Neuroimaging Genomics
by Jason McLeod, MBS 2021, Geisinger Commonwealth
School of Medicine
Mentor: Dr. Gregory Shanower, PhD
“Click, click, click...” I hear as I am lying in
the MRI scanner. It has been about twenty minutes,
and I am getting uncomfortable. “Try not to move.
You’re almost there!” the radiology
technologist says through the intercom. It can
take anywhere from 15-60 minutes for an MRI,
depending on the body region scanned. It takes a
lot longer than a CT scan; however, it
produces a clearer image of various organs and
tissues in the body. First, the MRI works by
introducing a magnetic field in and around the
scanner. Second, radio waves are introduced,
which cause water molecules in the body to
alternate their position briefly. The amount of
energy produced by this action is read by imaging
software that has the capability to translate it
into cross-sectional images. These images are
generally read by radiologists who interpret the
images in aiding in diagnosing a patient.
The MRI is beneficial in understanding one of the
most complex organs in our body, the brain.
Not only can an MRI image visualize individual
components of the brain, but it can also give an
estimation of overall brain thickness. Variations
in brain thickness have become an essential
factor in further understanding complex traits
and neurological disorders. Due to the recent
discovery that many traits and neurological
disorders have a genetic component, researchers
have decided to investigate if associations exist
between genetic variation and brain thickness
in these areas. The method of choice to employ
these investigations is the use of MRI imaging.
Brain MRIs of individuals with the neurological
disorder Schizophrenia often exhibit some
decrease in overall brain thickness. However,
many studies that have been replicated have not
been able to attribute Schizophrenia-associated
genetic variation to reductions in overall brain
thickness. Although, many studies examining this
relationship have concluded that other areas
of brain structure and volume are different in
individuals who do not have Schizophreniaassociated
genetic variation. Another neurological disorder,
attention deficit hyperactivity
disorder (ADHD), is often associated with
decreased overall brain thickness. Brain MRIs have
also shown a decrease in thickness in areas of
the brain, which helps with attention span,
decision making, and memory. This may explain why
individuals affected by ADHD can
experience difficulty in paying attention for
periods of time. ADHD is also found to be highly
genetic. Brain MRIs have identified decreases in
brain structure volume in individuals with
ADHD-associated genetic variation in recent
studies. However, when evaluating brain
thickness, these studies often have mixed
results.
The current research findings are exciting and
add to the hope that individuals affected by
neurological disorders will be provided with
better treatment options and know their risk of
developing a disease earlier than ever before.
However, genetics is not the only component in
complex traits or neurological disorders.
Environment plays a significant factor in many cases,
such in the case of intelligence. Intelligence,
summarized, is the ability to learn, comprehend,
and problem solve. Due to the complex nature of
intelligence, it is mediated by both genetics
and the environment. This does not guarantee that
highly intelligent parents will give birth to a
highly intelligent child. It supports the notion
that highly intelligent parents will foster an
environment that promotes the accumulation of
intelligence factors. Recent studies have
concluded that higher intelligence is shown to be
associated with an increase in overall brain
thickness through brain MRI. Yes, that means that
highly intelligent people generally have larger
brains. However, it is not as simple as that.
Many factors can affect brain thickness. Smoking,
medication use, and even aging alone causes brain
thickness to decrease over time. Many
studies have found ways to attempt to counteract
these factors, but what about the unknown?
The field of neuroimaging genomics is still very
recent. Future considerations for research in
neuroimaging genomics are to try and identify if
genetic variation is causing alterations in brain
structure or if disorders developed are mediating
these changes. One must consider that the
MRI is only a single snapshot in time. Although
cost is a concern, studies would benefit from
examining the long-term changes in study participants through,
possibly yearly, brain MRIs.
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