Eric London

Stereological study of the neuronal number and volume of 38 brain subdivisions of subjects diagnosed with autism reveals significant alterations restricted to the striatum, amygdala and cerebellum

IntroductionA total of 38 brain cytoarchitectonic subdivisions, representing subcortical and cortical structures, cerebellum, and brainstem, were examined in 4- to 60-year-old subjects diagnosed with autism and control subjects (a) to detect a global pattern of developmental abnormalities and (b) to establish whether the function of developmentally modified structures matches the behavioral alterations that are diagnostic for autism. The volume of cytoarchitectonic subdivisions, neuronal numerical density, and total number of neurons per region of interest were determined in 14 subjects with autism and 14 age-matched controls by using unbiased stereological methods.ResultsThe study revealed that significant differences between the group of subjects with autism and control groups are limited to a few brain regions, including the cerebellum and some striatum and amygdala subdivisions. In the group of individuals with autism, the total number and numerical density of Purkinje cells in the cerebellum were reduced by 25% and 24%, respectively. In the amygdala, significant reduction of neuronal density was limited to the lateral nucleus (by 12%). Another sign of the topographic selectivity of developmental alterations in the brain of individuals with autism was an increase in the volumes of the caudate nucleus and nucleus accumbens by 22% and 34%, respectively, and the reduced numerical density of neurons in the nucleus accumbens and putamen by 15% and 13%, respectively.ConclusionsThe observed pattern of developmental alterations in the cerebellum, amygdala and striatum is consistent with the results of magnetic resonance imaging studies and their clinical correlations, and of some morphometric studies that indicate that detected abnormalities may contribute to the social and communication deficits, and repetitive and stereotypical behaviors observed in individuals with autism.

Differences Between the Pattern of Developmental Abnormalities in Autism Associated with Duplications 15q11.2-q13 and Idiopathic Autism

Abstract The purposes of this study were to identify differences in patterns of developmental abnormalities between the brains of individuals with autism of unknown etiology and those of individuals with duplications of chromosome 15q11.2-q13 (dup[15]) and autism andto identify alterations that may contribute to seizures and sudden death in the latter. Brains of 9 subjects with dup(15), 10 with idiopathic autism, and 7controls were examined. In the dup(15) cohort, 7subjects (78%) had autism, 7 (78%) had seizures, and 6 (67%) hadexperienced sudden unexplained death. Subjects with dup(15) autism were microcephalic, with mean brain weights 300 g less (1,177 g) than those of subjects with idiopathic autism (1,477 g; p<0.001). Heterotopias in the alveus, CA4, and dentate gyrus and dysplasia in the dentate gyrus were detected in 89% of dup(15) autism cases but in only 10% of idiopathic autism cases (p < 0.001). By contrast, cerebral cortex dysplasia was detected in 50% of subjectswith idiopathic autism and in no dup(15) autism cases (p<0.04). The different spectrum and higher prevalence of developmental neuropathologic findings in the dup(15) cohort than in cases with idiopathic autism may contribute to the high risk of early onset of seizures and sudden death.

Abnormal Intracellular Accumulation and Extracellular Aβ Deposition in Idiopathic and Dup15q11.2-q13 Autism Spectrum Disorders

Background It has been shown that amyloid ß (Aβ), a product of proteolytic cleavage of the amyloid β precursor protein (APP), accumulates in neuronal cytoplasm in non-affected individuals in a cell type–specific amount. Methodology/Principal Findings In the present study, we found that the percentage of amyloid-positive neurons increases in subjects diagnosed with idiopathic autism and subjects diagnosed with duplication 15q11.2-q13 (dup15) and autism spectrum disorder (ASD). In spite of interindividual differences within each examined group, levels of intraneuronal Aβ load were significantly greater in the dup(15) autism group than in either the control or the idiopathic autism group in 11 of 12 examined regions (p<0.0001 for all comparisons; Kruskall-Wallis test). In eight regions, intraneuronal Aβ load differed significantly between idiopathic autism and control groups (p<0.0001). The intraneuronal Aβ was mainly N-terminally truncated. Increased intraneuronal accumulation of Aβ17–40/42 in children and adults suggests a life-long enhancement of APP processing with α-secretase in autistic subjects. Aβ accumulation in neuronal endosomes, autophagic vacuoles, Lamp1-positive lysosomes and lipofuscin, as revealed by confocal microscopy, indicates that products of enhanced α-secretase processing accumulate in organelles involved in proteolysis and storage of metabolic remnants. Diffuse plaques containing Aβ1–40/42 detected in three subjects with ASD, 39 to 52 years of age, suggest that there is an age-associated risk of alterations of APP processing with an intraneuronal accumulation of a short form of Aβ and an extracellular deposition of full-length Aβ in nonfibrillar plaques. Conclusions/Significance The higher prevalence of excessive Aβ accumulation in neurons in individuals with early onset of intractable seizures, and with a high risk of sudden unexpected death in epilepsy in autistic subjects with dup(15) compared to subjects with idiopathic ASD, supports the concept of mechanistic and functional links between autism, epilepsy and alterations of APP processing leading to neuronal and astrocytic Aβ accumulation and diffuse plaque formation.

Periventricular lucencies in the CT scans of aged and demented patients

The ability of clinicians to distinguish between Alzheimer’s disease and multiinfarct dementia is problematic. The only evaluation instrument that has achieved widespread acceptance for the differential diagnosis of these interrelated dementing disorders is the ischemic scale, as described by Hachinski et al. (1974), or its modification as reported by Rosen et al. ( 1979). Recently, Liston and La Rue (1983a,b) have strongly suggested that there is a lack of solid clinical or pathological evidence to support the clinical differentiation between the two illnesses. As clinical and research interest in dementing illnesses has increased, the importance of this differential diagnosis has also increased. The computed tomography (CT) scan has become an indispensable tool for studying the brain and brain diseases and is routinely performed as part of a dementia work-up. Its main value is in uncovering secondary causes of dementia, such as tumor or hydrocephalus. whereas its value in diagnosing primary dementias is limited. The traditionally studied measures of ventricular size and cortical sulcal prominence have

Clinicopathological Stratification of Idiopathic Autism and Autism with 15q11.2-q13 Duplications

Postmortem studies of brains of individuals with idiopathic autism and 15q11.2–q13 duplications autism (dup(15)) identify a cluster of neuropathological features differentiating these cohorts. They show a need for both reclassification of autism according to etiology, clinical presentation and neuropathology, and a commonality of clinical and neuropathological traits justifying autism diagnosis. The features differentiating these cohorts include: (a) maternal origin in patients with dup(15); (b) autism in 78% of subjects; (c) more severe clinical phenotypes, with intellectual deficit (100%), early-onset of severe or intractable seizures in 78% of subjects, and increased prevalence (up to 67%) of sudden unexplained death; (d) high prevalence of microcephaly, with mean brain weight 300g less than in idiopathic autism; (e) several-fold increase in the number of developmental abnormalities, including defects of migration and dysplastic changes, especially numerous in the hippocampal formation; and (f) significant increase in the intraneuronal amyloid load, reflecting enhanced amyloid-β precursor protein processing with α-secretase.

Introduction to Neuropathology

Neuropathology is the study of nervous system tissue in terms of either macro- or microscopic alterations. In this chapter we will concentrate on those microscopic alterations at the cellular (e.g., regressive changes, lipofuscin accumulation) and tissue level (e.g., necrosis) that have been variously claimed to be of relevance to autism. The discussions will draw upon the perspective of the author as to their adequacy for postmortem research. Commentaries by senior investigators will discuss the value of neuropathological studies, especially as compared to other research endeavors.