Eric Courchesne - US grants

Our proposed research will investigate the relationship between cognitive dysfunction in adolescents and adults with infantile autism and various components of the ERP (event-related brain potential) which are known to be associated with cognitive processes in normal adolescents and adults. ERPs will be recorded from non-retarded individuals with autism (ages 13 to 30 years) and from matched normal controls using an array of scalp EEG electrodes. The visual and auditory ERP components which are associated with attention, orienting, and memory modification will be compared between these subject groups. We will explore the possibilities that non-retarded autistic people differ from normal in their cognitive functioning in these ways: (a) how they engage auditory and visual attention mechanisms; (b) how easily their attention may be disrupted by orienting events; (c) to what degree they are able to spontaneously generate hypotheses about future events based on past experience; and (d) to what degree they are able to attribute different levels of importance to different events. We will assess the possibility that the cognitive difficulties in autism may be different during auditory and visual processing. These possibilities may represent core deficits in autism.

Our research will continue to use a multidisciplinary approach to establish neurophysiological, neuroanatomical, and neurobehavioral markers that differentiate autism from other developmental disorders of communication. (1) Neurophysiological markers will continue to be established by the identification of aberrant sensory and cognitive ERPs in autism and developmental dysphasia. We will determine whether neurophysiological abnormalities in autism occur predominantly in attentional and cognitive, as opposed to sensory, ERPs; whereas in dysphasia, neurophysiological abnormalities occur throughout sensory and cognitive stages of auditory, but not in visual and somatosensory, information processing. (2) Neuroanatomical markers will continue to be established by identifying abnormal neuroanatomical structures using MRI (magnetic resonance imaging) technology. In particular, we will determine whether the distinctive hypoplasia of the cerebellar vermis, which we have found in several non-retarded autistic people, is also present in retarded autistic people, but not in dysphasic and mentally retarded non-autistic people. (3) Neurobehavioral markers will be sought by evaluating the long-term habituation of the acoustic startle response, a potentially distinctive neurobehavioral marker which, heretofore, has not been fully researched in autism. Recent basic research with animals shows that the cerebellar vermis is central to systems which mediate one form of memory -- the long-term habitation of the acoustic startle response. Since our preliminary MRI data has shown that this neuroanatomical structure is abnormal in some autistic people, we will determine whether autistic people have a deficit in the long-term habituation of this response. Neurologic symptoms and signs of cerebellar disorder, such as dysarthria and nystagmus, will be clinically evaluated.

Autism is a disorder of social, intellectual and language functioning. Until recently, few clues to the anatomical basis of autism existed. In 1985, we proposed that a highly probable site of pathology in autism is the neocerebellum. We then tested and confirmed this hypothesis by showing with magnetic resonance (MR) technology that the neocerebellar vermis in autism was statistically significantly reduced in size in 30 adolescents and adults with autism relative to 30 normal controls. We also reported that the cerebellar hemispheres are significantly smaller in autistic subjects. Based on the site and the morphology of the vermian abnormalities, we proposed that these abnormalities are due to early developmental damage that could mark the onset of autism. We now propose to study neuroanatomical development in autism in far greater detail; our findings may have a major impact on the understanding of the etiology, neuroanatomy and neurophysiology of autism. The following issues will be addressed: 1. Are cerebellar abnormalities present at the time of the appearance of the earliest detectable behavioral symptoms of autism (age 2-4 years)? 2. If the cerebellar abnormalities have an early onset, do these abnormalities change with age, or do they remain stable throughout development? 3. If cerebellar abnormalities have a late onset, what is the developmental time-course of these abnormalities? 4. Are there abnormalities of other brain structures present in autism? I so, what are the onset times and developmental time-course of damage within these structures? The structures of greatest interest are: the frontal, temporal, parietal and occipital lobes; the hippocampus; he ventricular system; the basal ganglia; the corpus callosum; the thalamus; and the brainstem. Using MR, we propose to measure the cerebellum and additional CNS structures of greatest interest in groups of retarded and non-retarded autistic children and adolescents of ages 2-4, 6-7, 10-11 and 14-16 years. We will measure the same structures in non-sedated, normal volunteers of comparable age; in-depth comparisons will be performed; longitudinal data will be obtained by re-imaging the three younger groups of autistic abnormal subjects at a later age. Age-related effects will be analyzed.

Autism is a disorder of social, intellectual and language functioning. Until recently, few clues to the anatomical basis of autism existed. In 1985, we proposed that a highly probable site of pathology in autism is the neocerebellum. We then tested and confirmed this hypothesis by showing with magnetic resonance (MR) technology that the neocerebellar vermis in autism was statistically significantly reduced in size in 30 adolescents and adults with autism relative to 30 normal controls. We also reported that the cerebellar hemispheres are significantly smaller in autistic subjects. Based on the site and the morphology of the vermian abnormalities, we proposed that these abnormalities are due to early developmental damage that could mark the onset of autism. We now propose to study neuroanatomical development in autism in far greater detail; our findings may have a major impact on the understanding of the etiology, neuroanatomy and neurophysiology of autism. The following issues will be addressed: 1. Are cerebellar abnormalities present at the time of the appearance of the earliest detectable behavioral symptoms of autism (age 2-4 years)? 2. If the cerebellar abnormalities have an early onset, do these abnormalities change with age, or do they remain stable throughout development? 3. If cerebellar abnormalities have a late onset, what is the developmental time-course of these abnormalities? 4. Are there abnormalities of other brain structures present in autism? I so, what are the onset times and developmental time-course of damage within these structures? The structures of greatest interest are: the frontal, temporal, parietal and occipital lobes; the hippocampus; he ventricular system; the basal ganglia; the corpus callosum; the thalamus; and the brainstem. Using MR, we propose to measure the cerebellum and additional CNS structures of greatest interest in groups of retarded and non-retarded autistic children and adolescents of ages 2-4, 6-7, 10-11 and 14-16 years. We will measure the same structures in non-sedated, normal volunteers of comparable age; in-depth comparisons will be performed; longitudinal data will be obtained by re-imaging the three younger groups of autistic abnormal subjects at a later age. Age-related effects will be analyzed.

DESCRIPTION (Adapted from the applicant's abstract): Infantile autism is a neurobiological disorder in which the development of many higher cognitive, affective, and communicative functions are severely disrupted, resulting in language, social, and integrative deficits. Until recently, the concept that neuroanatomical abnormalities may underlie the neurofunctional deficits in autism has not been systematically investigated. The advent of a powerful, yet non-invasive in vivo imaging method -- magnetic resonance (MR) imaging -- combined with disciplined quantitative measurement algorithms, has made it possible to obtain accurate and meaningful neuroanatomic data from living patients. Comparison of neuroanatomical data obtained in this manner with data from neurofunctional studies in the same patients with autism has yielded important new insights into the disorder. The investigator has disclosed through MR imaging research that specific sites of anatomical abnormalities are present in the parietal lobe and in the cerebellum in diagnostically confirmed autistic patients as young as 5 years of age. Quantitative analysis of MR imaging and neurofunctional data indicate that the size of these specific sites of abnormality is related to the degree of deficit in specific attention operations. For example, the amount of volume loss in superior parietal cortex is highly correlated with the degree of behavioral impairment in detecting stimuli located outside a principal focus of visual attention; such stimuli also elicit abnormally reduced visual neurophysiological responses in autistic patients with the greatest amount of parietal volume loss. Their other studies have found that autistic patients with the most vermian abnormality orient attention more slowly than those who have less vermian abnormality. Parallel studies of patients with autism and patients with acquired focal cerebellar lesions have shown that both patient groups are abnormally slow to shift attention between visual and auditory information, and have abnormally reduced brain responses to cues signalling attention shifts. These findings show great promise in elucidating the relationship between brain site and function in autism and in the normal brain, but require confirmation in the carefully designed brain-behavior studies outlined in this proposal. To explore the relationship between sites of anatomical abnormality and deficits in specific attention operations in autism, the investigator proposes to acquire in autistic and normal subjects behavioral and neurophysiological measures of three specific operations -- orienting, shifting, and distributing attention -- a statistically correlate these measures with the size of various cerebral, cerebellar, and subcortical structures. They also propose to acquire functional MR imaging measures in order to more directly identify anatomical structures whose deficits underlie impairment in shifting attention in autism. The completion of this study will further their long-term objective of elucidating the anatomical substrate of neurofunctional deficits in autism.

Autism is a neurologic disorder of unknown cause that severely disrupts social, cognitive, and language development. While we and other groups have made progress in identifying anatomical abnormalities in the mature autistic brain, there is little direct knowledge of the sites and types of abnormality characteristic of the autistic infant, and no knowledge of subsequent growth changes. Overall goals of our MRI research are to (1) identify anatomical defects in autistic infants and toddlers; (2) determine abnormal patterns of growth from infancy to early childhood; (3) replicate newly discovered anatomical abnormalities in 2.5 to 5 year old autistic patients; and (4) determine abnormal patterns of growth from middle childhood through adulthood by completing analyses of already collected longitudinal MRI data on autistic and normal control subjects. In our funded MRI research, we have identified specific sites and types of structural and growth abnormality in autistic patients ages 29 months through 42 years. Cerebellar vermis and dentate gyrus were both hypoplastic at the earliest ages examined, but only the dentate showed subsequent age-related increase in size. Striking overgrowth of cerebrum, especially its frontal and temporoparietal regions, was seen in the youngest patients, but subsequent growth was negligible. We hypothesize that a surprising and complex pattern of abnormal regional growth emerges very early in autistic development and an best be captured in studies of autistic infants and toddlers, ages not previously studied by us and only examined in one MRI study in the literature. In our proposed research we will use MRI technologies to identify patterns of pathological growth changes in autism from late infancy (18- 30 months) through early childhood. Subject groups will be autistic, normally and mentally retarded non-autistic. We will also obtain similar neuroanatomical information about infants with PDD-NOS, and thereby gain insight into anatomical abnormalities within the wider autism spectrum. To achieve these goals, we will use a prospective diagnosis and longitudinal MRI procedure. Lastly, we will continue the quantitative measurement of our present sample of 220 subjects (children and adults with autism, and normal controls) acquired as part of our current 5 year longitudinal MRI study. Results from the proposed research will provide knowledge of the developmental anatomic phenotype in autism.

[unreadable] DESCRIPTION (provided by applicant): Autism is a developmental disorder, but the least is known about what is most important: Development. What are the early brain abnormalities? What neural functions do they disrupt? What the first behavioral indicators of risk for autism? What is the prognosis for the toddler or child at first diagnosis? Which are likely to respond to known effective treatment and which not? Are their brain or other biological markers that could predict non-responders so that treatment research could be targeted towards discovery of treatments that could help them? What genes and gene pathways are responsible for early brain defects? The answer to each question comes to the same point: Early identification methods. These sorts of crucial questions cannot be addressed unless there is a way to identify infants at risk for autism. The most popular method is the infant sibling method. Now many groups are trying this method. The first two laboratories to use this method began their research five and seven years ago, and have published two original papers, one on 7 autism spectrum (ASD) infants and one on 27 ASD infants. They found no differences from typical development at 6 months, but did by 12 months. They provided no brain, neurofunctional, genetic or other biological data on the ASD infants. The infant sibling method has major cost, practicality and methodological limitations, which are detailed in our grant. Although popular and in progress for a long time, to date, studies using this method have provided no answer any of the major questions posed above. A simpler, quicker, more flexible, cost-effective and more clinically relevant and practical method is to study individuals referred by physicians because they display behavioral symptoms indicating risk for an ASD. In the 1990s, this method resulted in identification of mostly at-risk 3 year olds and up. By the early 2000s, the at-risk age for referral was age 2 years because of heightened awareness by physicians and new diagnostic tools. In each "era", others and we were able to vigorously investigate brain and behavior abnormalities and new treatment approaches at young ages in ASD. It was via this simple referral method that major discoveries about early brain overgrowth in ASD occurred in our laboratory. It was via this method that we have been able to perform the first fMRI activation studies on ASD at age 2-years. Now, via a novel variant of this proven effective prospective method (see Core B), in our ACE Center we will study 12-month old infants at-risk for ASD, infants at-risk for developmental delay and typical infants using advanced biological and behavioral methods. Each infant will be studied at intervals longitudinally and a final best estimate diagnosis made at 36 months providing a final step for group assignment for statistical [unreadable] [unreadable] [unreadable]

In autism, early-age biomarkers are scarce. Research is urgently needed to identify markers that precede symptom onset, convey prognostic information, or indicate disorder subtypes. Our proposed functional genomics study of early development in ASD addresses many of these biomarker goals and is an essential early step in this discovery process. Robust biomarkers have been elusive presumably since ASD is a heterogeneous developmental disorder with thousands of speculated risk genes and potential non-genetic immune factors. We hypothesize that pathway-based transcriptomic biomarkers may be informative, as shown by our recent proof- of-concept study in which leukocyte-based gene expression provided an early diagnostic ASD classifier. Our findings are reasonable since many high confidence ASD genes (e.g., transcription factors, signaling genes, etc.) and networks are as strongly expressed in leukocytes as in brain. Furthermore, hypothesized immune disruptions in ASD should also be reflected in leukocytes, especially since microglia are a type of leukocyte that are established as a brain molecular and cellular pathology in ASD. In our proposed study, we will use 1,500 RNA-Seq datasets from 1,000 ASD and typically and atypically developing toddlers to identify biomolecular pathway biomarkers for early detection, prognosis, clinical progression and clinical subtyping. We will further study biomarker relationships to ASD gene defects and expression patterns in early neural development. Aim 1 will analyze RNA-Seq data from 1,000 1-2 year olds using data-driven and knowledge-based network approaches to identify early ASD diagnostic biomarkers that distinguish ASD (n=390) at ages 1-2 years from non-ASD (n=610) groups. Diagnostic biomarkers will include pathways and co-expression networks to address the heterogeneity across ASD subjects. Aim 2 will identify prognostic RNA-Seq expression patterns in the 390 ASD 1-2 year olds by analyzing gene expression levels to reveal pathways that predict good/poor social and language outcome at ages 3-4 years. Aim 2 will also look longitudinally at ASD (n=300) and typically developing (n=200) expression data to identify transcriptomic trajectories that underlie clinical progression from 1-2 years to 3-4 years in these different clinical outcome subgroups. Aim 3 will examine how variation in developmental functional genomic patterns relates to variation in social and language abilities across diagnostic categories (n=1,000) and within ASD (n=390) using dimensionality reduction and feature selecting regression. Multicollinear regressions will be used to combine multivariate trend observations of dimensionality reduction with the predictive power of regressions. Aim 4 will link key transcriptomic effects in Aims 1 to 3 to genetic variants in high-confidence and probable ASD genes that are linked to disrupted cellular pathways in our ASD subjects. Deleterious variants in those genes will be tested in hematopoietic and neural stem cells using CRISPR-Cas9 to introduce loss-of-function mutations in these genes. RNA-Seq will be used to assay the impact on ASD-relevant cellular pathways.