Niger J Paediatr 2019; 46 (1):1 – 4
Accepted: May 15th 2019
pus per se plays important roles in
most prevalent micronutrient mal-
the consolidation of information
Asindi AA (
nutrition globally. It is known to
from short-term memory to long-
Department of Paediatrics,
affect both children and adults
term memory, and in spatial mem-
University of Calabar, Nigeria
ory that enables navigation.
largely in the developing coun-
Low iron levels in pregnant
tries. Iron is not only important
women correlates with low ferritin
for haemoglobin synthesis but
levels in their foetus and newborns
also for normal brain develop-
whereby several studies have
ment. In the body, the ferrous
clearly demonstrated the effect of
formis converted into ferritin
iron on developmental milestone
which is the active molecule. The
regarding cognition and behaviour.
brain is especially sensitive to
Iron deficiency early in life, there-
variation in iron availability, in
fore, confers irreversible brain
part due to the high metabolic
dysfunction even after complete
demands of the brain that are sup-
brain iron repletion. Iron therapy
ported by iron. Iron is necessary
and replenishment of brain ferritin
basic neuronal processes such
may revert to normal cognitive
functions in adults and adolescents
production, and energy metabo-
not in children. Rich sources of
lism. With neuroimaging support,
iron are meat, liver, dark leafy
Globus pallidus, caudate nucleus,
green vegetables, fish, poultry,
putamen, substantia nigra and the
peas and beans. Pregnant women
hippocampus have been of pri-
require routine daily iron supple-
mary interest in studies of iron
ment; lactating woman and all
because they show robust and
children should be fed balanced
quantifiable levels of iron content.
diet. Special iron supplement
Furthermore, these regions are
should be provided for preterm and
central to cognitive abilities that
develop across childhood and
the age of two months.
adolescence, such as processing
speed, cognitive-motor control,
reward-processing, and working
hood, Intellectual impairment.
memory function. The hippocam-
Dietary iron is converted to ferritin which is the active
form of iron in the body. Apart from haemoglobin syn-
Iron deficiency (sideropenia) is the most prevalent nutri-
thesis, ferritin is a necessary element in the development
ent deficiency in the world afflicting an estimated 2.5 – 5
and functioning of the nervous system. Infants and chil-
is more common in developing coun-
dren with low ferritin levels are at riskof impairment of
tries where 46 – 66 per cent of all children under 4 years
brain development and function.
age are anaemic.
More than 50 per cent of paediat-
ric anaemia in the developing countries can be attributed
Because iron is involved in the function of various en-
iron-deficiency with a peak prevalence among those
zymes and neurotransmitters in the central nervous sys-
the 6-24 months age bracket. Maternal sideropenic
tem hence low serum levels of ferritin is postulated to
lower seizure threshold, including febrile convulsions.
anaemia complicates 30 – 50 per cent of pregnancies in
developing countries; in contrast, in developed countries
Restless Legs Syndrome appears to be related to deficits
brain iron content and metabolism. Other conditions
where iron supplements are routinely administered, this
figure is less than one percent. The most common cause
associated with deficeit in brain iron contents and me-
foetal/neonatal iron sideropenia is maternal iron defi-
tabolism in children and adolescents include syn-
affective respiratory crises,
ciency. Infants born to mothers suffering from iron-
deficiency anaemia have lower iron levels and are more
prone to anaemia.
This review focuses on what impact iron deficiency
hason the intelligence of children.
ence or education by perceiving, discovering, or learn-
ing. It is synonymous with appreciation, cognition and
Neurobiology and neurophysiology of Iron
intelligence. It requires the storage of information
Human nutritional requirement for brain function in-
(memory) in the cerebral cortex and the retrieval (recall)
clude proteins, certain types of fat, iron, zinc, copper,
same in appropriate circumstances. Children exposed
iodine, selenium, vitamin A, choline and folate. Iron is
iron deficiency both in utero and in the newbornpe-
the most abundant transition metal within the brain, and
will suffer irreversible mental deficiency. Iron-
vital for a number of cellular processes including neu-
deficiency anaemia is common during the second and
rotransmitter synthesis, myelination of neurons and mi-
third years of life and has variably been associated with
tochondrial function. Theimpact of the deficiency of any
developmental and behavioural impairments, hence it
nutrient on brain development is determined by the pe-
can influence motor and cognitive skills and the children
affected will present with the following:
riod in which the deficiency occurs, its degree and dura-
The specific influence of the deficiency of a
given nutrient depends on the physiological processes in
individual parts of the brain in which the nutrient par-
Short attention span
ticipates, and is manifested as a neurological function
Loss of alertness
disorder in that specific area. The blood-brain barrier
Loss of interest in the surrounding
provides an effective regulatory point for iron movement
the human nervous system. Ferritin moves from the
Poor school performance
plasma pool to the cerebral and spinal fluid, and from
the choroid plexus it moves into and out of the brain.
These brain related deficiets will limit the child’s capac-
resonance imaging (MRI) has been used to
ity to learn hence impaired intellect in the short- and
map iron distribution in the brains of children and ado-
long-term. Subsequent therapeutic correction of the se-
highest concentrations are found in the
rum iron will not revert the brain function to normal. A
Globus pallidus, caudate nucleus, putamen and substan-
large number of children with attention deficeit hyperac-
tivity disorder (ADHD) are known to be mentally re-
tarded. The hallmark of this condition is short attention
Ferritin is essential for a number of enzymes involved in
span and lack of focus which consequently affect learn-
including tryptophan hy-
ing.ADHD has been associated with an imbalance in the
brain level of dopamine, a neurotransmitter which re-
(norepinephrine and dopamine). Iron is related to the
quires iron for its synthesis.
Serum or peripheral iron
activity of monoamine oxidase, an enzyme critical for
ADHD children is known to be normal but study has
proper rates of degradation of these neurotransmitters. In
reported reduced brain iron in the thalamic region as
addition, iron is a cofactor for ribonucleotide reductase,
measured by magnetic resonance imaging (MRI) in
and is essential for the functioning of a number of elec-
ADHD patients suggesting a role iron in the pathogene-
sis of this disease.
tron transfer reactions related to both lipid metabolism
and brain-energy metabolism. Irondeficiency therefore
affects myelinisation, monoamine neurotransmitter syn-
limited number of studies have been conducted to
thesis and hippocampus metabolism during infancy.
determine if iron deficiency during non-developmental
Reductions in speed (myelinisation), changes in motor
periods of life are associated with changes in behaviour,
cognition and brain function.
Studies in adolescents
(hippocampus) all bear witness to these influ-
who were iron deficient, but not anaemic, revealed al-
The hippocampus is part of the limbic
terations in cognitive functioning that could be attrib-
and plays important roles in the consolidation of infor-
uted to iron depletion but not anaemia. When specific
mation from short-term memory to
long-term memory ,
tests of attention were performed, iron-deficient anaemic
and in spatial memory that enables
adolescents performed less well than iron-sufficient
teens but these individuals did respond to iron therapy.
is initially processed and consolidated by the hippo-
campi before being stored in the cerebral cortex.
Impact of iron deficiency on childhood intelligence
is important for normal development of the brain
which is the seat of human memory. Iron deficiency
Conclusion and recommendation
during pregnancy and lactation causes irreversible dam-
age to foetal/neonatal brain development and function,
Iron-deficiency anaemia (and low serum iron) in preg-
which may be manifested as arrested cognitive and so-
nancy and childhood in developing countries is largely
The basal ganglia and hippocampus
related to under nutrition thus making this problem a
support a number of cognitive processes, including
high-priority topic and highlights the key role of primary
higher-order cognitive functions such as general intelli-
and secondary prevention. Studies have shown that iron-
deficiency anaemia in pregnancy creates a significant
risk of reducing foetal iron storage thus causing cerebral
dysfunction to occur in utero. Even if the iron defi-
Knowledge is a familiarity, awareness, or understanding
someone or something, such as facts, information,
ciency is corrected after birth, their brain function may
descriptions, or skills, which is acquired through experi-
never be fully restored. Furthermore, the amount of iron
the mother’s milk is not usually sufficient to satisfy
iron deficiency, a nutritional problem that can be pre-
vented, or treated.
infant’s iron needs after the first six months of exclu-
such as intrauterine growth restriction and gestational
sive breast feeding during the first year. Iron supple-
ments for breastfeeding mothers has not produced satis-
increase the risk of iron defi-
factory results once the damage has already been done.
ciency in the late foetal and early neonatal period.
This highlights the importance of preventing iron defi-
ciency among women during pregnancy and breastfeed-
view of all these, the routine programme of iron sup-
ing. It is also important to adopt some other preventive
plementation to every pregnant woman should be under-
measures to cover infants especially during the first two
taken with a greater level of seriousness especially in the
years of life when brain growth is most rapid. The brain
developing world countries. There is also the general
formed from the third week of intrauterine of life; its
recommendation that iron should be administered to all
metabolism and volume continue to increase from birth
breastfed infants after the sixth month, and to all prema-
the age of five years a normal child
turely born infants and infants born with low birth
attains 90 per cent of his brain growth.
weight after the second month.
Additionally, serial capillary haemoglobin check-ups at
The WHO estimates that more than 30 per cent of preg-
well-baby clinics, is recommended. In areas where
nant women in developing countries has iron-deficiency
hookworm infestation is rife, heath education on envi-
anaemia and one in 4 to 5 babies develop iron deficiency
ronmental sanitation is mandatory plus regular deworm-
Anaemia is only a late manifestation of
ing programme partly towards preserving young brains.
iron deficiency, and iron deficiency without anaemia is
subtle effects of iron deficiency in
infancy lay the ground for later problems in cognitive
Conflict of interest: None
and behavioural functioning, then a large unrecognised
population of children may be at risk due to perinatal
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