Dyslexia v Dyscalculia: Maths v Reading

One of the important areas for understanding learning disorders is learning about the prevalence and specificity of various types of disorders.

It is estimated that Dyscalculia, the maths disorder or disability, is present in about 7% of school children.

It is possible that Dyscalculia simply represents a component of a more general learning disability.

If this is true, there should be a large overlap between Dyscalculia and other learning disorders, such as Dyslexia, the reading disorder.

A well-designed longitudinal study of cognitive and academic ability from Donald Compton and colleagues at Vanderbilt University is information in addressing this issue.

They completed a longitudinal study of 684 students from 3rd grade through the 5th grade assessing four academic achievement domains:

• reading comprehension
• word reading
• applied math problems
• math calculation skills

Additionally, they examined five student cognitive skills including: non-verbal problem solving, processing speed, concept formation, language and working memory.

The key finding from their study is that Dyscalculia in general terms, appears to be a specific disorder.

Although 3.8% of their school children sample had both Dyslexia (reading disorder) and Dyscalculia (math /calculations disorder), 10.1% were estimated to have only Dyscalculia and 6.6% were estimated to have only Dyslexia.

They noted their "results indicate that, although co-morbidity (the co-existance of Dyslexia and Dyscalculia together in one person) does occur, it is limited to approximately 20% of student with learning disability. This adds credence to the notion that reading and mathematics learning disability may be distinct and separate".

Background
Differences between Dyscalculia and Dyslexia included the following:

• Boys had higher rates of Dyslexia, reading comprehension learning disability, while Dyscalculia (math problem and calculation types) were found equally in boy and girl students
• Both Dyscalculia and Dyslexia rates were linked to student poverty status-students in the lowest socio-economic group had higher rates of both math and reading disorders.
• Both Dyscalculia and Dyslexia students showed relative strength in the processing speed cognitive domain

This study lends support to Dyscalculia being a specific type of learning disability that often occurs without Dyslexia as a co-occurring reading disorder.

Dyscalculia appears to be the most common learning disability in girl students.

Reference
Compton DL, Fuchs LS, Fuchs D, Lambert W, & Hamlett C (2012). The cognitive and academic profiles of reading and mathematics learning disabilities. Journal of learning disabilities, 45 (1), 79-95 PMID: 21444929