Scientific Abstract from:
Sally Rogers, Ph.D.
University of California at Davis
Definition and Development of the Phenotype of Autism
This program of research will continue its dual foci: (1) defining the phenotype of autism at multiple levels of analysis; and (2) defining the continuities and discontinuities in the developmental course of autism using comparative longitudinal studies. In our first five years of funding, we were able to eliminate or refine four of the competing neuropsychological explanations of autism: a basic sensory deficit, a praxis deficit, a cognitive intersubjectivity deficit, and an executive deficit. Our past work has narrowed and deepened our focus to four key areas: 1) imitation and motor function, 2) core affective processes, 3) spatial working memory, and 4) relationships of brain structure and language functioning. In the proposed studies, we will examine these areas in autism at multiple levels of analysis. We will conduct longitudinal studies comparing autism, fragile X syndrome, Down syndrome, other developmental delays, and typical development across ages spanning from early infancy (through the use of home videos) to middle childhood, and will also include familial data from parents. Research methods will include behavioral and neuropsychological measures of children and family members.
The main aims of this project are to:
- Refine and delineate autism-specific impairments, and spared abilities;
- Examine whether skills in these areas are independent or whether relationships among them exist concurrently and longitudinally;
- Examine developmental and neuropsychological aspects of early regression;
- Determine whether the patterns of deficits are more suggestive of homogeneity or heterogeneity (suggesting potential subtypes); and
- Participate in cross-network projects that examine the biological, neuropsychological, and behavioral aspects of autism.
Principal Investigator: Sally Rogers, PhD
Imitation is a key mechanism for cultural transmission of skills and knowledge, serving an apprenticeship, or learning function. Imitation of others also serves a social function, permeating social and emotional exchanges, providing a key mechanism for emotional synchrony and communication between social partners, beginning in early infancy and continuing throughout the lifespan. Difficulty imitating others is one of the earliest behaviors that discriminates autism, across the lifespan, and imitation ability is closely related to the severity of core social symptoms of autism: to play skills and to language development. Yet the mechanisms underlying the imitation problems in autism have not yet been defined. The proposed study will examine the performance of 20 2-3 year olds with nonregressive autism, 20 with regressive autism, 20 with other developmental disorders, and 20 typically developing children at two time points using a series of experimental manipulations to explore two aspects of imitation: the apprenticeship function, involving instrumental motor acts on objects, and relationships with social responsivity. Aim 1 will examine the instrumental and motoric aspects of imitation. Hypothesis: oral-facial and vocal imitation, but not instrumental manual movements, will be specifically impaired in children with autism compared to controls.
Aim 2 will test directionality of the relationship between imitation and social responsivity. Hypothesis: children with autism and controls will show increased emotional responsivity to adult emotional displays following an imitative interaction in comparison to a non-imitative interaction. Aim 3 will focus longitudinally on developmental patterns of imitation and the relationships between early imitation skills and outcomes in autism across the early childhood period. Hypotheses: (1) Developmental sequences of facial and vocal imitation skills, but not instrumental manual skills, will be both delayed and disordered in autism compared to controls; (2) early imitation skills, particularly oral-motor imitation, will be a stronger predictor than early social-emotional responsivity of later speech development and social outcomes in autism.
Principal Investigator: Sally Ozonoff, PhD
Co-Investigators: Sally Rogers, PhD, and Isaac Pessah
The onset of autism occurs at two peak periods. Approximately 2/3 of children with autism display developmental abnormalities within the first year of life, while the other third display a period of mostly normal development, followed by a loss of skills and onset of autism. This Project examines the measurement, predictors, course, causes, and external validity of regression. Four studies compare children with regressive autism to those with early onset autism, non-autistic developmental delays, and typical development, providing a multi-level analysis of the regression phenomenon. Study 1 examines the validity of parent report definitions of regression. All previous studies of regression have employed parent report methods, yet their accuracy is not clear. Parent report measures of regression will be compared to videotapes from the first year of life, analyzed by trained researchers blind to diagnosis using a well-validated coding system of early social-communicative behavior. Study 2 will identify early warning signs of regression. Behaviors from the infant videotapes of children with later regression will be compared to children with typical development and developmental delay to identify early predictors of later regression. Study 3 examines potential causes of regression, including both familial and environmental factors. The potential role of exposure to metals with known neurotoxicity (e.g., mercury), environmental pollutants with suspected neurodevelopmental effects (e.g., PCBs), and immunologic abnormalities (e.g., auto-antigens to brain or other tissue) will be assessed, using specific biological assays, in all 4 groups. Study 4 tests the discriminant validity of regression from early onset autism, using a comprehensive age-appropriate neuropsychological battery that includes tests of all the major domains affected in early autism. These studies will lead to a better understanding of the neurobiological mechanisms underlying both regressive and early-onset autism, phenomenological differences between the two, earlier identification of at-risk children, with concomitant earlier intervention, and perhaps in the future, prevention of regression.
Project III: A Longitudinal Study of the Developing Phenotype of Autism
Principal Investigator: Susan Hepburn
Autism is a pervasive developmental disorder involving significant impairments in social and communicative functioning and restricted activities and interests (APA, 1994). Prospective longitudinal studies are uncommon and, yet, are critical to understanding the developmental course of the disorder.
We propose to continue a prospective, longitudinal study of the developing phenotype of autism from toddlerhood to middle childhood that: (1) begins at the earliest age at which diagnosis is possible, (2) uses standardized measures for diagnosis, (3) provides multiple measures of specific developmental processes over time and (4) incorporates several clearly defined control groups. The proposed study is a continuation of an existing study that includes 135 toddlers (32 with autism, 25 with Down syndrome, 28 with fragile X syndrome, 25 with mixed etiology developmental delay, and 25 typically-developing children). There are three waves of data collection (ages 2,4, and 8) with the goal of examining how various developmental processes interact and influence symptom development. Key areas of interest include: cognitive and language functioning, symptom presentation, affective functioning, intersubjectivity, imitation and praxis, executive function, temperament, problem behavior, and sensory reactivity. Hypotheses regarding rate (i.e., the timing of the emergence of a specific deficit within a specific group), structure (i.e., the characteristic developmental progression of specific skills in a specific group), concurrent processes (i.e., influences of specific deficits on the development of other skills), and developmental precursors (i.e., determining whether specific skills are necessary and/or sufficient for the development of other skills) will be tested. Analyses will be conducted on both intra-individual and inter-individual level, in order to examine universality, specificity, persistence, and precedence of each domain.