[Specific impaired language development: a selective or generalised cognition problem]

Specific developmental language disorder (SDLD) is a diagnostic entity in which language is expected to be the only cognitive function that is affected. Nevertheless, difficulties in other cognitive functions may also appear, either because the language disorder is an expression of an underlying condition or because the retarded language development gives rise to cognitive deficits in general.

To determine whether there are any differences in the cognitive performance of children with SDLD and that of children who have developed normally.

The study involved a sample of 51 children with SDLD, aged between 6 and 16 years, and 49 children in a control group, who were paired by chronological age, sex and socioeconomic level. Verbal cognitive capacity, attention, memory, visual-constructional and executive functioning were all evaluated.

Statistically and clinically significant differences were found in the verbal-type skills, such as language comprehension and verbal cognitive capacity, which showed effect sizes of -1.31 and -1.33, respectively. In the other functions that were assessed, the performance of the SDLD group was slightly lower than that of the control group, but with no clinically significant differences.

These findings show that the group of children with SDLD was well selected, since the only differences between the two groups involve linguistic aspects; moreover, this evidence supports the idea that language and other cognitive functions are relatively independent and that a language disorder would only generate an unspecific general effect in the other cognitive functions.