Study Links Low Iron to ADHD

A study suggests that iron deficiency may contribute to attention deficit hyperactivity disorder (ADHD) in children.Researchers from France also say children with ADHD and iron deficiencies exhibit more severe symptoms.Investigators suggest that iron supplementation may benefit children with ADHD and iron deficiency. 

Iron Stores Predict Symptom Severity

Past research has linked iron deficiency in infancy to slower braindevelopment and poorer school performance later in childhood. Animal studies have linked iron deficiency to abnormal muscle movement or restlessness. Iron deficiency is also common in people with the movement disorder known as restless legs syndrome.Lead researcher Eric Konofal, MD, PhD, tells WebMD that these earlier findings led him to question whether iron deficiency plays a role in ADHD．

In an effort to answer the question, Konofal and colleagues measured bloodlevels of the protein ferritin in 53 children with ADHD and 27 children without ADHD but who had a mild reading disability. Ferritin allows the body to store iron and is used as a measure of iron levels.

Eighty-four percent of children with ADHD appeared to have abnormally low ferritin levels, compared with 18% of children without ADHD.

The children with the most severe iron deficiencies were also the most inattentive, impulsive, and hyperactive. This led the researchers to conclude that "low iron stores may explain as much as 30% of ADHD severity."

The researchers say the reason for the low iron levels in children with ADHD is unclear.

Konofal says he hopes to collaborate with ADHD researchers in the United States on a much larger study to confirm the findings.He added, however, that kids with ADHD should be tested for iron deficiency.　"If it is involved, I believe iron deficiency is responsible for only a very small segment of the problems associated with ADHD," says Coleman, professor or pediatrics at the University of North Carolina Medical Center.

Abnormal brain iron levels 'may be a biomarker of ADHD'

According to a recent study, the number of children diagnosed with attention deficit hyperactivity disorder in the US increased by 42% between 2003-04 and 2011-12. The increase sparked concern that many children are being incorrectly diagnosed with the condition. 

But a new study published in the journal Radiology details a biomarker of ADHD that is identified through a brain imaging technique, which researchers say could help prevent misdiagnosis.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that causes concentration problems, uncontrollable behavior and overactivity. 

ADHD onset usually occurs in childhood and the condition can last well into adulthood.

According to the research team, including Dr. Vitria Adisetiyo, postdoctoral research fellow at the Medical University of South Carolina, there has been much worry over the increasing rates of ADHD diagnosis in the US, particularly since around two thirds of those diagnosed receive psychostimulants - such as Ritalin - to help treat their condition.

Psychostimulants work to regulate impulsive behavior and improve attention span. But the medication also increases the levels of dopamine in the brain - a neurotransmitter linked to addiction - which may increase the likelihood of drug abuse.

In this latest study, the researchers set out to find a way to help prevent incidence of ADHD misdiagnosis, so children and adolescents are not subject to psychostimulant medication if it is not needed.

ADHD patients 'may have abnormal iron absorption into the brain'

The team wanted to see whether levels of iron in the brain could be a potential biomarker for the diagnosis of ADHD.

In 2006, study co-authors Joseph Helpern, PhD, and Jens Jensen created a magnetic resonance imaging (MRI) technique - called magnetic field correlation imaging.

Through magnetic field correlation imaging, researchers found that ADHD patients without a history of psychostimulant use had low brain iron levels, which may be a biomarker.

Using this technique, the researchers measured the brain iron levels of 22 children and adolescents with ADHD, alongside 27 children and adolescents without the condition. Of participants with ADHD, 12 had never received psychostimulant medication for their condition. Participants' iron levels in their blood were also measured.

The study results revealed that the 12 patients with ADHD who did not have a history of psychostimulant medication had much lower brain iron levels, compared with the remaining ADHD patients who had used psychostimulants and the healthy children and adolescents.

In fact, the team found that ADHD patients who had a history of psychostimulants had similar brain iron levels to the healthy patients, indicating that psychostimulant medication may normalize brain iron levels.

"Our research suggests that iron absorption into the brain may be abnormal in ADHD given that atypical brain iron levels are found even when blood iron levels in the body are normal," explains Dr. Adisetiyo. "We found no differences in blood iron measures between controls, medication-naive ADHD patients or pscyhostimulant-medicated ADHD patients."

Dr. Adisetiyo notes that at present, ADHD diagnosis relies on the patient taking part in subjective clinical interviews and questionnaires. But the team says their magnetic field correlation imaging technique could be used to improve ADHD diagnosis and treatment, as it can detect low iron levels in the brain.

They note that if their findings are duplicated in larger studies, the imaging technique could be used to identify the patients who would benefit from psychostimulant medication, while preventing others from being subject to the drugs if they are not needed.

Dr. Adisetiyo adds:

"We want the public to know that progress is being made in identifying potential noninvasive biological biomarkers of ADHD, which may help to prevent misdiagnosis. We are currently testing our findings in a larger cohort to confirm that measuring brain iron levels in ADHD is indeed a reliable and clinically feasible biomarker."

有关人体内的铁元素与多动症的研究

一项研究表明，缺铁可能导致儿童多动症（ADHD）。法国的有关研究人员表示，体内铁缺失的多动症的儿童症状更加严重。专业人员建议，多动症和铁缺失儿童应多多补充铁元素。

根据体内的铁元素储量可以预测多动症病情

早期研究认为，婴儿期铁缺失可能会导致大脑发育迟缓，从而影响后期的学习成绩。研究人员还发现，动物体内缺铁会导致肌肉运动异常或者躁动不安。患有多动腿综合征的患者体内的铁含量也偏低。首席研究员兼医学博士埃里克·科诺法尔（ Eric Konofal）表示，早期的这些发现让他怀疑铁元素的缺失与多动症之间也存在着一定的联系。为了证实这个问题，科诺法尔和他的同事分别观测了53名多动症儿童和27名有轻度阅读障碍的儿童体内的铁蛋白水平。铁蛋白用来存储体内的铁元素，并用作衡量人体内铁水平的指标。结果表明，有84%的多动症儿童铁蛋白水平异常偏低，而相比之下，铁水平偏低的健康儿童为18%。在研究中，铁缺失较为严重的的儿童在注意力、易冲动和极度活跃方面的表现也是最糟糕的。对此，研究人员得出结论：体内铁元素含量较低的话会使多动症症状加重３０％。

但目前，到底是什么原因造成了多动症儿童体内的铁严重缺失还尚未得知。科诺法尔表示，他希望与美国多动症专业研究人员合作开展一项大型研究以发现多动症儿童体内铁缺失的原因，另外多动症儿童的父母应及时检测孩子体内的铁含量水平。

脑铁水平可能是检验多动症的生物标志物

注：生物标志物是一种检测物质，指示一个正在发生的特殊过程或结果

一项研究表明，2003-04年至2011-12年间，美国诊断出患有多动症障碍的儿童人数增加了42%。人们不由担心越来越多的孩子会患上多动症。《影像诊断学》(Radiology)杂志上的一项新研究详细介绍了一种脑成像技术，这种技术可以识别人体大脑中多动症的生物标志物。研究人员表示，这极大减少了多动症的误诊几率。

注意缺陷多动障碍（ADHD）——俗称为多动症是一种神经性发育障碍，这种病会导致患者注意力不集中、行为失控和过度活跃。多动症的发病通常在儿童时期，这种情况可以一直持续到成年。维特里亚．阿迪塞蒂约（Vitria Adisetiyo）是南卡罗来纳医科大学的博士后研究员,他所带领的研究团队表示，越来越多的人担心美国多动症患者的数量会持续增加,尤其是大约三分之二的多动症患者为了缓解病情而滥用兴奋剂。兴奋剂的作用是调节冲动行为并且提高注意力。但是，使用这种药物也会增加大脑中多巴胺的分泌（多巴胺是一种与成瘾有关的神经递质），因此使用兴奋剂来治疗多动症可能会增加药物滥用的可能性。

多动症患者大脑铁吸收异常

该研究团队的目的是探究大脑中的铁水平是否可能成为诊断多动症的潜在生物标志物。2006年，参与该项研究的约瑟夫．赫尔彭（Joseph Helpern）博士和延斯．延森（Jens Jensen）研发了一种磁共振成像技术——磁场相关成像。通过磁场相关成像技术，研究人员发现，未曾使用过兴奋剂的多动症患者脑铁水平较低，这可能是一种生物标志物。利用这项技术，研究人员分别观察了22名患有多动症的儿童和青少年的脑铁水平，以及27名健康儿童和青少年的脑铁水平。在患有多动症的２２名参与者中，有12人从未使用过兴奋剂来治疗，除此之外，研究人员还观测了参与者血液中的铁水平。

研究结果显示，12名没有服用过兴奋剂的多动症患者的脑铁水平远远低于其余使用过兴奋剂的患者以及健康的儿童和青少年的脑铁水平。并且使用过兴奋剂治疗的多动症患者的脑铁水平几乎达正常水平，这表明服用兴奋剂可能会使脑铁水平趋于正常。

对此，阿迪塞蒂约博士解释说，“我们的研究表明，即使体内的血液铁水平正常，但多动症患者的大脑对铁吸收可能是处于异常状态。我们还对比了使用常规药物治疗的多动症患者和使用兴奋剂治疗的多动症患者，发现两者之间的血液铁水平没有差异。”他指出，目前多动症的诊断依赖于患者的主观临床交谈和调查。但该研究团队表示，因为磁场相关成像技术可以检测到大脑的铁水平，所以该技术可以用来提高多动症的诊断准确率，并且改善治疗。如果这种技术应用到更大型的研究中，那么便可以识别出那些使用兴奋剂治疗有所改善的患者，同时可以让多动症患者根据自身需要来决定是否要使用兴奋剂进行治疗。

阿迪塞蒂约博士补充道：“我们希望公众知道，在识别多动症潜在的非侵入性生物标志物方面取得了很大进展，这极大降低了多动症的误诊率。”