Date Approved

6-9-2008

Date Posted

12-15-2009

Degree Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department or School

Psychology

Committee Member

Renee Lajiness-O’Neill, Ph.D., Chair

Committee Member

James T. Todd, Ph.D.

Committee Member

Ellen Koch, Ph.D.

Committee Member

Bill Cupples, Ph.D.

Abstract

The primary goal of this investigation was to illuminate variables of the specific language impairment (SLI) and autism spectrum disorders (ASD) neuropsychological endophenotypes and to clarify the nature of overlap between SLI and ASD. Group differences in cognitive functioning, epidemiological factors including proband comorbidity and health problems, and familial data in 39 SLI children and 89 ASD children who presented for clinical evaluation at Henry Ford Health System in Detroit were examined by retrospective chart review.

Cognitive data revealed that ASD probands performed more poorly on tests of perceptual-motor functioning and had higher rates of pragmatic language deficits than SLI probands. In addition, ASD probands had higher rates of pragmatic speech problems than SLI probands.

Proband comorbidity and health problem group differences were noted in several areas. SLI probands had higher rates of learning disorders, asthma, and stomach/digestion problems than the ASD probands. ASD probands had higher rates of mental retardation (MR) than the SLI probands.

Familial group differences were noted in parental education levels and family history of psychopathology. SLI parents were less likely to have obtained a high school diploma or GED than ASD parents. SLI probands had higher rates of first-degree maternal relatives with learning disorders than ASD probands. ASD probands had higher rates of first-degree maternal relatives with ASD and thought disorders than SLI probands.

In addition to significant findings between the diagnostic groups, differences between severity levels were also found. The severe groups performed more poorly on tests of academic functioning and visual attention than mild-moderate groups. In addition, the severe groups had higher rates of verbal communication content problems than the mild-moderate groups.

In terms of comorbidity, the mild-moderate groups had higher rates of learning disorders and ADHD than the severe groups. The severe groups had higher MR rates than the mild-moderate groups. Finally, familial data indicated that the mild-moderate groups had higher rates of parents employed in business/finance and engineering/science than the severe groups.

Overall, these findings provide valuable information on factors present in SLI and ASD neuropsychological endophenotypes and increase understanding on the nature of overlap between the two disorders.

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