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Effects of Early Social-Communicative Intervention on the Brain Activity of Toddlers with ASD: An ERP Study.
There is large consensus that objective and insightful evaluations of autism interventions should include neurophysiological measures.
Objectives:
This randomised controlled trial tests the effects of Project ImPACT, an early parent-run intervention targeting social-communicative skills, on the behaviour and brain activity of toddlers with Autism Spectrum Disorder (ASD).
Methods:
Toddlers with ASD have been randomised to receive either Project ImPACT or treatment as usual (TAU), which does not specifically focus on social-communicative abilities. Researchers involved in data acquisition and analysis were blind to group assignation. Outcome measures include event related potentials (ERPs) in response to standard and deviant voice and non-voice stimuli.
The ImPACT (n=12, 1 girl, mean age: 3.1 ±.6, mean IQ: 62.67 ± 24.42) and TAU groups (n=8, 1 girl, mean age: 3.5 ±.5, mean IQ: 59.38 ± 22.5) were compared at baseline and outcome separately to typically developing (TD) children (n=16, 4 girls, mean age: 3.0 ±.9) in the P1, N2, P3 and N4 time windows. Sample size will increase to n = 20 or higher per group before the INSAR meeting. A 2 X (voice/non-voice standard sound) X 2(voice/non-voice deviant sound) X 2 (group) interaction was tested using permutation-based t-test (n=5000) over differences between levels and between factors. Time was added as a two-level factor when comparing ImPACT and TAU.
Results:
This section highlights the most prominent findings of this study (complete overview in Table 1).
A significant main effect of group was found over N2 mean voltages when comparing the ImPACT group at baseline and the TD group (t(1,26) = 1.849, p = .031), as well as the TAU group at baseline and the TD group (t(1,22) = 1.759, p = .048).
For the ImPACT group, the difference with TD became non-significant after the intervention (t(1,26) = .576, p = .279). For the TAU group, the difference with TD was still significant after the intervention (t(1,22) = 1.937, p = .033). A paired samples t-test within the ImPACT group confirmed the effect of treatment on the N2 component (t(1,11) = 3.256, p =.005), which became less negative (Figure 1).
The differential effect of intervention over the N2 response to deviant stimuli was further supported by the time X group interaction approaching significance when comparing the ImPACT and TAU groups (t(1,18) = 1.412, p = .085).
Exploratory analysis suggests that a larger N2 in children with ASD correlates with worse response to joint attention (r = .442 [.017 767], p =.049). We will further investigate whether the treatment effect on the N2 ERP component is associated with improved response to joint attention.
Conclusions:
Initial group differences, as well as treatment effects, were mostly observed on the N2 ERP component. A larger N2 response at baseline in children with ASD may reflect hypersensitivity to sound change or a more effortful attentional disengagement, with possible repercussions on the children’s social behaviour. These preliminary results suggest a deeper effect of early intervention focused on social-communicative skills training compared to intervention that does not primarily focus on social communicative abilities.