Changes in the development of striatum are involved in repetitive behavior in autism.

BACKGROUND: Repetitive behavior is a core feature of autism and has been linked to differences in striatum. In addition, the brain changes associated with autism appear to vary with age. However, most studies investigating striatal differences in autism are cross-sectional, limiting inferences on development. In this study, we set out to 1) investigate striatal development in autism, using a longitudinal design; and 2) examine the relationship between striatal development and repetitive behavior. METHODS: We acquired longitudinal structural magnetic resonance imaging scans from 86 individuals (49 children with autism, 37 matched control subjects). Each individual was scanned twice, with a mean scan interval time of 2.4 years. Mean age was 9.9 years at time 1 and 12.3 years at time 2. Striatal structures were traced manually with high reliability. Multivariate analyses of variance were used to investigate differences in brain development between diagnostic groups. To examine the relationship with behavior, correlations between changes in brain volumes and clinical measures were calculated. RESULTS: Our results showed an increase in the growth rate of striatal structures for individuals with autism compared with control subjects. The effect was specific to caudate nucleus, where growth rate was doubled. Second, faster striatal growth was correlated with more severe repetitive behavior (insistence on sameness) at the preschool age. CONCLUSIONS: This longitudinal study of brain development in autism confirms the involvement of striatum in repetitive behavior. Furthermore, it underscores the significance of brain development in autism, as the severity of repetitive behavior was related to striatal growth, rather than volume per se.

No evidence for structural brain changes in young adolescents at ultra high risk for psychosis.

OBJECTIVE: The onset of psychosis is thought to be preceded by neurodevelopmental changes in the brain. However, the timing of these changes has not been established. We investigated structural brain changes in a sample of young adolescents (12-18 years) at ultra high-risk for psychosis (UHR). METHODS: Structural MRI data from young UHR subjects (n=54) and typically developing, matched controls (n=54) were acquired with a 1.5 Tesla scanner and compared. RESULTS: None of the measures differed between UHR subjects and controls. CONCLUSIONS: Our results do not support the presence of gross neuroanatomical changes in young UHR subjects. This suggests that early changes are too subtle to detect with conventional imaging techniques. Therefore, changes observed in older cohorts may only onset later developmentally or occur secondary to prodromal symptoms.

Changes in the developmental trajectories of striatum in autism.

BACKGROUND: Repetitive and stereotyped behavior has been associated with striatum in various neuropsychiatric disorders. However, striatal involvement has not yet been shown conclusively in autism. Issues include the use of neuroleptic medication and differences in mean age between samples, where conflicting results may reflect differences in developmental stage between samples. The objective was to examine brain development in a homogeneous sample of subjects with high-functioning autism. METHODS: Magnetic resonance measures of brain structure of 188 individuals (99 subjects with high-functioning autism and 89 typically developing, matched control subjects) aged between 6 years and 25 years were compared. Measurements included the volume of brain structures, including striatum, as well as voxel-based assessment of gray matter density. RESULTS: Developmental trajectories of the caudate nucleus, putamen, and nucleus accumbens differed between subjects with autism and control subjects. Results were not accounted for by overall changes in brain volume or neuroleptic medication. The development of the caudate nucleus differed from typical most, as its volume increased with age in autism, while it decreased for control subjects. Voxel-based analysis showed that changes in striatum localized to the head of the caudate nucleus. Overall, caudate nucleus volume was associated with repetitive behavior in autism. CONCLUSIONS: We report changes in striatal development in autism, while caudate volume is associated with repetitive behaviors. This emphasizes the importance of striatum in the etiology of autism, in particular in the development of repetitive behavior that characterizes the disorder.

No differences in MR-based volumetry between 2- and 7-year-old children with autism spectrum disorder and developmental delay.

OBJECTIVE: To study brain volumes in children with ASD as compared to children with a mental retardation or a language delay (developmentally delayed). In addition, to study the association of intellectual functioning on brain volumes in children with ASD or developmental delay. METHODS: Thirty-four children with ASD and 13 developmentally delayed children without ASD, between 2 and 7 years old, matched on age and developmental level, participated in a MRI study. Volumes of cranium, total brain, cerebellum, grey and white matter, ventricles, hippocampus and amygdala were measured. RESULTS: No significant differences in volumes of intracranium, total brain, ventricles, cerebellum, grey or white matter or amygdala and hippocampus between the ASD group and the developmentally delayed group were found. In the developmentally delayed group, a significant correlation (0.73) was found between intellectual functioning and total brain volume after partialling out intracranial volume. In the ASD group, the correlation between intellectual functioning and brain volume corrected for intracranial volume was not significant. CONCLUSION: No evidence was found for overall differences in brain volumes in children with ASD compared to developmentally delayed children between 2 and 7 years. The finding that higher intellectual functioning was not associated with a relative larger brain volume in children with ASD may suggest that a relative enlargement of the brain may not be beneficial to patients with autism.

No evidence for preferential involvement of medial temporal lobe structures in high-functioning autism.

BACKGROUND: Autism is a neurodevelopmental disorder associated with slight increases in brain volume. There has been some suggestion that medial temporal lobe structures may be preferentially involved in this disorder, although results have not always been consistent. Here, we investigate amygdala and hippocampus volumes in medication-naive subjects with high-functioning autism. METHOD: Whole-brain magnetic resonance imaging scans were acquired from 42 patients and 42 closely matched, healthy control subjects. RESULTS: Amygdala volume did not differ significantly between patients and controls. A significant increase in hippocampal volume was proportional to an increase in overall brain volume. CONCLUSIONS: These results argue against preferential involvement of medial temporal lobe structures in autism, at least in high-functioning medication-naive individuals.