SUMMARYObjectives: The relative contribution of interictal epileptiform discharges (IEDs) to cognitive dysfunction in comparison with the underlying brain pathology is not yet understood in children with lesional focal epilepsy. Methods: The current study investigated the association of IEDs with intellectual functioning in 103 children with medication-resistant focal epilepsy. Hierarchical multiple regression analyses were used to determine the independent contribution of IED features on intellectual functioning, after controlling for effects of lesional pathology, epilepsy duration, and medication. Exploratory analyses were conducted for language and memory scores as well as academic skills available in a subset of participants. Results: The results reveal that IEDs have a negative association with IQ with independent, additive effects documented for frequent and bilaterally distributed IEDs as well as discharge enhancement in sleep. Left-lateralized IEDs had a prominent effect on verbal intelligence, in excess of the influence of left-sided brain pathology. These effects extended to other cognitive functions, most prominently for sleep-enhanced IEDs to be associated with deficits in expressive and receptive language, reading, spelling and numerical skills. Significance: Overall, IED effects on cognition were of a magnitude similar to lesional influences or drug effects (topiramate use). This study demonstrates an association between IEDs and cognitive dysfunction, independent of the underlying focal brain pathology. KEY WORDS: Focal epilepsy, Children, Interictal epileptiform discharges, Cognition, Intelligence. FULL-LENGTH ORIGINAL RESEARCHEarly onset childhood epilepsy is known to be associated with impaired cognitive development, but the relationship of this to ongoing epileptiform activity remains controversial.1 Interictal epileptiform discharges (IEDs) are sharp waves, spikes, or spike-wave complexes that occur in the absence of observable changes in behavior.2 A direct relationship between IED severity and the degree of short-and long-term cognitive impairment experienced by children with epilepsy has been suggested. 3,4 However, the debate continues as to whether IEDs are mainly an expression of the underlying brain pathology, 4,5 a debate that extends to the question of whether pharmacologic suppression of IEDs is warranted. Current evidence on the possible chronic impact of IEDs on cognition in children derives mainly from studies in patients with nonlesional epilepsy and with low seizure frequency. 3,6,7 Across studies in children with benign rolandic epilepsy (BRE), there is evidence that frequent and multifocal IEDs are associated with cognitive deficits, ranging from general intellectual functions 8 and educational progress 3 to affecting only specific cognitive domains. 6,8,9 There is variability in the extent to which IEDs during sleep are associated with cognition, ranging from negative findings 10 to reporting robust effects on reading and verbal IQ (VIQ).11 A large study of children with p...
Genetic syndrome groups at high risk of autism comorbidity, like Down syndrome and fragile X syndrome, have been presented as useful models for understanding risk and protective factors involved in the emergence of autistic traits. Yet despite reaching clinical thresholds, these 'syndromic' forms of autism appear to differ in significant ways from the idiopathic or 'non-syndromic' autism profile. We explore alternative mechanistic explanations for these differences and propose a developmental interpretation of syndromic autism that takes into account the character of the genetic disorder. This interpretation anticipates syndrome-specific autism phenotypes, since the neurocognitive and behavioural expression of the autism is coloured by syndromically defined atypicalities. To uncover the true nature of comorbidities and of autism per se, we argue that it is key to extend definitions of autism to include the perceptual and neurocognitive characteristics of the disorder and then apply this multilevel conceptualization to the study of syndromic autism profiles.
Highlights Visuospatial orienting efficiency increases with symptom severity in idiopathic ASD. Children with Down syndrome and comorbid ASD display superior search performance. Visuo-spatial orienting ability and visual search performance appears unrelated.
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