New Method Of Scoring IQ Tests Benefits Children With Intellectual Disabilities

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New Method Of Scoring IQ Tests Benefits Children With Intellectual

Disabilities

ScienceDaily (Dec. 15, 2008) —

Parents of children with intellectual disabilities have long been frustrated by

intelligence quotient (IQ) testing that tells them little to nothing about the

long-term learning potential of their children.

That's because these tests are scored according to the mean performance of

children without disabilities. The result is that the raw scores of many

children with intellectual disabilities are converted into the lowest

normalized score, typically a zero.

" We send back these reports that don't tell parents anything about

their child, " explained Hessl, an associate professor of clinical

psychiatry and a researcher at the UC M.I.N.D. Institute.

Hessl and a team of collaborators have devised a new system of scoring IQ

tests taken by children with fragile X syndrome, a genetic disorder that causes

intellectual disabilities, including autism. The details of the new method are

described in a study published online today by the Journal of Neurodevelopmental

Disorders.

" If this new method becomes widely available, we will be able to tell

parents something more useful and more accurately diagnose and treat young

children who are learning disabled, " said Hessl, a physician who cares for

children at the M.I.N.D. Institute with fragile X syndrome.

According to Hessl, there is a lot of meaningful variability in the

performance of these children on IQ tests.

" We believe that this variability is important information about the

relative strengths and weaknesses that these children have, " Hessl

explained. Frustrated by the lack of sensitivity of IQ tests, Hessl set out to

devise a scoring method that would reveal the strengths and weaknesses of each

child.

" I knew a more accurate estimation of the potential of these children

would make a big difference in their lives, " he said.

Hessl worked with fragile X researchers at the M.I.N.D. Institute and

Stanford University, as well as a statistician from Pennsylvania State

University. The team came up with new normalized scores for 217 children with

fragile X syndrome who had undergone IQ testing.

Many of these children had normalized scores of 0 on the Wechsler

Intelligence Scale for Children, an intelligence test for children between the

ages of 6 and 16 that can be completed without reading or writing.

On the new scale, children scored as low as minus 10 on 14 subtests. These

included verbal, arithmetic, picture completion and object assembly.

Like normalized scores of children without disabilities, the frequency of

the new normalized scores for children with fragile X syndrome followed an

expected, bell-shaped distribution.

" These new scores tell us more precisely how a child with fragile x

syndrome deviates from the normal population in every sub-test area, " Hessl

said.

Physicians and parents also need to know that these new scores reflect

something about the biology of the children.

So, the research team went on to compare the new normalized scores to a

measure of adaptive behavior and a biological measure of the severity of

fragile X syndrome. Without a normal copy of the fragile X gene, a vital

protein (FMR1 protein, or FMRP) is not made and the result is the onset of

characteristic mental disorders, which can range from learning disabilities to

severe cognitive or intellectual disabilities, such as autism.

Hessl and his colleagues compared the levels of FMRP in blood from the test

subjects to their new scores and found a significant correlation. They found

similarly significant correlations between the IQ test scores and scores on the

Vineland Adaptive Behavior Composite, which measures personal and social skills

used in everyday living.

Treatment of fragile X syndrome depends on its manifestations in the

individual, and range from behavioral therapy to medication. Widespread use of

new normalized scores would allow physicians to better treat their patients,

Hessl said.

Psychological Corporation, the publishers of the Wexler IQ test, gave

permission for their raw date to be used in the context of research.

" I think we've made a good case for the makers of this test and others

to release raw data to researchers so that this method can be applied to other

populations with intellectual disabilities, " Hessl said.

He is also hopeful that someday soon he will get permission to use his new

scoring method when treating his patients. In the future, the publishers of IQ

tests should include lower-functioning individuals in their standardization

studies, Hessl said.

" This might mean over-sampling those with intellectual disability in

order to get more sensitivity, but it would help so many children, " he

said.

Additional UC researchers include M.I.N.D. Institute medical director

Randi Hagerman; M.I.N.D Institute researcher Schneider; biochemistry and

molecular medicine associate researcher Flora Tassone; and Danh Nguyen,

associate adjunct professor of public health sciences. Other investigators

included Damla Senturk of Pennsylvania State University, and Amy Lightbody,

Allan Reiss and Hall, all of Stanford University.

Journal reference:

1. Hessl

et al. A solution to

limitations of cognitive testing in children with intellectual disabilities:

the case of fragile X syndrome. Journal of Neurodevelopmental Disorders,

2008; DOI: 10.1007/s11-8

2. http://www.sciencedaily.com/releases/2008/12/081215112701.htm