Group comparison data are summarized in (IQ), (CELF-III and PPVT), (CTOPP), and (WJ-R).
Performance on WISC-III (probands and siblings) and WAIS-III (parents)
Performance on CELF-III and PPVT
Group Comparisons - Probands
As expected based on our definition of the proband groups, ALI and SLI probands had comparable receptive, expressive, and total language scores on the CELF-III and non-word repetition scores, and both groups scored lower than ALN probands. ALI and SLI probands also performed similarly on verbal, performance, and full-scale IQ, lexical comprehension, phonological awareness and memory, broad reading, reading skill, dictation, and passage comprehension with scores in both groups lower than that of the ALN group. ALN probands scored similarly to ALI probands on rapid naming but better than SLI probands. There was no difference in rapid naming performance between ALI and SLI probands. Word attack scores were highest in the ALN probands and lowest in the SLI probands.
Group Comparisons – Family Members
Performance was highest in ALN relatives and lowest in SLI relatives (i.e. ALN > ALI > SLI) on the following measures: verbal and full-scale IQ, receptive and total language ability, and all measures of reading ability. ALN and ALI relatives performed similarly but significantly higher than SLI relatives (i.e. ALN = ALI > SLI) on the following measures: performance IQ, expressive language, lexical comprehension, and all measures of phonological processing. For performance IQ, a significant group by relationship interaction was obtained. Scores for ALN and ALI siblings were similar to one another but significantly higher than the scores of the SLI siblings. ALN fathers scored higher than SLI fathers but there were no significant group differences between ALN and ALI fathers or ALI and SLI fathers, and no group differences for mothers of all three groups. There were significant main effects of relationship for non-word repetition, phonological awareness, dictation, and passage comprehension. For non-word repetition, mothers and fathers scored similarly but poorer than siblings across groups. For phonological awareness and dictation, siblings and mothers scored similarly but higher than fathers across groups. For passage comprehension, siblings scored higher than fathers while there were no differences between siblings and mothers or mothers and fathers on this measure across groups.
Proportion of First-Degree Relatives Performing in the Normal and Language-Impaired Range
displays the number and percentage of first-degree relatives that performed in the normal or language-impaired range on total language ability or non-word repetition.
Proportion of First-Degree Relatives Performing in the Normal and Language-Impaired Range on CELF-III or Non-word Repetition
There were significant group differences in the proportion of siblings, mothers, and fathers performing in the language-impaired range on non-word repetition (mothers, fathers, and siblings) and CELF-III total language ability (siblings only). For siblings, this proportion was highest in the SLI group but was similar between ALN and ALI siblings. For mothers, this proportion was highest in the SLI group and lowest in the ALN group. For fathers, this proportion was significantly higher in the SLI group versus the ALN group; however, there was no group difference between ALN and ALI fathers or between ALI and SLI fathers.
Relationship of Language Abilities to ASD Severity
displays scatterplots of ADOS and ADI-R algorithm scores in the ALN and ALI probands. There were no group differences between ALN and ALI probands for the sum scores for the ADI-R (ALN Mean=47.37, S.D.=8.80; ALI Mean=46.72, S.D.=7.25; t(49)=0.29, p=0.78) or the ADOS (ALN Mean=14.75, S.D.=4.92; ALI Mean=14.84, S.D.=4.92; t(39)=0.06, p=0.95). There were also no significant correlations between total language ability on the CELF-III and the algorithm domain scores of the ADI-R or the ADOS across the ALN and ALI groups. There were no significant correlations between non-word repetition and the algorithm domains of the ADI-R. Only the social domain score on the ADOS was correlated with non-word repetition (r=0.36, p=0.02); however, this relationship did not maintain significance after a Bonferroni correction for multiple comparisons.
Figure 1 Scatterplots of algorithm scores for verbal communication (ADI COM), reciprocal social interaction (ADI SOC), repetitive behaviors and stereotyped patterns (ADI REP), and total sum (ADI SUM) on the ADI-R and communication (ADOS COM), reciprocal social (more ...)