Math learning disorder: incidence in a population-based birth cohort, 1976-82, Rochester, Minn.
OBJECTIVE
To report the incidence of math learning disorder (Math LD) among school-aged children, overall and by gender. To compare incidence estimates obtained by using three different methods to identify Math LD cases. To assess the extent to which children manifest Math LD alone, versus Math LD with comorbid reading disorder.


METHODS
This is a population-based, retrospective, birth cohort study. Subjects included all children born 1976-82 who remained in Rochester, Minn after age 5 (N = 5718). Using records from all public and private schools, medical facilities, and private tutorial services, all individually administered intelligence quotient and achievement tests and extensive medical, educational, and socioeconomic information were abstracted. Math LD was established using research criteria based on 3 formulas (regression-based discrepancy, nonregression-based discrepancy, low achievement).


RESULTS
Cumulative incidence rates of Math LD by age 19 years varied from 5.9% to 13.8% according to the formula used. Boys were more likely to be affected than girls, with relative risk ratios from 1.6 to 2.2 depending on the formula applied. Many children with Math LD (35% to 56.7%, depending on the formula used to define Math LD) did not have a comorbid reading disorder.


CONCLUSIONS
These results, from a community-based birth cohort, suggest that Math LD is common among schoolchildren, and is significantly more frequent among boys than girls, regardless of definition. Many children with Math LD do not have an associated reading disorder.
Barbaresi
William J
WJ
Department of Pediatric and Adolescent Medicine, Division of Developmental and Behavioral Pediatrics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. barbaresi.william@mayo.edu
Katusic
Slavica K
SK
Colligan
Robert C
RC
Weaver
Amy L
AL
Jacobsen
Steven J
SJ
D000293:Adolescent; D000328:Adult; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007859:Learning Disabilities / Q000453:epidemiology*; D008297:Male; D008433:Mathematics; D008910:Minnesota / Q000453:epidemiology; D017678:Sex Distribution