Cerebral [18F]-FDOPA Uptake in Autism Spectrum Disorder and Its Association with Autistic Traits

Abstract

Dopaminergic signaling is believed to be related to autistic traits. We conducted an exploratory 3,4-dihydroxy-6-[¹⁸F]-fluoro-L-phenylalanine positron emission tomography/computed tomography ([¹⁸F]-FDOPA PET/CT) study, to examine cerebral [¹⁸F]-FDOPA influx constant (k_i^cer min^-1), reflecting predominantly striatal dopamine synthesis capacity and a mixed monoaminergic innervation in extrastriatal neurons, in 44 adults diagnosed with autism spectrum disorder (ASD) and 22 controls, aged 18 to 30 years. Autistic traits were assessed with the Autism Spectrum Quotient (AQ). Region-of-interest and voxel-based analyses showed no statistically significant differences in k_i^cer between autistic adults and controls. In autistic adults, striatal k_i^cer was significantly, negatively associated with AQ attention to detail subscale scores, although Bayesian analyses did not support this finding. In conclusion, among autistic adults, specific autistic traits can be associated with reduced striatal dopamine synthesis capacity. However, replication of this finding is necessary.

Keywords: [18F]-FDOPA; autism spectrum disorder; autistic traits; dopamine; monoamine; positron emission tomography.

Figure 1

Axial (left), coronal (middle), and sagittal (right) view of the mean cerebral [¹⁸F]-FDOPA uptake (k_i^cer min⁻¹; unadjusted and unsmoothed) in (A) adults with autism spectrum disorder (n = 44) and (B) controls (n = 22). Panel (C) shows statistically significant negative associations between scores on the autism spectrum quotient attention to detail subscale and k_i^cer values in autistic adults, overlaid on a single subject T1-weighted MRI scan, when family-wise error (FWE) rate-adjusted or unadjusted p-values of 0.05 are used (8 mm smoothing, threshold of k_i^cer ≥ 0.005).

Figure 1

Axial (left), coronal (middle), and sagittal (right) view of the mean cerebral [¹⁸F]-FDOPA uptake (k_i^cer min⁻¹; unadjusted and unsmoothed) in (A) adults with autism spectrum disorder (n = 44) and (B) controls (n = 22). Panel (C) shows statistically significant negative associations between scores on the autism spectrum quotient attention to detail subscale and k_i^cer values in autistic adults, overlaid on a single subject T1-weighted MRI scan, when family-wise error (FWE) rate-adjusted or unadjusted p-values of 0.05 are used (8 mm smoothing, threshold of k_i^cer ≥ 0.005).