Childhood psychosis and computed tomographic brain scan findings

Left hemisphere & cerebellar damage in Asperger's syndrome

A case of Asperger's syndrome is presented with evidence of left hemisphere and cerebellar abnormalities.

Normal rates of neuroradiological findings in children with high functioning autism

Magnetic resonance imaging (MRI) has been used to analyze highly specific volumetric and morphological features of the brains of individuals with autism spectrum disorder (ASD). To date, there are few comprehensive studies examining the prevalence of neuroradiologic findings seen on routine MRI scans in children with ASD. This study examined the prevalence of neuroradiologic findings in children with high functioning ASD, and compared these rates to those in children with Attention-Deficit/Hyperactivity Disorder (ADHD) and children who are typically developing (TD). Results showed that approximately 90% of children had normal MRI scans. There was no significant effect of diagnosis on the total number of neuroradiological findings or the number of specific brain findings. Implications and future research directions are discussed.

A systems neuroscience approach to autism: biological, cognitive, and clinical perspectives

Autism is a behaviorally defined disorder characterized by a broad constellation of symptoms. Numerous studies directed to the biological substrate demonstrate clear effects of neurodevelopmental differences that will likely point to the etiology, course, and long-term outcomes of the disorder. Consistently replicated research on the neural underpinnings of autism is reviewed. In general, results suggest several main conclusions: First, autism is a heterogeneous disorder and is likely to have multiple possible etiologies; second, structural brain studies have indicated a variety of diffuse anatomical differences, reflective of an early developmental change in the growth or pruning of neural tissue, rather than localized lesions; similarly, neurochemical studies suggest early, neuromodulatory discrepancies rather than gross or localized abnormalities; and finally, there are a number of limitations on studies of brain activity that to date preclude definitive answers to questions of how the brain functions differently in autism. The large number of active research programs investigating the cognitive neuroscience of autism spectrum disorders, in combination with the exciting development of new methodologies and tools in this area, indicates the drama and excitement of work in this area.

Neuroimaging in autism

BACKGROUND

Childhood autism is a developmental disorder with distinctive clinical features and characteristic cognitive deficits. Neuroimaging techniques have been extensively used in the study of autism and related disorders.

METHOD

Recent important literature reported on structural and functional neuroimaging in autism was reviewed and discussed in the context of other neurobiological research findings.

RESULTS

Various abnormalities of brain structure and function have been proposed, but no focal defect has been reliably demonstrated. Important findings, so far, include increased brain volume, structural abnormality in frontal lobe and corpus callosum in a proportion of autistic individuals. Functional neuroimaging findings emphasised the imbalance in inter-regional and inter-hemispheric brain metabolism and blood flow as well as abnormality in the anterior cingulate gyrus.

CONCLUSION

The research to date has been hindered by methodological difficulties. However, hypothesis-driven research, particularly involving activation studies and neurotransmitter/neuroreceptor activities, using functional neuroimaging will be very useful in unravelling the enigma associated with this intriguing and distressing condition.

Genetics of autism: overview and new directions

Genetic epidemiology is the study of inherited factors involved in the etiology of a disease or disorder and uses the methods of both medical genetics and clinical epidemiology. In general, genetic epidemiology tries to answer the following four questions: Is the disorder inherited; What phenotype is inherited; How is it inherited or what is the mode of transmission; and What is the nature of the genetic mutation, if any, that gives rise to the disorder? The hope is that by identifying the gene or genes involved in pathophysiology, a much better understanding of the steps from gene product to phenotype will be possible, leading to improvements in diagnosis, an opportunity for thoughtful family planning, and perhaps, most important, to the development of treatments based on an understanding of the biochemistry of the disorder. We review the current knowledge of the genetic epidemiology of autism and the other pervasive developmental disorders (PDDs) and highlight promising new directions. There seems to be widespread agreement that the PDDs are caused, at least in part, by genetic factors. There is also some agreement on the phenotypic boundaries associated with these same genetic factors. However, many points of uncertainty remain, and several methodologic issues need to be resolved before further progress in mapping susceptibility genes is possible. We do not specifically review molecular studies, medical conditions associated with autism, or the broader autism phenotype, as these topics are covered in other papers in this special issue.

Neuropathological study of a case of autistic syndrome with severe mental retardation

Infantile autism is a syndrome of unknown aetiology and unknown neuro-anatomic substrate. The authors report a histological study of the brain of a well-documented 16-year-old female with autistic syndrome and severe mental retardation, using direct microscopic examination of the whole brain. The major findings are low brain weight, a thin corpus callosum and ventricular dilatation. No abnormalities were found in the hippocampus or cerebellum. Excessive axonal elimination during brain development is hypothesized. The relations of hypothetical developmental events with the clinical features of autistic syndrome are discussed.

Autism: towards an integration of clinical, genetic, neuropsychological, and neurobiological perspectives

Autism constitutes one of the best validated child psychiatric disorders. Empirical research has succeeded in delineating the key clinical phenomena, in demonstrating strong genetic influences on the underlying liability, and in identifying basic cognitive deficits. A range of neurobiological abnormalities has also been found, although the replicability of specific findings has not been high. An understanding of the causal processes leading to autism, and accounting for the marked variability in its manifestations, requires an integration across these different levels of enquiry. Although this is not yet possible, a partial integration provides a useful strategy for identifying key research questions, the limitations of existing hypotheses, and future research directions that are likely to prove fruitful. The research findings for each research level are critically reviewed in order to consider how to move towards an integration across levels.

Brainstem involvement in high functioning autistic children

To determine involvements of the brainstem and/or cerebellum in autism, we compared midsagittal magnetic resonance images of the brains of high functioning autistic children with those of normal controls. We found that the midbrain and medulla oblongata were significantly smaller in these autistic children than in the control children. The pons area did not differ between the two groups, nor was there any difference in the cerebellar vermis area. The ratio of the brain stem and cerebellum to the posterior fossa area did not differ significantly between the high functioning autistic and the control children. A positive correlation between age and area of the cerebellar vermis was observed in autistic children but not in control children. Thus, it was suggested that significant anatomical changes in the midbrain and medulla oblongata existed in the autistic children and that growth of the cerebellar vermis in autistic children was different from normal children.

SPECT (Single Photon Emission Computed Tomography) in 31 children and adolescents with autism and autistic-like conditions

SPECT with Tc-99m-HM-PAO was used in examining 31 patients with autism and autistic-like conditions. Sixteen of these had autistic disorder/autistic-like conditions with associated epilepsy. The autistic disorder group without epilepsy was relatively high functioning. All 31 patients showed reduction of regional cerebral blood flow in the temporal lobes. There was no clear difference between the groups with and without epilepsy, suggesting that seizure disorder per se could not account for the findings.

The neurobiology and genetics of infantile autism

Autism is a syndrome with multiple etiologies, as is made clear both by the evidence of neurobiological research and by the catalog of disorders that present with autistic behaviors. What remains unclear are the specific neuropathological mechanisms that produce autistic behaviors; for example, is there a common neuroanatomic pathology for all cases of autism, or can autistic behaviors emerge from different pathological sequences within the brain? Although it is premature to generalize, neuropathological studies appear to have identified common abnormalities in the cerebellum and limbic system of at least five autistic subjects. These subjects, with variable levels of mental retardation, demonstrated marked Purkinje cell loss in the cerebellar hemispheres, together with retained fetal neuronal circuitry in cerebellar nuclei and increased neuronal packing in specific regions of the limbic system, amygdala, and hippocampus. The architecture of the cerebral cortex was not affected. Although our knowledge of brain functioning is incomplete, alterations of the kind noted in the cerebellum and limbic system could reasonably produce autistic behaviors. For more detail, readers are directed to a review of cerebellar contributions to higher functions by Schmahmann (1991). Neuroimaging studies allow less resolution of brain structure than do neuroanatomic studies, and the reported findings from neuroimaging are somewhat contradictory. However, a number of investigators have reported structural abnormalities in ventricle size and cerebral hemispheric asymmetry using CT. MRI, which offers greater resolution, has uncovered some consistent findings, along with a variety of nonspecific abnormalities. Common abnormalities include reduced volume of cerebellar hemispheres and vermal lobules--findings not inconsistent with the above-mentioned neuropathological defects. It is also interesting to note that individuals with fragile X syndrome have similar cerebellar findings. PET and NMR studies of autism are at a preliminary stage, but these methodologies allow insight into the functioning of the brain, rather than simply brain anatomy. Recent PET studies indicating decreased association between paired regions of the brains of autistic subjects are of interest, particularly if they can be confirmed and refined by additional studies. Neurophysiological studies also offer insight into brain function, but are subject to numerous methodological criticisms. Nevertheless, recent reports of diminished P300 waves and absent NC components in autistic subjects seem to indicate fundamental defects in attention and secondary processing, which could help explain the self-stimulatory behaviors often seen in autism. The disturbances in brain development associated with autism can be produced in a number of ways, and at different times during development of the nervous system.(ABSTRACT TRUNCATED AT 400 WORDS)

Magnetic resonance imaging of the brain structures in the posterior fossa in retarded autistic children

Midsagittal magnetic resonance images of the brains of retarded autistic children were compared to those of non-autistic mental retardation patients and controls. We found that the whole brain stem and particularly two of its components (the midbrain and medulla oblongata) were significantly smaller in retarded autistic children and mental retardation cases than in control children. The pons area was significantly smaller in mental retardation cases as compared to control children but did not differ between autistic and control children. Moreover, there was no difference in the brain stem between retarded autistic children and mental retardation cases. We also noted no difference in the cerebellar vermis area among retarded autistic children, mental retardation cases and control children. The ratio of the midbrain to posterior fossa area was significantly smaller only in autistic patients. Although the significance of these results is unknown, further examination of autistic children with a normal IQ is necessary.

Reduced brainstem size in children with autism

Recently, structural brain abnormalities as well as functional abnormalities of the brainstem have been reported in autistic children. The authors undertook an analytic study of the brainstem in autistic children by means of magnetic resonance imaging (MRI). The MRI scans of 29 autistic children were compared with 15 control MRI scans. The autistic children were divided into two groups according to DQ (IQ) level: the DQ (IQ) greater than or equal to 80 group and the DQ (IQ) less than 80 group. The midbrain and pons were measured, and the ratio of the midbrain and pons sizes versus the cranium size were calculated. The brainstem size was found to be significantly smaller in the autistic group. In particular, the reduction in brainstem size tended to be greater in the low DQ (IQ) group when compared with the high DQ (IQ) one, though there was no significant difference (p less than 0.1). This suggests that the brainstem is anatomically altered in autistic children.

IQ and the genetics of autism

While there seems to be general agreement that genetic factors play some role in the etiology of autism, many important questions remain unresolved. The purpose of this paper is to review five issues with respect to the association between low IQ and autism from a familial-genetic viewpoint: (1) does IQ estimate the severity of the autistic genotype?; (2) what is the relationship between probands' and sibs' IQs?; (3) what is the relationship between parents' and probands' IQs?; (4) why do females with autism have lower IQs than males with the disorder?; and (5) does IQ vary with the cause of autism? With respect to each issue, possible resolutions are outlined, as are the implications for understanding the genetic mode of transmission. The review concludes with a possible model for the genetic etiology of autism.

Neuropsychiatric assessment of children with autism: a population-based study

Thirty-five children with autistic disorder and 17 with autistic-like conditions underwent an exhaustive neurobiological evaluation, and the findings were contrasted with those obtained from various comparison groups. Almost 90 per cent of the children with autistic disorder and autistic-like conditions had major indications of brain damage or dysfunction. Some of those who did not show such abnormalities had a first-degree relative with Asperger syndrome. The rate of abnormality was similar to that of severely mentally retarded children, but in excess of that of normal children. Within the autism group, abnormality rate did not correlate with degree of mental retardation. It is concluded that autism has multiple biological aetiologies and that autistic symptoms in a child should always prompt a thorough medical/neurobiological evaluation.

Low field magnetic resonance imaging of the central nervous system in 15 children with autistic disorder

Fifteen children, 10 boys and 5 girls, with autistic disorder, were studied with low field magnetic resonance imaging (MRI). The age ranged from 2.7-13.1 years, with a mean of 8.3 years. All patients but one (who refused) had a normal CT scan of the C.N.S. The MRI investigation was performed during anaesthesia with a low field magnetic resonance imager. The cerebrum, cerebellum, and brain stem were examined. No pathological changes were found in any of the patients studied.

Neuroimaging in child and adolescent psychiatry

Although less well studied in child and adolescent psychiatry than in adult psychiatry, brain imaging has significantly altered psychiatric research and practice. This review focuses on the modalities that are used to image the brain. These include structural imaging techniques of computer tomography (CT) and magnetic resonance imaging (MRI), as well as functional imaging techniques of computed electroencephalography (CEEG), positron emission tomography (PET), and single photon emission computed tomography (SPECT). The technologies are reviewed, strengths and weaknesses of modalities discussed, and research progress reported.

Forebrain structure in infantile autism

Researchers implicate central nervous system dysfunction in infantile autism, but postmortem examinations and in vivo brain imaging studies have produced conflicting results concerning the neuronal systems involved. Magnetic resonance imaging--a new modality of in vivo brain imaging--was used to investigate the cerebral and thalamic structure of 105 autistic patients. Compared with the control group, there was an overall difference in the forebrain morphology of the autistic subjects due to subtle but statistically significant differences in the anterior ventricular horns, lateral ventricles, and the right lenticular nucleus. These results, when considered with previous studies of cerebral structure, suggest that there are subtle alterations in the forebrain of autistic patients.

Infantile autism and computerized tomography brain-scan findings: specific versus nonspecific abnormalities

The hypothesis that specific computerized tomography brain-scan findings are associated with infantile autism was tested in 45 cases and 19 controls. The autistic group was subdivided into serious and less-serious language-impaired subgroups. The analysis of Euclidean Distances, a type of cluster analysis, showed that neuroradiological parameters of cases and controls, including ventricular sizes, were on the whole significantly different, but no statistically significant difference appeared between the two autistic subgroups. But the analysis of variance of each neuroradiological parameter did not show any significant difference between autistics and controls. It was concluded that autism is nonspecifically associated with brain-scan abnormalities, and that other nonorganic, as well as organic, factors should be taken into account.

Cerebral blood flow and metabolism of oxygen and glucose in young autistic adults

Regional cerebral blood flow, oxygen consumption and glucose consumption were measured by positron emission tomography in six young autistic men. No significant differences were found between patients and normal controls for any of the physiological variables. The results do not substantiate the previous finding of glucose hypermetabolism in autism; the likely reasons for the variance in findings are discussed.

New perspectives in autism, Part II: The differential diagnosis and neurobiology of autism

The clinical spectrum of autism spans a broad range of functions, but the core symptoms remain the same regardless of the intelligence of the child: the autistic type of social deficit that ranges from a lack of inclination to relate to extreme difficulty with the mechanics of social interactions, a global communication deficit that involves both verbal and nonverbal modes, and a severe cognitive deficit involving concept formation (abstraction) that is combined with an exceptional memory for factual information. These symptoms may vary dramatically in severity, but the basic deficits are identifiable regardless of IQ. Under-recognition of autism is a major problem at all IQs, but especially in patients with IQs above 50. No drugs have been found to significantly improve the core deficits in autism. Antipsychotics should be avoided except for short-term use. Antidepressants, anxiolytics, and anticonvulsants are important in the treatment of depression, affective modulation, situation-related stress, and seizures. Intensive social skills training is assuming a prominent role in behavior modification programs, and success with higher-functioning autistic children suggests that outcome can be improved by intensive training. The neurobiology of autism has also undergone dramatic changes. The psychogenic theories of etiology have been completely invalidated. Autism is now considered to be a neurological disorder resulting from an error in brain development. The precise location and nature of this deficit are still being actively debated and investigated. One theory emphasizes a dysfunction of the limbic system that results in an impairment in the acquisition of information. A second theory proposes a primary role for dysfunction of the cortical association network responsible for the processing of information.

Neuropsychological findings in high-functioning men with infantile autism, residual state

Ten men (ages 18-39) with clear histories of Infantile autism and approximately average verbal and nonverbal intelligence were studied with a comprehensive battery of neuropsychological tests. Comparisons with 10 matched normal controls showed no significant differences in many visuoperceptual or memory skills or in sensory-perceptual or motor skills or their lateralization. Differences seen on language measures were small, but statistically significant. In contrast to this, the autistic group demonstrated dramatic deficits on simple and complex, verbal and nonverbal problem-solving tasks, such as the Wisconsin Card Sorting Test, selected tasks from the Stanford-Binet, and the Trail Making Test. A left-hemisphere hypothesis of autism was not supported, nor was there compelling evidence of any posterior cortical deficit. Results are compatible with frontal-system dysfunction or with more widespread pathology.

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology in autism

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology were examined in 15 healthy men, aged 18 to 39 years, with documented childhood diagnoses of infantile autism, and in 20 healthy age- and sex-matched controls using computerized transverse axial tomography (CT). Nine patients were of approximately average intelligence, 3 showed specific language impairments, and 3 were mentally retarded. No significant group differences were seen in the distributions of frontal or posterior asymmetries of width or petalia. No subject showed evidence of cerebellar atrophy or an enlarged fourth ventricle. These results fail to support a hypothesis of unusual hemispheric asymmetry or macroscopic abnormalities of the posterior fossa in autism.

Selective subcortical abnormalities in autism

Nine physically healthy, adult autistic men, with normal or near normal intelligence, and 13 healthy male controls were examined in a CT brain scan study. CT scans were analysed with a fully automated computer-assisted program, and regional brain radiodensities were measured with careful attention to artefacts. Autistic patients revealed significantly larger third, but not lateral, ventricular size and significantly lower mean caudate, but equivalent mean frontal and thalamic, radiodensities compared to controls. The sizes of the Sylvian fissures and interhemispheric fissure were equivalent between groups. The findings are consistent with selective subcortical abnormalities in autism.

Midsagittal magnetic resonance imaging of autism

Since recent reports suggest structural brain abnormalities in autistic patients, we analysed magnetic resonance imaging (MRI) scans of autistic children. Planimetric measurements were done on midsagittal MRI scans, produced with a 0.5 T superconducting magnet. Scans of 13 'high-level' autistic subjects were compared with 35 control MRI scans, read as anatomically normal by a neuroradiologist. Corpus callosal, fourth ventricular, cerebellar, cerebral, and cranial areas were measured. The fourth ventricle was found to be significantly larger in the autistic group. No other areas in the midsagittal scans differed statistically between groups. Results suggest that structures defining the fourth ventricle are anatomically altered in autistic patients.

Autism and pervasive developmental disorders: concepts and diagnostic issues

The purpose of this report is to bring up to date available information on the defining features and diagnostic issues relating to autism and related disorders. We review the validity of the syndrome based on our last review (Rutter, 1978; Schopler, 1978). Subsequent data have produced refinement in our understanding of both diagnostic criteria and the nature of the basic deficit. Controversies over both the boundaries and the heterogeneity within the autism syndrome are evaluated according to available evidence. Diagnostic rating instruments for expediting systematic sample selection are critiqued, and leads for new research directions are suggested.

Biological and neuropsychological approaches to childhood autism

There is growing conviction that childhood autism is a biologically based disorder. The evidence that has accrued in a variety of areas pertaining to biological abnormality in autism suggests that, with the possible exception of genetic factors, very few data are available that illuminate the autistic disorder specifically. Neurological models which might be useful in guiding further research are discussed and reasons for the slow progress in this important aspect of the study of autism are identified.

The organic etiology of infantile autism: a critical review of the literature

Various theories have been provided in the literature regarding the etiology of infantile autism. It seems that the biological causation dominates the thinking of mental health practitioners and researchers irrespective of discipline. Areas of research include the following: neuropathological studies of the brain, autopsies, electroencephalograms, epileptic seizures, brain lateralization, studies in asymmetry; neurochemistry; genetics; and pre-, peri- and postnatal factors. A critical analysis of these studies has indicated that the evidence of organic factors tends to be rather weak and furthermore has been found to be contradictory. It is felt that the major problem lies in the fact that a large number of investigators include in their sampling children with various mental and physical disabilities and label them autistic. In general, there seems to be little information regarding the selection and little background information is offered on these children. It is suggested that a standardized and world wide diagnostic system be constructed which will provide objective etiological results.

Asperger's syndrome and recurrent psychosis--a case study

A 14-year-old boy with mild mental retardation and behavioral features suggestive of the so called Asperger's syndrome is described. From the age of 8 years he has had recurrent episodes of lethargy. At the onset of puberty these episodes took on a more dramatic form and became more reminiscent of cycloid/manic-depressive psychosis. There is a family history of manic-depressive disorder. Neurobiological links with and differences from the syndrome of infantile autism were found. It is suggested that there is still too little evidence clearly to single out the entity of Asperger's syndrome from the spectrum of autistic syndromes.

Autistic children's hand preferences: results from an epidemiological study of infantile autism

Twenty-six autistic children, constituting a total population sample of children diagnosed in accordance with Rutter's criteria as suffering from infantile autism, were assessed with regard to handedness and certain associated factors. They were compared with 52 age-, sex-, and IQ-matched controls. Sixty-two percent of the autistic children were non-right-handed compared with 37% of the controls. Left-handedness in autism was associated with an abundance of delayed echolalia. Heredity for left-handedness in some cases, and assumed brain damage and immature patterns of lateralization in others, were considered the cause of non-right-handedness in the autistic children. Computed tomographic (CT) brain scans and other neurobiological examinations did not provide evidence indicating clear-cut unilateral left hemisphere dysfunction in autism. Rather, a slight trend in the opposite direction (i.e., an association with right hemisphere dysfunction) was seen in the left-handed autistic children. The result points toward the need for further studies of handedness in autism.