Computed tomographic brain scanning in four neuropsychiatric disorders of childhood

Autism research and services for young children: history, progress and challenges

For three decades after Leo Kanner's first clinical description, research progress in understanding and treating autism was minimal but since the late 1960s the growth of autism discoveries has been exponential, with a remarkable number of new findings published over the past two decades, in particular. These advances were made possible first by the discovery and dissemination of early intensive behavioural intervention (EIBI) for young children with autism that created the impetus for earlier accurate diagnosis. Other factors influencing the rapid growth in autism research were the first accepted diagnostic test for autism, the Autism Diagnostic Interview and Observation Schedule (ADI and ADOS). Developments in brain imaging and genetic technology combined to create a fuller understanding of the heterogeneity of autism, its multiple aetiologies, very early onset and course, and strategies for treatment. For a significant proportion of children with autism, it appears EIBI may be capable of promoting brain connectivity in specific cerebral areas, which is one of autism's underlying challenges. Disagreements about the most appropriate early intervention approach between developmental and behavioural psychologists have been unproductive and not contributed to advancing the field. Naturalistic behavioural and structured discrete trial methods are being integrated with developmental strategies with promising outcomes. Over these past 30 years, young people with autism have gone from receiving essentially no proactive treatment, resulting in lives languishing in institutions, to today, when half of children receiving EIBI treatment subsequently participate in regular classrooms alongside their peers. The future has entirely changed for young people with autism. Autism has become an eminently treatable condition. The time is overdue to set aside philosophical quarrels regarding theories of child development and apply what we know for the benefit of children with autism and their families.

Volumetric assessment of cerebral asymmetries in dogs

In the present study we quantified volumetric brain asymmetries from computed tomography (CT) scans in 12 healthy dogs, using a semi-automated technique for assessing in vivo structure asymmetry. Volumetric assessment of asymmetrical cerebral lateral ventricle (ALV) was also investigated. Our results showed that seven dogs exhibited a right hemisphere significantly greater than the left, two dogs had a left-greater-than-right hemisphere asymmetry, and finally two dogs displayed no significant brain volumetric asymmetry. This right-biased hemispheric asymmetry supports data reported previously using post-mortem morphological studies in both dogs and other mammalian species.

Three-dimensional mapping of the lateral ventricles in autism

In this study, a computational mapping technique was used to examine the three-dimensional profile of the lateral ventricles in autism. T1-weighted three-dimensional magnetic resonance images of the brain were acquired from 20 males with autism (age: 10.1+/-3.5 years) and 22 male control subjects (age: 10.7+/-2.5 years). The lateral ventricles were delineated manually and ventricular volumes were compared between the two groups. Ventricular traces were also converted into statistical three-dimensional maps, based on anatomical surface meshes. These maps were used to visualize regional morphological differences in the thickness of the lateral ventricles between patients and controls. Although ventricular volumes measured using traditional methods did not differ significantly between groups, statistical surface maps revealed subtle, highly localized reductions in ventricular size in patients with autism in the left frontal and occipital horns. These localized reductions in the lateral ventricles may result from exaggerated brain growth early in life.

Spect Findings in Children with Specific Language Impairment

Findings from 99mTc-HMPAO SPECT measurements at rest in a group of 19 school-age children with specific language impairment (SLI) were compared to a group of 12 children with attention-deficit hyperactivity disorder (ADHD). The regional cerebral blood flow (CBF) distributions were different in the two groups. Children with SLI showed significantly lower CBF values in the right parietal region and in the subcortical region compared to the ADHD group. In addition, the SLI group had symmetric CBF distributions in the left and right temporal regions, whereas the ADHD group showed the usual asymmetry with left-sided hemispheric predominance in the temporal regions. The findings give further evidence for anomalous neurodevelopment with deviant hemispheric lateralization as an important factor in the aetiology of SLI. They also point to the role of subcortical structures in language impairment in childhood. Earlier focus on cortical structures in SLI research needs to be widened to include subcortical regions as well.

Neurobiology of Tourette's syndrome: concepts of neuroanatomic localization and neurochemical abnormalities

Despite a preponderance of evidence suggesting an organic rather than psychogenic origin for Tourette syndrome, the precise neurobiological abnormality remains speculative. Neuroanatomically, there is expanding confirmation that cortico-striato-thalamo-cortical pathways represent the site of origin for tics and accompanying neuropsychiatric problems. Pathophysiological hypothesis are generally defined based on involvement of (1) a specific anatomical site (striato-thalamic circuits, striatal compartments), (2) physiologic abnormality (excess thalamic excitation, impaired intracortical inhibition), or (3) involvement of a specific neurotransmitter or synaptic component. This review provides information essential for understanding current and future proposals pertaining to the neurobiology of this intriguing disorder.

Neuroimaging in hyperkinetic children and adults: an overview

The application of brain imaging techniques to children with Attention Deficit/Hyperactivity Disorders is reviewed, stressing methodological aspects. Findings are still provisional, but suggest minor structural changes in frontal and candate areas, especially on the right side. Functional studies suggest reduced activation in these and other areas. The techniques do not yet contribute to individual diagnosis.

Functional brain imaging in neuropsychiatric disorders of childhood

This review article presents a summary of the current state-of-the-art of functional brain imaging, with a primary focus on childhood neuropsychiatric disorders. Coverage is emphasized for developments that appear to be of current or potential future importance for the child neurologist and related pediatric specialist, and also from the perspective of the developmental neuroscientist. Emphasis is placed on the modalities of single photon emission computed tomography (SPECT), positron emission tomography (PET), and both "conventional" and "functional" magnetic resonance imaging, (MRI) including reference to the major new radiopharmaceutical and magnetic resonance-based imaging agents and techniques. The fundamental physicochemical processes underlying such studies are outlined, with citation of sources of more detailed information for the interested reader. A variety of imaging studies are reviewed for selected groups of childhood neuropsychiatric disorders, designed to illustrate the achievements and future promise of these imaging modalities. Areas of concentration are suggested for future imaging research in the field of childhood behavioral disorders, where these methods seem critical to improved understanding of pathogenetic mechanisms, as well as development of more effective treatment strategies.

Neurobiology of Tourette syndrome

This article includes a discussion of approaches designed to determine neuroanatomic localization through the use of physical examination, electrophysiologic and neuroradiographic studies, and neuropathologic evaluations. The author reviews the anatomy, function, and biochemistry of frontal-subcortical circuits. Inferred and direct evidence that supports a disorder of frontal-subcortical circuits in Tourette syndrome is presented. Studies investigating specific neurotransmitters are reviewed.

Executive functions and developmental psychopathology

In this paper, we consider the domain of executive functions (EFs) and their possible role in developmental psychopathologies. We first consider general theoretical and measurement issues involved in studying EFs and then review studies of EFs in four developmental psychopathologies: attention deficit hyperactivity disorder (ADHD), conduct disorder (CD), autism, and Tourette syndrome (TS). Our review reveals that EF deficits are consistently found in both ADHD and autism but not in CD (without ADHD) or in TS. Moreover, both the severity and profile of EF deficits appears to differ across ADHD and autism. Molar EF deficits are more severe in the latter than the former. In the few studies of more specific EF tasks, there are impairments in motor inhibition in ADHD but not in autism, whereas there are impairments in verbal working memory in autism but not ADHD. We close with a discussion of implications for future research.

Neuroimaging in child and adolescent neuropsychiatric disorders

OBJECTIVE

To review the major findings and pathophysiological implications of imaging studies of neuropsychiatric disorders that onset in childhood or adolescence.

METHOD

More than 200 neuroimaging studies were selected for review from Medline searches if the studies concerned developmental neuropsychiatric disorders such as autism, fragile X syndrome, Down syndrome, schizophrenia, obsessive-compulsive disorder, Tourette's syndrome, attention-deficit hyperactivity disorder, and dyslexia.

RESULTS

Disordered central nervous system development may produce evidence of cortical neuronal migration abnormalities in autism, smaller cortical structures in Down syndrome, frontal lobe deficits and larger basal ganglia in schizophrenia, hypoplastic basal ganglia in Tourette's syndrome, aberrancies of the planum temporale in dyslexia, and hypoplastic cerebellar structures in numerous developmental disorders. Normal cerebral asymmetries appear to be disrupted in a number of disorders, including schizophrenia, Tourette's syndrome, attention deficit disorder, and dyslexia.

CONCLUSIONS

Neuroimaging data regarding pathological central nervous system development in childhood are still sparse, and many of the findings in developmental disorders of childhood onset concern the study of adult subjects with those disorders. Nevertheless, imaging modalities previously used only in adults are with increasing frequency being applied to the study of children, which will likely continue to contribute to the understanding of pathological brain structure and function throughout childhood and to the improved treatment of these disorders.

Study of unilateral hemisphere performance in children with developmental dysphasia

Hemisphere specialization for language was studied in 10 children with expressive developmental dysphasia (DD) (mean age 10 years 4 months) submitted to a dichotic listening task (in a word free-recall task and forced-attention task) and a finger tapping/vocalization dual-task paradigm. A nonsense shape dichaptic task was also introduced to control right hemispheric processing. Performances of dysphasic children were compared to those obtained from 15 normal children. The results showed that controls had a right ear advantage in free-recall (words) dichotic listening task and a significant right ear advantage in forced-right-attention task, with a change in ear asymmetry as a consequence of instruction. In the dysphasic group we observed a significant right ear advantage in the free-recall dichotic listening task and no change in ear asymmetry during forced right or forced left condition. Results in time sharing paradigm and nonsense dichaptic task are more difficult to interpret, because there was no interaction between group and condition. These results cannot support a complete left hemisphere dysfunction in developmental dysphasia.

Neurobiological issues in Tourette syndrome

The Tourette syndrome (TS) represents an intriguing disorder that overlaps the clinical fields of neurology and psychiatry. Composed of a spectrum of familial, involuntary motor and vocal tics and co-morbid neuropsychological problems, this disorder has become a model for investigators interested in neurobehavioral research. Although the subject of numerous reports since Tourette's original description in 1885, over the past decade there has been a rapid expansion of knowledge pertaining to the phenomenology of tic syndromes and their associated problems, the role of genetic and environmental factors, and the underlying pathophysiology. The role of frontal-subcortical circuits, dopaminergic neurotransmission, and second messenger systems are highlighted. This report provides a framework for understanding current neurobiological issues in TS.

An artificial neural network analogue of learning in autism

An artificial neural network is simulated that shares formal qualitative similarities with the selective attention and generalization deficits seen in people with autism. The model is based on neuropathological studies which suggest that affected individuals have either too few or too many neuronal connections in various regions of the brain. In simulations where the model was taught to discriminate children with autism from children with mental retardation, having too few simulated neuronal connections led to relatively inferior discrimination of the two groups in a training set and, consequently, relatively inferior generalization of the discrimination to a novel test set. Too many connections produced excellent discrimination but inferior generalization because of overemphasis on details unique to the training set. It is concluded that, within the context of the current model, the neuropathological observations that have been described in the literature are sufficient to explain some of the unique pattern recognition and discrimination learning abilities seen in some people with autism as well as their problems with generalization and concept acquisition. The model generates testable hypotheses that have implications for understanding the pathogenesis, treatment, and phenomenology of autism.

Tourette syndrome: associated symptoms and most disabling features

Four hundred forty-six patients with Tourette Syndrome (TS) and/or their parents completed a 52-item self-report survey about vocal and motor tics, and the frequency of associated co-morbid conditions of aggression, obsessions and compulsions, attentional problems, sleep disturbance, mood disturbance, anxiety, and self-mutilative behaviours which have been frequently reported in the literature on TS. Respondents also responded to an open-ended question regarding the most disabling aspects of TS. Results were analyzed within two age groups; under 18 years of age (N = 245) and 18 years of age or older (N = 177). Tics and associated conditions were the most frequently reported disabling aspect by both age groups. Subjects under age 18, however, reported significantly more frequent problems with hyperactivity, temper control, aggressive behaviours and sleepwalking than adults with TS.

Magnetic resonance imaging in patients with concurrent Tourette's disorder and Asperger's syndrome

OBJECTIVE

The purpose of the study was to examine behavioral/cognitive and neuroradiological features of patients with concurrent Tourette's disorder (TD) and Asperger's syndrome (AS).

METHODS

The authors studied the occurrence of structural brain abnormalities using magnetic resonance imaging (MRI) in seven males with concurrent TD and AS, and in nine age-matched males, who had TD but did not have AS. Both groups were tested with an extensive battery of neurological and psychiatric rating scales and cognitive tests.

RESULTS

Five of the seven patients with TD and AS had developmental brain anomalies. In contrast, normal MRI scans were found in all but one TD patient without AS. Both groups were not significantly different in the severity of motor and phonic tics, obsessionality, depression and anxiety, or in measures of general intelligence, memory, and language function; but patients with TD and AS had a history of more psychiatric hospitalizations, poor academic achievement, more neurological soft signs and appeared more impaired on complex problem-solving and spatial tests than did TD patients without AS.

CONCLUSION

These findings suggest that structural cortical and subcortical abnormalities are more common among individuals with concurrent TD and AS than among sex- and age-matched TD patients without AS. Dysfunction of frontal-subcortical systems may play a role in the pathophysiology of concurrent TD and AS.

Gilles de la Tourette syndrome: a neuropsychiatric disorder

Gilles de la Tourette Syndrome is a neuropsychiatric disorder which manifests with neurological psychological and psychiatric symptoms. Understanding of this complex disorder has grown rapidly in the past 25 years. This paper reviews the current knowledge of biological and psychological factors which interact to produce a variable yet clearly recognisable syndrome. New directions for research are explored. Current literature suggests that despite many gains, much remains to be learned about this disorder.

Tic disorders

This article has provided an approach to patients who present with Tourette's syndrome or other tic disorders. The goals are to clarify each of the problems, to determine whether the major source of distress is related to tics or associated behaviors, and to develop an individualized multimodal treatment program. A valuable source of additional information for physicians, parents, and patients is the voluntary nonprofit Tourette Syndrome Association, 42-40 Bell Blvd, Bayside, NY 11361-9596.

Utility of the head computerized tomography scan in child and adolescent psychiatry

Despite the widespread use of computerized tomography (CT) in child and adolescent psychiatry, studies have not looked at its overall usefulness in a clinical setting. In this report, the authors examined 122 inpatients who had CT scans of the head. Only 27 patients had an abnormal CT scan. None of the patients had a change made in the diagnosis or treatment as a result of the scan findings. The authors suggest that routine CT scans of the head in child and adolescent inpatients is of limited value. In view of the rising costs of medical investigations, and the risk of irradiation to the developing brain, they suggest the need for clear indications for this procedure in clinical child and adolescent psychiatry.

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 posterior fossa in autism

The brainstem-cerebellar circuitry has been implicated in the pathophysiology of autism for several decades. Recent magnetic resonance imaging (MRI) studies of the posterior fossa have reported various abnormalities, the most noteworthy of which has been selective hypoplasia of the neocerebellar vermis. However, these initial MRI studies are limited by problems in both subject and control selection. The present study was undertaken to further investigate these MRI findings and the role of the cerebellum in autism, taking into consideration these methodologic issues. Eighteen high-functioning autistic subjects were recruited and matched with 18 normal controls on the basis of age, gender, IQ, race and socioeconomic status (SES). The midsagittal areas of the cerebellar vermis, vermal lobes, and the fourth ventricle were measured on 3 mm contiguous magnetic resonance images. Mean areas and standard deviations were comparable for all regions of interest and no statistically significant between-group differences were found. These negative findings argue against theories of autism based on gross structural abnormalities of the cerebellum. Previous reports of posterior fossa abnormalities may be related to technical and methodological factors, based on comparison of extant literature and recently available normative data.

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.

The Gilles de la Tourette syndrome: the current status

The Gilles de la Tourette Syndrome is a movement disorder characterised by both motor and vocal (phonic) tics. It was once thought to be rare, and the literature until the 1970s consisted predominantly of case reports, both highlighting the fascinating clinical manifestations and speculating as to their aetiology. Many areas of GTS are under investigation, including the neurology, psychopathology, neurophysiology, biochemistry, and genetics. This review briefly considers early descriptions of GTS as well as current research, highlighting the areas of agreement and controversy.

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.