Iron Deficiency, ADHD, Anxiety and Brain Function

Iron deficiency anaemia (IDA) refers to a low haemoglobin & iron store whereas in iron deficiency (ID) the haemoglobin levels are preserved. Even today, there is always much controversy about whether or not ID is symptomatic and should be treated but a little history should clarify this. We must remember that iron does far more than help carry oxygen around the body. Amongst other roles, it also plays an important part in how the brain works and this is what we will focus on in this excerpt.

Since the 19th century anaemia has been associated with cognitive defects including poor concentration. In the early 20th century, paediatricians noted developmental & learning difficulties in children with IDA. By the late 20th century, ie the 1970’s to 1980’s, it was becoming apparent that ID led to notable deficits in attention & memory. Studies in Nutrition & Behaviour and The American Journal of Clinical Nutrition^1,2 have alluded to this.

Over the past 30 years, researchers have continued to study whether low iron levels may affect attention, anxiety and overall cognitive performance particularly in children, teenagers and young adults. The term “brain fog” has been coined to cover all these areas.

Why Iron Matters for the Brain

Iron is essential for producing chemicals in the brain called neurotransmitters. These chemicals allow brain cells to communicate with one another.

Two of the most important neurotransmitters affected by iron are:

• Dopamine – involved in focus, motivation, reward and impulse control
• Serotonin – involved in mood and emotional balance

It’s easy to see why low iron levels can contribute to mood changes.

Iron is also needed for:

• Healthy development of brain cells
• Efficient nerve signalling through insulation of nerves
• Energy production inside the mitochondria (power house) of all cells including the brain

Research led by Dr John Beard and colleagues showed that iron deficiency can alter dopamine systems in the brain, even before anaemia develops³. Because dopamine plays a key role in attention and behaviour, this finding has important implications.

Brain imaging studies have also found that iron levels in certain brain regions are linked to executive function and working memory⁴.

Iron Deficiency and ADHD

ADHD is a complex condition influenced by genetics, brain chemistry and environmental factors. Dopamine differences are one of the most well-established biological findings in ADHD research.

In 2004, a study published in Archives of Paediatrics & Adolescent Medicine found that children with ADHD had significantly lower ferritin levels compared to children without ADHD even though they were not anaemic⁵.

A later clinical trial found that iron supplementation led to modest improvements in ADHD symptom scores in iron-deficient children⁶.

A large review of multiple studies concluded that lower ferritin levels are consistently found in children with ADHD, although researchers emphasised that iron deficiency does not explain all cases⁷.

What About University Students and Young Adults?

Iron deficiency is common in young adults especially:

• Women with moderate to heavy periods
• Students with restrictive or vegetarian diets
• Endurance athletes
• Individuals under high stress

Cognitive demands increase significantly at university. Sustained concentration, memory and mental stamina are essential.

Research in adolescent and young adult women has shown that even iron deficiency without anaemia can affect learning and memory. In one randomised study published in The Lancet, iron supplementation improved verbal learning and memory in iron-deficient teenage girls⁸.

Another study published in the American Journal of Clinical Nutrition found that young women with low ferritin experienced improvements in cognitive performance after iron treatment⁹.

These findings suggest that low iron may affect academic performance and mental clarity even when blood tests do not show anaemia.

Iron Deficiency and Anxiety

Anxiety symptoms can sometimes overlap with physical symptoms of iron deficiency.

Iron plays a role in regulating:

• The body’s stress response
• The autonomic nervous system (which controls heart rate and “fight-or-flight” responses)
• Neurotransmitters that help calm the brain

A large population-based study found that people with iron deficiency anaemia had higher rates of anxiety and mood disorders compared with those without deficiency¹⁰.

This does not mean iron deficiency causes anxiety disorders. However, low iron may contribute to symptoms such as:

• Restlessness
• Irritability
• Palpitations
• Sleep disturbance
• Reduced stress tolerance

For students and young adults already under pressure, these physical effects may amplify existing anxiety.

A Balanced View

It is important to be clear:

• Iron deficiency does not cause ADHD on its own.
• It does not replace psychological or psychiatric care.
• Not everyone with anxiety or attention difficulties has low iron.

However, iron deficiency is common, measurable and treatable. In people experiencing worsening concentration, fatigue, anxiety or academic decline especially if they are in a higher-risk group checking iron status can be clinically sensible.

Correcting a deficiency will not solve every cognitive or emotional difficulty. But if low iron is contributing, improvement can sometimes be meaningful.

Final Thoughts

The brain depends on iron more than many people realise. While iron deficiency is often discussed in terms of tiredness, research suggests it may also influence attention, memory and stress regulation particularly in younger populations.

An evidence-led approach means neither overestimating nor overlooking iron’s role. When symptoms and risk factors align, testing can provide clarity.

References

1. Pollitt E et al. Iron deficiency and cognitive test performance in preschool children. Nutrition and Behavior. 1983;1(2):137–146.
2. Soewondo S et al. Effects of iron deficiency on attention and learning processes in preschool children: Bandung, Indonesia. American Journal of Clinical Nutrition. 1989; 50(3 Suppl):667–674
3. Beard JL. Iron deficiency alters brain development and functioning. J Nutr. 2003;133(5 Suppl 1):1468S–1472S.
4. Pujol J, et al. Brain iron concentration in ADHD: a quantitative MRI study. J Child Psychol Psychiatry. 2012;53(7):720–728.
5. Konofal E, et al. Iron deficiency in children with ADHD. Arch Pediatr Adolesc Med. 2004;158(12):1113–1115.
6. Konofal E, et al. Effects of iron supplementation on ADHD in children. Pediatr Neurol. 2008;38(1):20–26.
7. Cortese S, et al. Iron and ADHD: systematic review and meta-analysis. J Am Acad Child Adolesc Psychiatry. 2012;51(6):647–655.
8. Bruner AB, et al. Randomised study of cognitive effects of iron supplementation in non-anaemic iron-deficient adolescent girls. Lancet. 1996;348(9033):992–996.
9. Murray-Kolb LE, Beard JL. Iron treatment normalizes cognitive functioning in young women. Am J Clin Nutr. 2007;85(3):778–787.
10. Chen MH, et al. Association between psychiatric disorders and iron deficiency anemia. BMC Psychiatry. 2013;13:161.