile ranges (IQR), while categorical variables were expressed as frequencies and percentages. The data were analyzed to identify potential correlations between iron status and ADHD symptoms, as well as other clinical parameters.

Results

This study showed that the median age of ADHD children was 7 years (IQR: 5–9), 63% male, 37% females. Most of the ADHD children live in urban areas, 40% only had positive consanguinity, while the median age of the controls was 6 years (IQR: 6–8.75), 66% male, 34%female, with more of them lived in urban areas.

Discussion:

Attention deficit hyperactivity disorder (ADHD) is characterized by challenges in domains of impulsivity, hyperactivity and inattention, it is estimated to affect 5–7% of children and adolescents worldwide ^(18).

This study showed there was no significant difference regarding the body weight of children between ADHD children and controls. Wang et al reported that there was no statistically significant difference between the studied groups regarding the body weight. ⁽¹⁹⁾

This study showed that hemoglobin (HB) concentration was significantly lower in ADHD group compared to control group (p<0.001), In agreement with this result was Wang et al reported that there was statistically significant difference between the studied groups regarding Hb which significantly lower in ADHD children. ⁽¹⁹⁾

The current study showed a significant higher lymphocytic count was noted in ADHD children than controls which reflect the possibility of immune system involvement in ADHD.

Many studies found higher lymphocytic count was noted in ADHD and suggested that inflammation might play a role in the etiopathogenesis of ADHD^{. (20-21-22-23)}

Moreover, this study showed that serum ferritin levels were slightly lower in ADHD children than controls but total iron-binding capacity (TIBC) was significantly higher than controls suggesting altered iron metabolism. Additionally, transferrin saturation and serum iron were significantly lower in ADHD children. These findings suggest that immune response and iron deficiency may play a role in ADHD, warranting further research on their impact on neurodevelopment.

Bener also found that there was significant lower serum iron and Hb in ADHD cases. Otherwise, there was statistically significant difference between the studied groups regarding ferritin. ⁽²⁴⁾

El-Mazary et al also found that there was significantly lower serum ferritin in ADHD cases than controls. ⁽²⁵⁾

However, Hassaan et al, who reported that there was no significant statistical difference between ADHD patients and controls regarding Hb. ⁽²³⁾  As well, the current results contrast with Avval et al, who reported that no significant difference was observed in TIBC between the two groups. ⁽²⁶⁾