Parents, you may be onto
something: A small new study suggests that teens'
intelligence, as measured by the IQ test, may
fluctuate throughout adolescence.
The changes -- in both verbal and nonverbal IQ
-- ranged to as much as 20 points and were
correlated with specific brain areas.
IQ has long been thought to
remain stable over a person's lifetime. The findings
are published online Oct. 19 in the journal Nature.
The new findings might have
implications for kids' educations, the researchers
said, because they suggest that children, especially
those with lower IQs, should not be pigeonholed into
specific educational and career trajectories based
on their IQ alone.
"Approximately one-fifth of
our sample had very substantial changes such that
they moved from above average to below average or
vice versa," said Cathy Price, senior study author
and professor at the Wellcome Trust Centre for
University College London, U.K.
take-home message, according to one expert,
is that intelligence may not be as "fixed" in
adolescence as once thought.
According to the study
authors, prior studies have shown changes in IQ in
individuals over time, but those studies hadn't been
able to rule out the possibility of chance.
In their research, Price and
her colleagues measured the IQs of 33 individuals
aged 12 to 16 in 2004. They performed
MRI brain imaging of the adolescents' brains at
the same time.
Four years later, the same
group of individuals, now between 15 and 20 years
old, were tested and underwent additional MRI scans.
From Average to Gifted...
The team report that changes in IQ did seem to
occur, with some participants improving their scores
by as much as 20 points over time, relative to
people of similar age, while other kids saw declines
in IQ levels.
"A change in 20 points is a
huge difference," Price said in a statement to the
media. For example, she said, "if an individual
moved from an IQ of 110 to an IQ of 130 they move
from being 'average' to 'gifted.' And if they moved
from 104 to 84 they move from being high average to
According to Price, that
could have implications for adolescents' education,
since it suggests that intellectual ability changes
The fluctuations seemed
correlated to changes in certain brain areas, with
verbal IQ (such as might be used in language and
math) corresponding to a different part of the brain
than nonverbal changes (involving visual questions).
In the media statement, Price
explained that "the degree to which verbal IQ
changed correlated with the degree to which brain
structure changed in an area of the brain that we
are referring to as a 'motor speech area.' " She
added that this region, the brain's left motor
cortex, "is very active when we (including the
participants in our study) articulate speech."
correlated to changes in the anterior cerebellum,
which is also activated when making hand movements,
The authors don't know yet
what is driving these variations in IQ over time.
"It could either be an active environmental
effect (such as education/learning ) or it could
relate to developmental differences (late
developers/early developers) or it could be both,"
Price said in an interview. "This is the classic
nature/nurture debate. I am pretty sure that there
is a strong environmental effect because we know
that the adult brain changes with learning. In this
case, intensive training causes brain changes."
The take-home message,
according to one expert, is that intelligence may
not be as "fixed" in adolescence as once thought.
"The brain is clearly, at
least in the teenage years, more plastic and
amenable to change," said Paul Sanberg,
distinguished professor of neurosurgery and director
of the University of South Florida Center for Aging
and Brain Repair in Tampa. "The real question is,
does this continue into adulthood? Is this
reflective of changes we now see in plasticity in
the brain in adulthood? The data is suggesting that
things can get better."
It's not just for young
Price hasn't yet measured whether or not IQ changes
in adults, "but my guess would be yes, because
intensive skill training in adults causes brain
However, another expert
cautioned that the study did have some limitations.
Michael Carey is an assistant professor of
psychiatry and behavioral science at Texas A&M
Health Science Center College of Medicine.
He believes that some of the
IQ tests used in the study were outdated, nor did
they take into account other factors, such as age,
gender or whether a person is right-handed or
left-handed when identifying brain structures
related to the change.
"It's a relatively small
sample and pretty selective. The average IQs are
above average, even though there's a lot of
variation," said Carey, who is also a psychologist
with Scott & White, in Temple. "The question is, how
representative is this of natural day-to-day
By Amanda Gardner, HealthDay
On the Web:
www.nimh.nih.gov/media/video/giedd.shtml, the U.S.
National Institute of Mental Health has more on the