exposure to allergy affects the brain development and functioning of offspring.
- The number and behavior of immune cells in the
developing brain of offspring were
found to be altered.
- The offspring
of allergic mothers were
hyperactive, but had lower levels of anxiety-like behavior.
- Males born to the allergen-exposed mothers were more socially reserved compared to females.
Allergies during pregnancy are linked to higher
risks for attention-deficit hyperactivity disorder
and autism in children.
The new study was
conducted by The Ohio State University and lead by
‘Treatment for autism and ADHD includes a combination of medication, psychotherapy and training to control symptoms and improve the quality of life.’
Kathryn Lenz, an assistant professor of
Her team found significant
changes in the brain make-up of fetuses
and newborn rats exposed to allergens during pregnancy.
Animals that lived to adulthood after allergen
exposure before birth showed signs of hyperactivity and antisocial behavior and
"This is evidence that prenatal exposure to
allergens alters brain development and function and that could be an
underappreciated factor in the development of neurodevelopmental disorders,"
said Lenz, who presented the research in
San Diego at Neuroscience 2016, the annual meeting of the
Society for Neuroscience.
There are established links
between allergies and attention-deficit hyperactivity disorder or ADHD and autism
as well as between inflammation and risk of autism, schizophrenia
But the cellular-level changes
that could contribute to those connections largely remain a mystery. The
researchers then set out to look for sex differences in the
rats as well.
"We're really interested in figuring out unknown
factors in psychological disorders and in differences between male and female
brain development as it relates to autism, ADHD and other disorders," Lenz
Exposing Pregnant Rats to Allergens
To study the effects of allergies on offspring,
researchers sensitized female rats to ovalbumin (found in egg whites) before
exposed them to the allergen 15 days into their pregnancies, prompting an immune response in the animals.
They analyzed whether prenatal allergen exposure
changed the number and behavior of immune cells in the developing brain of
They explored possible changes in young rats'
physical activity, anxiety-like behavior, ability to learn and sociability.
The researchers also examined
the density of dendritic spines in the juvenile animals' brains.
The spines protrude from neurons and are vital to
cellular-level communication in the brain.
Rats exposed to allergens before
birth had higher levels of immune cells called mast cells in the brain and
lower number of immune cells called microglia, regardless of the animals'
Rat offspring with allergic
mothers were hyperactive, but had lower levels of anxiety-like behavior.
The mental flexibility of rats born to allergic
mothers was also reduced.
Behavioral Differences in Male and Female Rat
When they interacted with other juvenile rats,
the males in the allergen group were less likely to be violent with their peers.
"Young rats engage in social play and males are
more rough and tumble and usually play much more than females," Lenz said.
But the males born to the
allergen-exposed mothers looked more like females.
They were more socially reserved
and disengaged but really hyperactive. They
displayed characteristics of ADHD.
The study shows that the dendritic
spines - the points of synaptic connection between cells in the frontal cortex
of the animals' brains, were
decreased in males with allergy exposure and increased in their female
"They have to use rules to find a reward - a
Cheerio in a terracotta pot - and the rules we give them keep shifting," Lenz
said, explaining that in one test the treat might be in a pot covered in
sandpaper and in another test it might be in a pot covered in velvet.
The rats in the allergen group were
not as capable of adapting to the changing parameters of the
test, and the males had deficits that were more significant than the females.
Attention-Deficit Hyperactivity Disorder
ADHD is a brain disorder characterized by an
ongoing pattern of hyperactivity-impulsivity and inattentiveness. It interferes
with daily functioning and development.
Some patients with ADHD have issues with only one
behavior while others have both hyperactivity-impulsivity and inattentiveness.
Among toddlers, hyperactivity is the most obvious
symptom of ADHD.
In people with ADHD
the behavioral symptoms occur more often, with more severity and interferes
with daily life activities and at social level.
A few risk factors that have been identified for
ADHD are genes, alcohol use, cigarette smoking, exposure to pollutants during
pregnancy and brain injury.
There is no cure for ADHD but the treatment
includes a combination of medication, psychotherapy and training to control
symptoms and improve the quality of life.
As of 2011, 11% or 6.4 million children between 4
to 17 years have been diagnosed with ADHD. The worldwide prevalence of ADHD
among children and adolescents is between 5.29% and 7.1% and in adults it is at
Autism is one of the many disorders that falls
under the autism spectrum disorder (ASD) group.
Though autism has its roots in very early brain
development, the obvious symptoms occur between the ages of 2-3 years.
ASD is characterized by intellectual disability,
poor attention, difficulty in motor coordination and physical symptoms like
sleep and gastrointestinal disturbances.
According to the US Centers for Disease control
and Prevention, one in 68 children in America fall under the autism spectrum.
Prevalence of autism has increased from 10% to 17% in the recent years.
One in 42 boys and one in 189 girls are diagnosed
with autism in the US.
Autism and ADHD
are both three to four times as common in boys
than in girls, Lenz said.
- Attention-deficit/hyperactivity disorder
- Epidemiology - (http://www.adhd-institute.com/burden-of-adhd/epidemiology/)
- What is Autism - (https://www.autismspeaks.org/what-autism)