Colligan, Robert C.

OBJECTIVE. The aim of this study was to report the incidence rates and other epidemiologic characterizations of written-language disorder. There have been no epidemiologic studies on the incidence of written-language disorder in the United States, and the use of a population-based birth cohort, longitudinally followed, is the most powerful method for reaching this objective.METHODS. In this population-based, retrospective birth cohort study, subjects included 5718 children born between 1976 and 1982 in Rochester, Minnesota, who remained in the community after 5 years of age. Records from all public and nonpublic schools, medical facilities, and private tutorial services were reviewed and results of all individually administered IQ and achievement tests, and extensive medical, educational, and socioeconomic information, were collected. The essential features of writing problems from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision were included in our operationalized definition of written-language disorder. Written-language disorder incident cases were established by using research criteria based on 3 formulas (regression-based discrepancy, nonregression-based discrepancy, and low achievement).RESULTS. Cumulative incidence rates of written-language disorder varied from 6.9% to 14.7% depending on the formula. Boys were 2 to 3 times more likely to be affected than girls regardless of the formula. Among all written-language disorder cases (N = 806), 25% (n = 203) had written-language disorder without a reading disability. Specifics of the writing problems were identified for 87% (n = 702) of written-language disorder cases.CONCLUSIONS. In this population-based birth cohort of school-aged children, written-language disorder was at least as frequent as reading disabilities and significantly more frequent among boys than girls.

Based on the postulate that there is a continuum of reproductive casualty, it was hypothesized that potentially stressful perinatal experiences would subsequently produce measurable effects on certain psychologic tests in the children studied. Prospectively gathered data from 386 neurologically normal 7-year-old children were reviewed, and a perinatal stress score was derived for each by a simple count of deviant symptoms during pregnancy, delivery, and puerperium. Results marginally supported the concept of continuum of reproductive casualty but were neither clear nor systematic. The perinatal stress score may have been contaminated with items of little or no significance, which would have decreased its discriminating power.

The Minnesota Child Development Inventory (MCDI) was used to describe the developmental status of 59 children before the start of kindergarten. Three years later children were classified in one of four categories, based on the amount of supplemental reading instruction necessary during the three-year period. A number of variables from the MCDI were highly correlated with this continuum of difficulty in mastering reading, with parental report of the child's general development and knowledge of letters and numbers being most significant. Significant correlations with group achievement tests also were obtained. The findings should encourage the inclusion of parent reports by persons using or constructing preschool screening measures.