MadSci Network: Neuroscience

Re: Can scientists change the brain around to increase a human's intelligence?

Date: Fri Nov 12 16:01:11 1999
Posted By: joshua rodefer, Research Fellow in Psychobiology & Lecturer
Area of science: Neuroscience
ID: 941039606.Ns

Hi Andy!

Glad to have a question from Minnesota!  I did my graduate work at "the U" 
(U of Minnesota) and thus have many good memories about the area (and one 
of my best friends lives in Edina too). Now, on to the real reason you 
wrote.  You ask a timely question.  Increasing a person's intelligence is 
perhaps one of the most sought after goals in all of science.  Almost 
everyone has probably wanted to be a little bit smarter at some point in 
time - either to do better in school, or to answer those standardized test 
questions better, or just to be able to understand things more completely. 
But can we actually do anything about it?

Well, no and yes.  

To begin with, you need to think about what we mean by intelligence.  
Nowadays, intelligence is usually taken to be some form of test performance 
- sometimes on an IQ test or some other standardized testing procedure.  
There are many people who believe this is a flawed way to get at 
intelligence.  For instance, can one type of test measure intelligence and 
boil it down to some number?  Many people believe there are types of 
intelligence that are difficult to measure in a regular test format (like 
"street smarts" or social intelligence).  Another potential problem is that 
of cultural differences.  Can a test constructed by researchers in the USA 
accurately assess the intelligence of people who have been raised in 
different countries and cultures?  This last issue has really created a 
firestorm of controversy as there appear to be racial differences 
(Asian-Americans, European-Americans, African-Americans) on many types of 
standardized tests (like IQ and the SAT).  However, whether these are 
meaningful differences is an entirely different question.

The second thing you need to know is that how  "intelligent" you are 
(according to these types of tests) does change over time.  This is because 
each score is often a ratio of how well a person does divided by how well 
they should do according to their age or maturity.  So it is possible for 
someone to get "less smart" as they get older if they performed really well 
when they were younger.  In reality they would not be less smart - they 
were just advanced for their age when they were younger.  Likewise, if 
someone is a late bloomer, they may seem less smart at one point in time 
and then appear to get smarter.  This might also happen if something 
changed in your environment (example: going from a not-so-good school to a 
better school) that might impact how well you tested.

But can we make people smarter?

There are two parts to this question.  The first is getting at whether 
there are "smart" genes in our DNA.  The Human Genome Project is nearing 
conclusion - and the main goal is to sequence, or read, all of the DNA that 
we have in our cells to determine which genes control what behaviors.  Of 
course, the one very important behavior many people are interested in is 
intelligence.  Having "smart" genes may not make sense - but if you 
consider that intelligence is a trait just like eye color or height, then 
it does makes sense.  If there are genes for eye color (and there are!) 
then there probably are genes for intelligence (or something like 
intelligence).  For many years, researchers have known about genetic 
differences in intelligence by studying twins.  You probably remember from 
your biology classes that there are 2 types of twins: identical (or 
monozygotic; developing from one fertilized egg) and fraternal (or 
dizygotic; where 2 eggs get fertilized and develop at the same time).  
Identical twins share all the same genes, whereas fraternal twins are 
basically just like brothers/sisters who share the same birthday.  Now the 
trick is to compare identical and fraternal twins.  The reason to do this 
is that we know how much of their genetic material they have in common 
(identical twins share all, or 100%, whereas fraternal twins only share 
about 50% of the same genes). 

What researchers have found is that identical twins usually perform nearly 
the same on many types of IQ tests.  Fraternal twins on the other hand, do 
not score the same as each other. Why do the fraternal twins score 
differently than each other?   Since they are a set of twins, we know that 
they have been through many of the same experiences.  So the environment is 
the same (or pretty close) for each twin.   So the only real difference 
between the fraternal twins is their genes.  Thus we conclude there must be 
some genetic influence at work.

The second part is whether we can make people smarter - by doing something 
to them - perhaps making them take a class, or maybe by giving them a smart 
pill.  You no doubt have experienced the "practice-makes-perfect" analogy 
that parents and teachers always tell us.  It is true - practicing 
something (reading, writing, throwing a frisbee, playing the piano) does 
make you better at it - but does it make you smarter?  Probably not.  You 
most likely are just improving your performance.  Some people take classes 
to help them do better on some types of college-entrance tests (like the 
SAT).  Many college students take classes to help them do better on the 
tests that are required to get into medical (MCAT) or law school (LSAT).  
But does taking these special classes make them smarter or more 
intelligent?  No.  It is more likely that they are improving their 
abilities to take the tests - such as improving their time management 
skills, learning better ways to approach a type of difficult question, or 
easier ways to recognize potential wrong answers.    Recently there was a 
lot of attention given to a study that examined the effect of playing music 
by Mozart to children.  The original study reported that listening to 
Mozart increased the intelligence of the children.  So everyone went out 
and started buying Mozart CDs to play for their kids.  However, a very 
recent re-analysis of this Mozart-effect has shown that the children DO NOT 
display greater intelligence (see link below).

But can we give people a smart pill and see improvement in their 
intelligence?  Maybe!  There is a growing amount of evidence that there are 
certain types of drugs that improve learning and memory.  Most of these 
types of drugs improve the actions of a neurotransmitter in our brain 
called acetylcholine (or ACh for short; neurotransmitters are the chemical 
signals that our neurons use to tell other neurons to do something).  Some 
drugs seem to work through the ACh system to improve our vigilance (or how 
well we pay attention to details), while others seem to improve our 
abilities to do certain tasks (like pressing a button when you hear a 
certain sound).  

To make a long story short, yes we can give certain drugs and see some 
improvement - but usually it is an improvement in performance - not 
intelligence.  Moreover, usually these improvements only happen over the 
short term.  If you continue to take the drug you won't continue to see 
more improvement - in fact, you often will develop worse performance.  So, 
right now, no we can't really improve our intelligence.  But 25 years from 
now (when maybe you have children, or when you are researching this 
question) the answer might be different!

Thanks for a great question. I hope this helps shed some light 
on the issue for you.

Josh Rodefer, Ph.D.
Harvard Medical School


The I.Q. gene? Time magazine cover story from Sept 13, 1999

The Mozart Effect

Mozart Effect Hits Sour Notes (Harvard newspaper article)

Kaplan Test Preparation Courses

International Society for Twin Studies

Performance Enhancing Drugs and Athletics, by Jennifer Wolff

Article in JAMA about the drug Mark McGwire was taking

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