Language predictors of autism spectrum disorder in young children with tuberous sclerosis complex

BACKGROUND

Epilepsy has previously been implicated in the development of autism spectrum disorder (ASD) in the setting of tuberous sclerosis complex (TSC). However, the role of language in this relationship is unclear, and the specific relationship between ASD, epilepsy, and language development in this population has not been well-studied.

OBJECTIVES

The objectives the study were to identify the role of early language in subsequent development of ASD, evaluate the impact of epilepsy as a covariate on language development, and evaluate the relationship between epilepsy, language development, and development of ASD.

METHODS

This study included 154 children ages 3-36 months with TSC who were enrolled in the TSC Autism Center of Excellence Research Network (TACERN), a multicenter, prospective observational study to identify biomarkers of ASD. Developmental and autism-specific assessments were administered longitudinally. Appropriate variables from the Mullen Scales of Early Learning (MSEL), Vineland Adaptive Behavior Scales, 2nd Edition (VABS-II), and Preschool Language Scales, 5th Edition (PLS-5) were used to assess patients' language skills. At 36 months, clinical best estimate, which was based on clinical assessment and observation, was used to determine a diagnosis of ASD.

RESULTS

By 12 months, all language variables on the MSEL, PLS-5, and VABS-II significantly predicted an ASD diagnosis at 36 months. Age at seizure onset was associated with language scores in that later seizure onset was associated with improved language scores on the MSEL, VABS-II, and PLS-5. Seizure onset prior to 6 months was associated with a diagnosis of ASD at 36 months. Higher seizure frequency negatively correlated with language scores at 12 months and beyond. Higher seizure frequency was also associated with an ASD diagnosis at 36 months. When looking at the relationship between epilepsy, language, and ASD diagnosis, by 18 months, language scores were more associated with a later ASD diagnosis at 36 months compared with age at seizure onset, which was a better predictor of later ASD diagnosis earlier in development.

CONCLUSION

Analysis of language variables and epilepsy characteristics from 6 to 36 months and ASD diagnosis at 36 months revealed significant relationships between all three variables. While the direction of these relationships needs further research, epilepsy, language, and the development of ASD are integrally related in young children with TSC.

Utility of the Autism Observation Scale for Infants in Early Identification of Autism in Tuberous Sclerosis Complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a genetic disorder with high prevalence of associated autism spectrum disorder (ASD). Our primary objectives were to determine early predictors of autism risk to identify children with TSC in most need of early interventions. The Autism Observation Scale for Infants (AOSI) was evaluated as a measure of ASD-associated behaviors in infants with TSC at age 12 months and its ability to predict ASD at 24 months.

METHODS

Children ages 0 to 36 months with TSC were enrolled in the TSC Autism Center of Excellence Research Network (TACERN), a multicenter, prospective observational study to identify biomarkers of ASD. The AOSI was administered at age 12 months and the Autism Diagnostic Observation Schedule-2 (ADOS-2) and Autism Diagnostic Interview-Revised (ADI-R) at 24 months. Developmental functioning was assessed using the Mullen Scales of Early Learning. Children were classified as ASD or non-ASD according to the ADOS-2.

RESULTS

Analysis included 79 children who had been administered the AOSI at 12 months and ADOS-2 and ADI-R at 24 months. The ASD group had a mean AOSI total score at 12 months significantly higher than the non-ASD group (11.8 ± 7.4 vs 6.3 ± 4.7; P < 0.001). An AOSI total score cutoff of 13 provided a specificity of 0.89 to detect ASD with the ADOS-2. AOSI total score at 12 months was similarly associated with exceeding cutoff scores on the ADI-R.

CONCLUSIONS

The AOSI is a useful clinical tool in determining which infants with TSC are at increased risk for developing ASD.

Age at stroke determines post-stroke language lateralization

PURPOSE

To determine how age at the time of left middle cerebral artery stroke affects language lateralization in a combined sample of subjects with perinatal, childhood, and adult stroke.

METHODS

19 participants who had perinatal stroke (<1 month of age), 32 with later stroke, and 51 sex-/age-matched healthy controls (HCs) received fMRI of language using verb generation task (VGT).

RESULTS

Percent lesion volumes were not different between groups (perinatal vs. late stroke) when taking brain volume into account (p = 0.084). Perinatal stroke group showed bilateral signal increases compared to more left-lateralized signals in matched HCs; late stroke group and HCs both showed left-hemispheric signal increases. LIs in the stroke groups were consistently more bilateral than in HCs (all p < 0.008) except for the late group's posterior LI (p = 0.080). There was greater proportion of leftward language lateralization in HCs compared to their respective stroke groups (78.9% vs. 31.6% in perinatal; 87.5% vs. 59.4% in late stroke; p = 0.004) and a larger proportion of leftward lateralization in late compared to perinatal stroke (p = 0.039). The age of stroke occurrence showed significant positive associations with global and frontal LI (both p ≤ 0.007).

CONCLUSION

As expected, the age of stroke occurrence affects subsequent verb generation lateralization. Greater cortical plasticity is observed in earlier stroke while later stroke is associated with reliance on the repair of the previously damaged left-hemispheric networks.

Functional magnetic resonance imaging of story listening in adolescents and young adults with Down syndrome: evidence for atypical neurodevelopment

BACKGROUND

Previous studies have documented differences in neural activation during language processing in individuals with Down syndrome (DS) in comparison with typically developing individuals matched for chronological age. This study used functional magnetic resonance imaging (fMRI) to compare activation during language processing in young adults with DS to typically developing comparison groups matched for chronological age or mental age. We hypothesised that the pattern of neural activation in the DS cohort would differ when compared with both typically developing cohorts.

METHOD

Eleven persons with DS (mean chronological age = 18.3; developmental age range = 4-6 years) and two groups of typically developing individuals matched for chronological (n = 13; mean age = 18.3 years) and developmental (mental) age (n = 12; chronological age range = 4-6 years) completed fMRI scanning during a passive story listening paradigm. Random effects group comparisons were conducted on individual maps of the contrast between activation (story listening) and rest (tone presentation) conditions.

RESULTS

Robust activation was seen in typically developing groups in regions associated with processing auditory information, including bilateral superior and middle temporal lobe gyri. In contrast, the DS cohort demonstrated atypical spatial distribution of activation in midline frontal and posterior cingulate regions when compared with both typically developing control groups. Random effects group analyses documented reduced magnitude of activation in the DS cohort when compared with both control groups.

CONCLUSIONS

Activation in the DS group differed significantly in magnitude and spatial extent when compared with chronological and mental age-matched typically developing control groups during a story listening task. Results provide additional support for an atypical pattern of functional organisation for language processing in this population.

Academic problems in children with seizures: relationships with neuropsychological functioning and family variables during the 3 years after onset

OBJECTIVES

Children with long-standing epilepsy have a significantly increased risk of academic underachievement compared with healthy controls. We prospectively followed children from seizure onset to assess the relationship between change in neuropsychological functioning and change in academic achievement and to explore the risk and protective moderating effects of demographic, seizure, and family variables.

METHODS

As part of a larger study, neuropsychological and academic data were collected at both baseline and 36 months for 219 children 6-14 years of age with seizures. Prior factor analysis of results from a battery of well-standardized neuropsychological tests yielded four factors: language, processing speed, attention/executive/construction, and verbal memory/learning. Academic achievement was measured with the Woodcock-Johnson Revised Achievement Test Battery. Correlation coefficients and linear mixed models were used for analysis.

RESULTS

The reading and math scores of children with seizures and siblings did not differ at baseline, but children with seizures had lower scores than siblings at 36 months. Writing scores were significantly lower for affected children than siblings at both times. Among children with seizures, there were positive correlations between neuropsychological functioning and academic achievement at baseline and 36 months. Changes in language and in verbal memory/learning were positively correlated with change in reading achievement (r = 0.25 and r = 0.17, respectively). Age at onset moderated the association between change in neuropsychological functioning and change in reading and writing achievement (P ≤ 0.006), with stronger relationships among younger children (β = 0.25-0.44). The association between change in language and change in writing achievement was moderated by caregiver anxiety (P = 0.04; stronger for more anxious parents, β = 0.40), and the association between change in processing speed and change in math achievement was moderated by etiology (P = 0.02; stronger for symptomatic/cryptogenic vs idiopathic, β = 0.29). Gender and other family variables did not have significant moderating effects.

CONCLUSIONS

Changes in neuropsychological function were associated with changes in academic achievement following onset of seizures, with risk factors being younger age at onset, lower caregiver education, high parental anxiety, and symptomatic/cryptogenic etiology. Academic performance should be closely monitored in children with early-onset seizures.

Neuropsychological status at seizure onset in children: risk factors for early cognitive deficits

OBJECTIVE

This large, prospective, community-based study characterized neuropsychological functioning and academic achievement at the time of the first recognized seizure and identified risk factors for cognitive deficits.

METHODS

We compared 282 children (ages 6-14 years, IQ > or =70) with a first recognized seizure to 147 healthy siblings on a battery of well-standardized and widely used neuropsychological and academic achievement tests and examined relationships with demographic and clinical variables.

RESULTS

In this intellectually normal cohort, 27% with just one seizure and up to 40% of those with risk factors exhibited neuropsychological deficits at or near onset. Risk factors associated with neuropsychological deficits included multiple seizures (i.e., second unprovoked seizure; odds ratio [OR] = 1.96), use of antiepileptic drugs (OR = 2.27), symptomatic/cryptogenic etiology (OR = 2.15), and epileptiform activity on the initial EEG (OR = 1.90); a child with all 4 risks is 3.00 times more likely than healthy siblings to experience neuropsychological deficits by the first clinic visit. Absence epilepsy carried increased odds for neuropsychological impairment (OR = 2.00).

CONCLUSIONS

A subgroup of intellectually normal children with seizures showed neuropsychological deficits at onset. Academic achievement was unaffected, suggesting that there is a window early in the disorder for intervention to ameliorate the impact on school performance. Therefore, the risk factors identified here (especially if multiple risks are present) warrant swift referral for neuropsychological evaluation early in the course of the condition.

Magnetic resonance imaging (MRI) and electroencephalographic (EEG) findings in a cohort of normal children with newly diagnosed seizures

In the initial assessment of children with new-onset seizures, the suggestion that electroencephalography (EEG) should be standard and that magnetic resonance imaging (MRI) should be optional has been questioned. The purposes of this study were to (1) describe the frequency of EEG and MRI abnormalities and (2) explore relationships between MRI and EEG findings to determine their relevance in the assessment of children with new-onset seizures who are otherwise developing normally. As part of an ongoing, prospective study of children with new-onset seizures, we studied 181 children (90 girls and 91 boys). Children were entered into the study within 3 months of their first-recognized seizure. The association between EEG and MRI abnormalities was explored using a chi-square test. Abnormal MRI findings were found in 32.6% (n = 59) of the sample. The EEG and MRI results agreed with respect to classification into normal or abnormal in 37% (n = 67). Of the 50 children with a normal EEG, however, 21 (42%) were found to have an abnormal MRI. We found an unexpectedly high frequency of imaging abnormalities in our sample of otherwise normal children, although the significance of these findings is not clear. Follow-up of these patients will help us interpret the importance of the abnormalities. Despite our relatively small sample, however, our findings indicate that a normal EEG does not reliably predict a normal MRI in children with first seizures.

Functional magnetic resonance imaging reveals atypical language organization in children following perinatal left middle cerebral artery stroke

We used verb generation and story listening tasks during fMRI to study language organization in children (7, 9 and 12 years old) with perinatal left MCA infarctions. Healthy, age-matched comparison children (n = 39) showed activation in left Broca's area during the verb generation task; in contrast, stroke subjects showed activation either bilaterally or in the right hemisphere homologue during both tasks. In Wernicke's area, comparison subjects showed left lateralization (verb generation) and bilateral activation (L > R) (story listening). Stroke subjects instead showed bilateral or right lateralization (verb generation) and bilateral activation (R > L) (story listening). Language is distributed atypically in children with perinatal left hemisphere stroke.

BOLD fMRI signal increases with age in selected brain regions in children

To determine whether the BOLD signal used in fMRI is age dependent in childhood, 332 healthy children (age 4.9-18.9 years) performed tasks in a periodic block design during 3 T fMRI: (1) a verb generation task interleaved with a finger tapping task; (2) a word-picture matching task interleaved with an image discrimination task. Significant correlations between percent signal change in BOLD effect and age occurred in left Broca's, middle frontal, Wernicke's, and inferior parietal regions, and anterior cingulate during the verb generation task; in precentral, postcentral, middle frontal, supplementary motor, and precuneus regions during the finger tapping task; and in bilateral lingula gyri during the word-picture matching task. Thus, BOLD effect increases with age in children during sensorimotor and language tasks.

Practical aspects of conducting large-scale functional magnetic resonance imaging studies in children

The potential benefits of functional magnetic resonance imaging (MRI) for the investigation of normal development have been limited by difficulties in its use with children. We describe the practical aspects, including failure rates, involved in conducting large-scale functional MRI studies with normal children. Two hundred and nine healthy children between the ages of 5 and 18 years participated in a functional MRI study of language development. Reliable activation maps were obtained across the age range. Younger children had significantly higher failure rates than older children and adolescents. It is concluded that it is feasible to conduct large-scale functional MRI studies of children as young as 5 years old. These findings can be used by other research groups to guide study design and plans for recruitment of young subjects.

Supratentorial tuber location and autism in tuberous sclerosis complex

The high rate of autism in tuberous sclerosis complex provides an opportunity to study the pathogenesis of autism. This study investigated the relationship between a DSM-IV diagnosis of autism and tuber location in a sample of 50 individuals with tuberous sclerosis complex. Chi-square analyses revealed no differences between individuals with autism (n = 15) and those without autism (n = 35) on the occurrence of tubers in the right or left frontal, occipital, parietal, or temporal regions. There were no differences between the two groups in the occurrence of tubers in subcortical or cortical regions. In the largest sample to date, these results fail to support the hypothesis that supratentorial tuber location is a marker for autism.