Familial aggregation of phonological disorders: results from a 28-year follow-up.

This investigation is a follow-up to a longitudinal speech and educational outcome study involving approximately 400 normally developing children that was initiated in 1960. From this database, two groups of subjects (now aged 32-34), their spouses, and all of their offspring over the age of 3:0 (years:months) completed a battery of cognitive-linguistic and interview measures. One group (probands) consisted of 24 adults with a documented history of a moderate phonological-language disorder that persisted through at least the end of the first grade. The other group (controls) consisted of 28 adults who were known to have had normal articulation abilities as children. Results of this study demonstrated that, in comparison to the children of controls, the children of the proband subjects performed significantly more poorly on all tests of articulation and expressive language functioning and were significantly more likely to have received articulation treatment. There was, however, no evidence that specific misarticulations or phonological processes traveled within proband families. These results are in agreement with those of most previous family studies that have demonstrated an increased rate of occurrence of speech-language disorders of unknown origin in families including a first-degree relative who is similarly affected.