Neuroepileptic correlates of autistic symptomatology in tuberous sclerosis

Reduced minicolumns in the frontal cortex of patients with autism

Cell minicolumns were shown to be narrower in frontal regions in brains of autistic patients compared with controls. This was not found in primary visual cortex. Within the frontal cortex, dorsal and orbital regions displayed the greatest differences while the mesial region showed the least change. We also found that minicolumns in the brain of a 3-year-old autistic child were indistinguishable from those of the autistic adult in two of three frontal regions, in contrast to the control brains. This may have been due to the small size of the columns in the adult autistic brain rather than to an accelerated development. The presence of narrower minicolumns supports the theory that there is an abnormal increase in the number of ontogenetic column units produced in some regions of the autistic brain during corticoneurogenesis.

Medical investigation of children with autistic spectrum disorders

Few well-constructed studies have systematically evaluated medical investigation protocols for children with autistic spectrum disorders. This is in large part due to the heterogeneous nature of the population and changing diagnostic frameworks. This review outlines the studies that have directed investigation strategies to date, and discusses how these might be applied in the clinical situation. The importance of listing the conditions that may be present on the basis of the specific clinical presentation, and using a thorough history and examination to generate a pre-test probability of the target disorders is emphasized if tests are to be useful in directing therapy or broader management approaches.

The prevalence of autistic spectrum disorder in children surveyed in a tertiary care epilepsy clinic

It is well documented that children with autistic spectrum disorder (ASD) have an increased prevalence of seizures; however, studies have not been done to evaluate the prevalence of ASD in children with epilepsy. This comorbidity is important to define as early diagnosis and intervention in some children with ASD has been shown to improve outcome.

METHOD

Children with epilepsy seen in a tertiary care epilepsy clinic were evaluated using validated autism screening questionnaires (ASQ). In addition, questions about sleep-related disorders, behavior, seizure characteristics, antiepileptic agents, and body mass index (BMI) were requested. An attempt was then made to determine if there was a correlation between the factors identified and ASD.

RESULTS

Of the 107 questionnaires returned, 97 ASQ's were properly completed and used in this study. Approximately 32% of children fit the ASQ criteria for having ASD. Most children had not been previously diagnosed. Worst behavior and daytime sleepiness was seen in those at greater risk (p < 0.01). Seizures also occurred earlier (approximately 2 years) in children at risk of having ASD.

CONCLUSION

Though confirmatory diagnostic evaluations are needed, this questionnaire-based study suggests that children with epilepsy are at greater risk of having ASD, and illustrates the need for more clinical vigilance. Behavioral difficulties and daytime sleepiness identified in these children could potentially affect their ability to learn. It is of interest that the age of seizure onset identified in those at greater risk corresponds with the approximate age of regression identified in some children with ASD.

Autistic-spectrum disorders: lessons from neuroimaging

Autistic-spectrum disorder is approximately half as common as schizophrenia but its cause remains unknown. Recent studies have begun to clarify the underlying neuroanatomical abnormalities and brain-behaviour relationships in autism. In the past decade, great advances have been made in our understanding of the neurobiological basis of autism.

The orbitofrontal-amygdala circuit and self-regulation of social-emotional behavior in autism

Individuals with an autistic spectrum disorder are impaired not only in understanding others' mental states, but also in self-regulation of social-emotional behavior. Therefore, a model of the brain in autism must encompass not only those brain systems that subserve social-cognitive and emotional functioning, but also those that subserve the self-regulation of behavior in response to a changing social environment. We present evidence to support the hypothesis that developmental dysfunction of the orbitofrontal-amygdala circuit of the brain is a critical factor in the development of autism and that some of the characteristic deficits of persons with autism in socio-emotional cognition and behavioral self-regulation are related to early dysfunction of different components of this circuit. A secondary hypothesis posits that the degree of intellectual impairment present in individuals with autism is directly related to the integrity of the dorsolateral prefrontal-hippocampal circuit of the brain. Together, these hypotheses have the potential to help explain the neurodevelopmental basis of some of the primary manifestations of autism as well as the heterogeneity of outcomes.

Statistical distribution of blood serotonin as a predictor of early autistic brain abnormalities

BACKGROUND

A wide range of abnormalities has been reported in autistic brains, but these abnormalities may be the result of an earlier underlying developmental alteration that may no longer be evident by the time autism is diagnosed. The most consistent biological finding in autistic individuals has been their statistically elevated levels of 5-hydroxytryptamine (5-HT, serotonin) in blood platelets (platelet hyperserotonemia). The early developmental alteration of the autistic brain and the autistic platelet hyperserotonemia may be caused by the same biological factor expressed in the brain and outside the brain, respectively. Unlike the brain, blood platelets are short-lived and continue to be produced throughout the life span, suggesting that this factor may continue to operate outside the brain years after the brain is formed. The statistical distributions of the platelet 5-HT levels in normal and autistic groups have characteristic features and may contain information about the nature of this yet unidentified factor.

RESULTS

The identity of this factor was studied by using a novel, quantitative approach that was applied to published distributions of the platelet 5-HT levels in normal and autistic groups. It was shown that the published data are consistent with the hypothesis that a factor that interferes with brain development in autism may also regulate the release of 5-HT from gut enterochromaffin cells. Numerical analysis revealed that this factor may be non-functional in autistic individuals.

CONCLUSION

At least some biological factors, the abnormal function of which leads to the development of the autistic brain, may regulate the release of 5-HT from the gut years after birth. If the present model is correct, it will allow future efforts to be focused on a limited number of gene candidates, some of which have not been suspected to be involved in autism (such as the 5-HT4 receptor gene) based on currently available clinical and experimental studies.

Novel treatments for autistic spectrum disorders

In no area of developmental pediatric practice is there more controversy regarding the choice of treatment than related to children with autistic spectrum disorders (ASD). Complementary and alternative medical therapies (CAM) are often elected because they are perceived as treating the cause of symptoms rather than the symptoms themselves. CAM used for autism can be divided by proposed mechanism: immune modulation, gastrointestinal, supplements that affect neurotransmitter function, and nonbiologic intervention. Secretin as a therapy for autism is discussed as an example of how a clinical observation rapidly grew to a widespread treatment before well-designed studies demonstrated absence of effect. The plausibility for behavioral effect was not substantiated by clinical studies. CAM used for treatment of autism is examined in terms of rationale, evidence of efficacy, side effects, and additional commentary. Families and clinicians need access to well-designed clinical evidence to assist them in choice of therapies.

Platelet serotonin concentrations in PKU patients under dietary control and tetrahydrobiopterin treatment

Tetrahydrobiopterin (BH4) supplementation has been applied in PKU treatment, resulting in successful control of blood phenylalanine (Phe) concentrations. We evaluated serotonin status in PKU patients under classical dietary treatment (n = 40) and in a group of 11 PKU patients under BH4 treatment, both during a 6-month period. Platelet serotonin values were significantly lower in PKU patients under dietary treatment when compared with controls. A negative correlation was observed between plasma Phe and platelet serotonin concentrations (r = -0.367, p = 0.017) in PKU patients. Platelet serotonin concentration increased significantly after both 1 and 6 months of BH4 therapy when compared with baseline conditions (Wilcoxon test: p = 0.013 and p = 0.021, respectively), while no differences were observed when comparing plasma Phe concentrations at the different points. Our results indicate that PKU patients under classical treatment have decreased platelet serotonin concentrations, probably owing to continued high Phe values, while BH4 supplementation restored platelet serotonin values.