06-23-2005, 09:15 PM
There are some studies being done using PET scans. Not much information yet. Interesting what the article says about facial recognition.
http://www.emedicine.com/neuro/topic440.htm
"Autistic disorder is a class of pervasive developmental disorders that present in early childhood and are characterized by marked abnormalities in language, communication, and social interactions and by a restricted and peculiar range of interests and activities. The male-to-female ratio of patients with autistic disorder is approximately 3-4:1. Most people with autistic disorder also exhibit mental retardation and approximately one third of people have seizure disorders.
Exposure to toxins, poisons, residues, and other contaminants is one of the mechanisms hypothesized to cause autism and related conditions. While evidence exists that toxic exposure may play a role in isolated cases of autism, no convincing evidence that toxic exposure is instrumental in the causation of autism in the population in general has been reported. In particular, anecdotal reports that autism developed in children who received immunization to measles, mumps, and rubella have not been confirmed in the general population. Thus, immunization is not associated with the development of autism in general. For this reason, routine immunizations, including immunization for measles, mumps, and rubella, are recommended for the general population.
Autism spectrum disorders include autistic disorder, Asperger disorder, Rett disorder, childhood disintegrative disorder, and other pervasive developmental disorders. For additional information about autistic disorder, please refer to the article Pervasive Developmental Disorder: Autism in the Pediatrics journal. For additional information about Asperger syndrome, please refer to the article Pervasive Developmental Disorder: Asperger Syndrome in the Pediatrics journal.
Autism spectrum disorders include pervasive developmental disorders not otherwise specified. Thus, autism spectrum disorders include autistic disorder as well as conditions with some features of autistic disorder and without all criteria required for autistic disorder. Autistic disorder is probably a heterogeneous condition with multiple causes, some of which are unknown.
A major concern in the interpretation of reports about positron emission tomography (PET) scans in autism spectrum disorders is the accuracy and the precision of the diagnoses. The widely used systems of nomenclature, including the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) (American Psychiatric Association, 2000) and the International Classification of Diseases, Ninth Revision, Clinical Modification, Fourth Edition (ICD-9-CM) (NCHS, 1993) list criteria for several autism spectrum disorders.
While both DSM-IV-TR and ICD-9-CM contain criteria for various autism spectrum disorders, those criteria are listed in an outline fashion that challenges inexperienced readers. Those who are expert in autism spectrum disorders know what the terms of DSM-IV-TR and ICD-9-CM mean. On the other hand, the sketchy descriptions of both DSM-IV-TR and ICD-9-CM are prone to misinterpretation by inexperienced readers. Therefore, attempts by inexperienced individuals to diagnose autism spectrum disorders by the application of criteria from DSM-IV-TR and ICD-9-CM are fraught with error.
Specialized diagnostic procedures have been developed for autistic disorder and other autism spectrum disorders. The diagnostic tools for autism spectrum disorders require training in order to attain a reliable administration. The detailed description of the procedures to diagnosis autistic disorder and other autism spectrum disorders is beyond the scope of this article. Please refer to the articles Pervasive Developmental Disorder: Autism and Pervasive Developmental Disorder: Asperger Syndrome in the Pediatrics journal for suggestions about screening for these conditions in clinical and research settings. When in doubt about the possible presence of autism spectrum disorders, please refer the individual to a clinician experienced in the diagnosis of autism spectrum disorders for a definitive evaluation.
Clinical symptoms of autism spectrum disorders include problems with social interaction, problems in making friends, and limited nonverbal communication. Since social deficits are a hallmark of autism spectrum disorders, researchers are investigating the nature of nonverbal communications, including facial recognition and interpretation of affect exhibited by facial expressions. The understanding of hand gestures and eye gaze provides crucial clues about the feelings and intentions of others. Persons with autism spectrum disorders exhibit deficits in facial perception. Instead of identifying people on the basis of overall facial configuration, persons with autism spectrum disorders use the lower face, the mouth, and other specific portions of the face to identify others. Thus, people with autism spectrum disorders actually may identify the faces of people by focusing on the objects that form the face rather than the whole person.
Megalencephaly has been reported in a few cases of autistic disorder. Thus, a subset of individuals with autistic disorder may be characterized by this finding.
The cerebella of some individuals with autistic disorder demonstrate hypoplasia while others demonstrate hyperplasia. Additionally, oculomotor studies have provided evidence of neocortical dysfunction of the prefrontal cortex and connections to the parietal lobe. Separate subgroups with neocortical dysfunction and others with cerebellar dysfunction may exist.
Perception is accomplished in the brain by means of a parietal pathway for spatial and motor function and a temporal pathway for identification of objects, faces, and gestures. Anomalies in the amygdala and other structures of the medial temporal lobe have been demonstrated repeatedly in autism spectrum disorders, suggesting involvement of the temporal pathway for visuoperceptual processing. Functional magnetic resonance imaging (fMRI) of people with autism spectrum disorders demonstrates reduced activation in the fusiform gyrus, the portion of the brain associated with facial recognition, and increased activation of adjacent portions of the brain associated with recognition of objects. fMRI also suggests that, in some individuals with Asperger syndrome and high-functioning autism, dysfunctional connections among limbic and paralimbic regions, the cerebellum, and the extrastriate visual cortices occur during the process of identification of the emotion expressed by faces and the gender of the face.
Rett disorder is a condition presenting in childhood in girls only. This disorder is characterized by progressive loss of skills and relentless deterioration of neurologic functioning.
A variety of personal and clinical data is relevant to the analysis of studies of individuals with autism spectrum disorders. Specifically the presence of claustrophobia or scoliosis may interfere with the ability to hold still for scans. Additionally the use of nicotine, caffeine, alcohol, and drugs may have short-term and long-term effects on the brain so current and past use of substances is relevant. The presence of other medical, neurological, psychiatric, and psychological conditions may affect the scans of the individual. Therefore, knowledge of all current and prior physical and emotional disorders is crucial.
The history of a suicide attempt is important because subjects experience both physical and psychological stress before, during, and after scans. Individuals who are acutely suicidal merit inpatient psychiatric hospitalization. Generally, subjects who are suicidal are not appropriate for scans for research purposes. (The special needs of research on suicide are beyond the scope of this article.)
In order to obtain relevant screening information on all potential research subjects, we have prepared a Questionnaire for Subjects (see Picture 9 for a printable version). The Questionnaire for Subjects can be sent to individuals as part of the screening process.
Potential subjects for research studies can be excluded from further participation if the presence of exclusionary criteria is identified on review of the Questionnaire for Subjects. For clinical studies, the presence of positive findings on the Questionnaire for Subjects indicates the need for tailoring the future studies to the needs and limitations of the individual.
After review of the Questionnaire for Subjects confirms that the person is suitable for further evaluation, then a medical history and physical examination must be accomplished before nuclear studies are performed. Structured interviews, using a Nuclear Medical History Recording Form (see Picture 10 for a printable version) and examinations, using the Nuclear Medical Physical Examination Recording Form (see Picture 11 for a printable version) are helpful to verify that an adequate assessment has been obtained for nuclear medical procedures.
Typically, research subjects have few findings on medical history and physical examination. The presence of positive findings on medical history and physical examination indicates the need to verify the absence of exclusionary criteria for research studies. Also, the presence of positive findings on medical history and physical examination indicates the need for consideration of possible contraindications for clinical studies. The needs and limitations of each individual must be considered before proceeding with nuclear studies.
Because the findings in the brains of people with autism and related conditions may be lateralized, identification of the lateral preferences of the subject is a crucial component of the examination of each subject. Denckla (1985) developed a quick procedure, suitable for clinical settings, that is used to identify the lateral preferences for the use of the eye, the hand, and the foot in children, adolescents, and adults. Before scans of the brain are performed, the Lateral Preferences Examination Form (see Picture 12 for a printable version) is completed for all subjects to identify the preferred side for the eye, the foot, and the hand.
The examiner scores the Lateral Preferences Examination in vivo. In addition to the live rating by the examiner, the Lateral Preferences Examination is videotaped for later blind rating by experts unfamiliar with the status of the subject. The blind videotape rating of the Lateral Preferences Examination is useful to determine reliability of the live ratings of the exam.
Additionally, blind rating of the videotape of the Lateral Preferences Examination is useful to protect against any left-right dissociation in the examiner. Examiners may experience confusion themselves in determining the side used by the subjects for each task. Therefore, rating of videotaped assessments is a crucial component of research studies of scans of the brain.
For excellent patient education resources, visit eMedicine's Brain and Nervous System Center. Also, see eMedicine's patient education article Autism."
http://www.emedicine.com/neuro/topic440.htm
"Autistic disorder is a class of pervasive developmental disorders that present in early childhood and are characterized by marked abnormalities in language, communication, and social interactions and by a restricted and peculiar range of interests and activities. The male-to-female ratio of patients with autistic disorder is approximately 3-4:1. Most people with autistic disorder also exhibit mental retardation and approximately one third of people have seizure disorders.
Exposure to toxins, poisons, residues, and other contaminants is one of the mechanisms hypothesized to cause autism and related conditions. While evidence exists that toxic exposure may play a role in isolated cases of autism, no convincing evidence that toxic exposure is instrumental in the causation of autism in the population in general has been reported. In particular, anecdotal reports that autism developed in children who received immunization to measles, mumps, and rubella have not been confirmed in the general population. Thus, immunization is not associated with the development of autism in general. For this reason, routine immunizations, including immunization for measles, mumps, and rubella, are recommended for the general population.
Autism spectrum disorders include autistic disorder, Asperger disorder, Rett disorder, childhood disintegrative disorder, and other pervasive developmental disorders. For additional information about autistic disorder, please refer to the article Pervasive Developmental Disorder: Autism in the Pediatrics journal. For additional information about Asperger syndrome, please refer to the article Pervasive Developmental Disorder: Asperger Syndrome in the Pediatrics journal.
Autism spectrum disorders include pervasive developmental disorders not otherwise specified. Thus, autism spectrum disorders include autistic disorder as well as conditions with some features of autistic disorder and without all criteria required for autistic disorder. Autistic disorder is probably a heterogeneous condition with multiple causes, some of which are unknown.
A major concern in the interpretation of reports about positron emission tomography (PET) scans in autism spectrum disorders is the accuracy and the precision of the diagnoses. The widely used systems of nomenclature, including the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) (American Psychiatric Association, 2000) and the International Classification of Diseases, Ninth Revision, Clinical Modification, Fourth Edition (ICD-9-CM) (NCHS, 1993) list criteria for several autism spectrum disorders.
While both DSM-IV-TR and ICD-9-CM contain criteria for various autism spectrum disorders, those criteria are listed in an outline fashion that challenges inexperienced readers. Those who are expert in autism spectrum disorders know what the terms of DSM-IV-TR and ICD-9-CM mean. On the other hand, the sketchy descriptions of both DSM-IV-TR and ICD-9-CM are prone to misinterpretation by inexperienced readers. Therefore, attempts by inexperienced individuals to diagnose autism spectrum disorders by the application of criteria from DSM-IV-TR and ICD-9-CM are fraught with error.
Specialized diagnostic procedures have been developed for autistic disorder and other autism spectrum disorders. The diagnostic tools for autism spectrum disorders require training in order to attain a reliable administration. The detailed description of the procedures to diagnosis autistic disorder and other autism spectrum disorders is beyond the scope of this article. Please refer to the articles Pervasive Developmental Disorder: Autism and Pervasive Developmental Disorder: Asperger Syndrome in the Pediatrics journal for suggestions about screening for these conditions in clinical and research settings. When in doubt about the possible presence of autism spectrum disorders, please refer the individual to a clinician experienced in the diagnosis of autism spectrum disorders for a definitive evaluation.
Clinical symptoms of autism spectrum disorders include problems with social interaction, problems in making friends, and limited nonverbal communication. Since social deficits are a hallmark of autism spectrum disorders, researchers are investigating the nature of nonverbal communications, including facial recognition and interpretation of affect exhibited by facial expressions. The understanding of hand gestures and eye gaze provides crucial clues about the feelings and intentions of others. Persons with autism spectrum disorders exhibit deficits in facial perception. Instead of identifying people on the basis of overall facial configuration, persons with autism spectrum disorders use the lower face, the mouth, and other specific portions of the face to identify others. Thus, people with autism spectrum disorders actually may identify the faces of people by focusing on the objects that form the face rather than the whole person.
Megalencephaly has been reported in a few cases of autistic disorder. Thus, a subset of individuals with autistic disorder may be characterized by this finding.
The cerebella of some individuals with autistic disorder demonstrate hypoplasia while others demonstrate hyperplasia. Additionally, oculomotor studies have provided evidence of neocortical dysfunction of the prefrontal cortex and connections to the parietal lobe. Separate subgroups with neocortical dysfunction and others with cerebellar dysfunction may exist.
Perception is accomplished in the brain by means of a parietal pathway for spatial and motor function and a temporal pathway for identification of objects, faces, and gestures. Anomalies in the amygdala and other structures of the medial temporal lobe have been demonstrated repeatedly in autism spectrum disorders, suggesting involvement of the temporal pathway for visuoperceptual processing. Functional magnetic resonance imaging (fMRI) of people with autism spectrum disorders demonstrates reduced activation in the fusiform gyrus, the portion of the brain associated with facial recognition, and increased activation of adjacent portions of the brain associated with recognition of objects. fMRI also suggests that, in some individuals with Asperger syndrome and high-functioning autism, dysfunctional connections among limbic and paralimbic regions, the cerebellum, and the extrastriate visual cortices occur during the process of identification of the emotion expressed by faces and the gender of the face.
Rett disorder is a condition presenting in childhood in girls only. This disorder is characterized by progressive loss of skills and relentless deterioration of neurologic functioning.
A variety of personal and clinical data is relevant to the analysis of studies of individuals with autism spectrum disorders. Specifically the presence of claustrophobia or scoliosis may interfere with the ability to hold still for scans. Additionally the use of nicotine, caffeine, alcohol, and drugs may have short-term and long-term effects on the brain so current and past use of substances is relevant. The presence of other medical, neurological, psychiatric, and psychological conditions may affect the scans of the individual. Therefore, knowledge of all current and prior physical and emotional disorders is crucial.
The history of a suicide attempt is important because subjects experience both physical and psychological stress before, during, and after scans. Individuals who are acutely suicidal merit inpatient psychiatric hospitalization. Generally, subjects who are suicidal are not appropriate for scans for research purposes. (The special needs of research on suicide are beyond the scope of this article.)
In order to obtain relevant screening information on all potential research subjects, we have prepared a Questionnaire for Subjects (see Picture 9 for a printable version). The Questionnaire for Subjects can be sent to individuals as part of the screening process.
Potential subjects for research studies can be excluded from further participation if the presence of exclusionary criteria is identified on review of the Questionnaire for Subjects. For clinical studies, the presence of positive findings on the Questionnaire for Subjects indicates the need for tailoring the future studies to the needs and limitations of the individual.
After review of the Questionnaire for Subjects confirms that the person is suitable for further evaluation, then a medical history and physical examination must be accomplished before nuclear studies are performed. Structured interviews, using a Nuclear Medical History Recording Form (see Picture 10 for a printable version) and examinations, using the Nuclear Medical Physical Examination Recording Form (see Picture 11 for a printable version) are helpful to verify that an adequate assessment has been obtained for nuclear medical procedures.
Typically, research subjects have few findings on medical history and physical examination. The presence of positive findings on medical history and physical examination indicates the need to verify the absence of exclusionary criteria for research studies. Also, the presence of positive findings on medical history and physical examination indicates the need for consideration of possible contraindications for clinical studies. The needs and limitations of each individual must be considered before proceeding with nuclear studies.
Because the findings in the brains of people with autism and related conditions may be lateralized, identification of the lateral preferences of the subject is a crucial component of the examination of each subject. Denckla (1985) developed a quick procedure, suitable for clinical settings, that is used to identify the lateral preferences for the use of the eye, the hand, and the foot in children, adolescents, and adults. Before scans of the brain are performed, the Lateral Preferences Examination Form (see Picture 12 for a printable version) is completed for all subjects to identify the preferred side for the eye, the foot, and the hand.
The examiner scores the Lateral Preferences Examination in vivo. In addition to the live rating by the examiner, the Lateral Preferences Examination is videotaped for later blind rating by experts unfamiliar with the status of the subject. The blind videotape rating of the Lateral Preferences Examination is useful to determine reliability of the live ratings of the exam.
Additionally, blind rating of the videotape of the Lateral Preferences Examination is useful to protect against any left-right dissociation in the examiner. Examiners may experience confusion themselves in determining the side used by the subjects for each task. Therefore, rating of videotaped assessments is a crucial component of research studies of scans of the brain.
For excellent patient education resources, visit eMedicine's Brain and Nervous System Center. Also, see eMedicine's patient education article Autism."