The Child Language Research Center began in 1993 when funding was awarded to Dr. Bruce Tomblin and his colleagues by the National Institute on Deafness and Other Communication Disorders. In the decade prior to this, a new term, Specific Language Impairment (SLI), had emerged to describe the condition that occurs when young children don't seem to acquire language skills that come easily to their peers. By 1993, the NIH was interested in learning more about the basic epidemiologic features of SLI.

Epidemiologic study: The NIDCD awarded a contract to Tomblin to determine the prevalence and risk factors for SLI. In collaboration with epidemiologists, a study was designed to sample a large number of children who were entering school and identify among them the children with SLI. In order to do this, it was first necessary to develop diagnostic standards and measurement tools to screen for SLI. This work was published in 1996 (Tomblin, Records, & Zhang, 1996). The study called for examining SLI within the context of children living in urban, suburban, and rural strata. Therefore, three areas of Iowa were targeted that contained cities of more than 100,000 people.

More than 7,000 Midwestern kindergartners were then sampled and screened for poor language. Nearly 2,000 were then given more extensive diagnostic tests for SLI. This resulted in a final study that reported the prevalence of SLI (Tomblin et al., 1997).

The team also collected social, economic and health information about many of these children's backgrounds to see what risk factors might be associated with SLI. These data revealed that most of the risk factors pertained to characteristics of the parents' backgrounds and behaviors (Tomblin, Smith, & Zhang, 1997).

While the SLI epidemiologic study added significantly to science's understanding of human language development, it also provided the opportunity to learn a great deal about SLI in a sample of children who represented a random sample of such children. Most research on clinical conditions employs people who are receiving clinical services. It is well known that such clinical samples are actually not representative of all those who have a given condition. A longitudinal study that examined how these children develop and what happens to these children was compelling.

Longitudinal study: In light of the value of a longitudinal study of SLI, the CLRC applied for and received NIDCD funds to follow these children. The longitudinal study sampled more than 600 children from the kindergarten study to follow. About half of these children were identified as having a language impairment, while the remaining half served as the control group.

Now in high school, the research group continues to collect data, and thus, final conclusions are cannot be made yet. However, Tomblin and his colleagues' suspicions about the pervasiveness of language difficulties seem to be well founded.

For example, investigators can predict - with 80 percent accuracy - that a child with oral language difficulties at kindergarten will show problems reading in second grade. Overall, academic development, especially in reading and writing, suffers in children with language difficulties.

Behavioral problems also seem to accompany SLI. These children are likely frustrated by the inability to communicate well, which in turn, can lead to behavior and discipline problems.

Genetic studies: Early in our research, one risk factor began to stand out. There seemed to be more speech, language, and reading problems in the families of children with SLI than in families of controls. These observations led to funded research projects that examined the extent to which this familial characteristic was due to genetic factors and how much was environmental. This work resulted in findings that, as in many cases, it was both (Tomblin & Buckwalter, 1998). The fact that genes may contribute to a child's predisposition for SLI resulted in our teaming up with Dr. Jeff Murray and his research team at Iowa's College of Medicine. We have used the children in the longitudinal study to determine if genes that are already known to influence learning are associated with SLI.

As we seek additional information, however, we realize the study of the genetic aspect of language development and disorders is complex. It appears that no one gene is responsible for language development. Rather, it is likely that several genes influence the development of language - and when non-genetic factors are added to the mix - the full picture of language development may take years to fully understand.

The CLRC team also collaborates with other researchers, including experts in the area of language of children with cochlear implants, reading disabilities, and other language development problems.

Until the language development is fully understood, however, parents can take a proactive role by frequently talking with and reading to their young children. This enrichment during a child's early years can only benefit an individual's language skills.

Reference List
Tomblin, J. B. & Buckwalter, P. (1998). The heritability of poor language achievement among twins. Journal of Speech and Hearing Research, 41, 188-199.

Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O'Brien, M. (1997). The prevalence of specific language impairment in kindergarten children. Journal of Speech Language Hearing Research., 40, 1245-1260.

Tomblin, J. B., Records, N. L., & Zhang, X. (1996). A system for the diagnosis of specific language impairment in kindergarten children. Journal of Speech & Hearing Research, 39, 1284-94.

Tomblin, J. B., Smith, E., & Zhang, X. (1997). Epidemiology of specific language impairment: Prenatal and perinatal risk factors. Journal of Communication Disorders, 30, 325-344.