13.1 DISTINCT NEURAL UNDERPINNINGS FOR AUTISM SPECTRUM DISORDER AND ADHD

Abstract

Individuals with autism spectrum disorder (ASD) suffer from significantly higher rates of psychiatric comorbidities compared to typically developing populations. Novel neuroimaging modalities may offer a unique way to clarify the neural underpinnings associated with ASD and other common coexisting disorders. The purpose of this talk is to examine the neurochemical and neural connectivity profile in youth with ASD with and without associated psychopathology using the advanced neuroimaging techniques of proton magnetic resonance spectroscopic (1HMRS) and diffusion tensor imaging (DTI). Our presentation will focus on 2 neuroimaging studies: 1) an 1HMRS imaging study to examine brain neurotransmitter glutamate activity in the pregenual anterior cingulate cortex (pACC) in youth with ASD (N = 37) with and without emotional dysregulation (ED); and 2) a DTI study to examine the neural structural connectivity profile of ADHD in youth with and without ASD (N: ASD = 15, ADHD = 16). The results of the 1HMRS study show that pACC glutamate activity was significantly higher in youth with ASD vs age- and sex-matched healthy controls (95.5 ±14.6 vs 76.6 ±17.7; p < 0.001, MD: –18.8 ± 33.9; ED: –1.21 [–1.84 to –0.57]). The pACC glutamate activity was additionally significantly higher in the presence of ED (p = 0.005). The pACC glutamate activity positively correlated with the severity of ASD (p = 0.002; r = 0.5) and ED (p = 0.05; r = 0.6). Results of the DTI study revealed that the dorsal brain aberrant neural connectivity profile observed with ADHD was also observed with ADHD in youth with ASD. Abnormally high brain glutamate activity was observed as a common neural underpinning between ASD and ED. Furthermore, the neural pathway abnormality associated with ADHD is distinctly expressed in youth with ASD who have ADHD. These results suggest that novel neuroimaging modalities may be able to help elucidate the neural underpinnings of ASD and other commonly co-occurring psychopathologies.