Dyscalculia – is it chronic? Findings from an Israeli long term study

  

Developmental dyscalculia: a prospective six-year follow-up

Ruth S Shalev, Orly Manor and  Varda Gross-Tsur.  

Developmental Medicine & Child Neurology 2005, 47: 121–125

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8749.2005.tb01100.x/pdf

Prof. Ruth Shalev, Prof. Varda Gross-Tsur  and Dr. Orly Manor followed, for six years, in a wide scope study, a group of children diagnosed with dyscalculia.

How were the children recruited?

In fourth grade, about 3000 children studying in Jerusalem schools took a group arithmetic test.  550 out of the 600 children whose scores were in the low 20% took, in fifth grade, an individually administered arithmetic test.  140 children out of this group scored in or below the 5^th percentile in the arithmetic test and had a WISC-R IQ score above 80.  This group was diagnosed with dyscalculia.  The reading and writing skills of these140 children were assessed,  and they were given other cognitive tests as well (which I'll not go into here for sake of brevity).

After three years, when they were in 8^th grade, 123 children out of this group took a math test and a reading test again.  The math test scores of 95% of the children were in the 25^th percentile or below.  47% of these children were re-diagnosed with dyscalculia, having scored in the 5^th percentile or below.

After three more years, when they were in 11^th grade, 104 of these children took math, reading and writing tests again and were compared to a control group.

What were the findings?

The authors emphasize the performance of the dyscalculia group, but I think it's worthwhile to look also at the control group's performance.

Let's begin with four examples:

·         51% of the 104 11^th grade students identified in 5^th grade with dyscalculia  were not able to solve 8x7, compared to 17% of the control group.

·         71% of the 104 students were not able to solve 24x37, compared to 27% of the control group.

·         49% of the 104 students were not able to solve 45/3 compared to 15% of the control group.

·         63% of the 104 students were not able to solve 5/9+2/9, compared to 17% of the control group.

And in general:

40% of the 104 students scored in or below the 5^th percentile, and were re- diagnosed  with dyscalculia.

The authors point out that the scores of most remaining 60% of children was still "low" – in and under the 25^th percentile.  Since every score which is higher than the 16^th percentile is within one standard deviation below the mean, we can regard such scores as normal performance (even if not high).   The authors don't indicate what percentage of the 104 children had a score higher than the 16^th percentile.

Which 5^th grade measures were related to dyscalculia in 11^th grade?

The 5^th grade general IQ score, calculated without the arithmetic subtest, was in average 6 points lower in the 104 student group than in the control group.  The 104 student group also had more inattention and writing difficulties than the control group.

Which 5^th grade measures were NOT related to dyscalculia in 11^th grade?

Reading, word learning, fluency tests, face recognition and performance in RCFT test were not related to dyscalculia in 11^th grade. 

Educational interventions, socioeconomic status, parental education, gender and family history of learning difficulties were not related to dyscalculia in 11^th grade.

What do we learn from all this?

Apparently, dyscalculia as defined here (a score in or below the 5^th percentile in an arithmetic test and an IQ score within normal limits) is chronic in 40% of the cases.  Had we defined dyscalculia as a score in or below the 16^th percentile in an arithmetic test and an IQ score within normal limits, probably a higher percentage of the 104 student group would have been diagnosed with chronic dyscalculia.

Nevertheless, there were some children in this study who made progress and moved from performance in or below the 5^th percentile in 5^th grade, to performance of above the 16^th percentile in 11^th grade.  It's unclear what caused this improvement.  This is a question worth studying.  We can also hope, that early assessment, much earlier than 5^th grade, maybe even in preschool, and preventive intervention,  will make it possible to prevent the development of dyscalculia in at least some of the children.