Objective: To study the natural history of developmental dyscalculia (DC), a specific learning disability affecting approximately 5% of the normal school age population and to identify factors that contribute to persistence.
Study design: Of a cohort of 3029 fourth-grade students, 185 children were classified as having DC; 140 participated in phase 1 in which they underwent IQ testing; arithmetic, reading, and writing evaluations; and an assessment for attention-deficit/hyperactivity disorder over a 3-year period. Three years later (phase 2), 88% of the children (123 of 140) were retested.
Results: The arithmetic scores of 95% of the 123 children with DC fell within the lowest quartile for their class. At phase 2, 47% (57 of 123) of the children were reclassified as having persistent DC, scoring in the lowest 5% for their age group (13 to 14 years old). Factors significantly associated with persistence of DC in a multivariate model were severity of the arithmetic disorder and arithmetic problems in siblings of the probands. Factors that were not associated with persistence included socioeconomic status, gender, the presence of another learning disability, and educational interventions.
Conclusions: The outcome of DC is similar to that of other learning disabilities, with a persisting course in almost half of affected children; the remainder continue to perform poorly in arithmetic. The ultimate outcome of children with dyscalculia and the effect on education, employment, and psychologic well-being have yet to be determined.