The resting regional cerebral blood flow (rCBF) patterns related to co-occurring symptoms such as inattention, hyperactivity, neurological soft signs and motor problems have not yet been disclosed in autism spectrum disorders (ASD). In this study thirteen adults with ASD and ten matched neurotypical controls underwent PET. The scores of rating scales for autistic traits, attention deficit hyperactivity disorder (ADHD) and neurological soft signs were included in a factorial analysis and correlated with rCBF. Factors corresponding to "autistic/ADHD traits," "sensory-motor integration" and "Intelligence/Motor sequencing" were identified. In the ASD group, positive correlations with CBF were found for "autistic/ADHD traits" in caudate bilaterally and the inferior parietal lobule, for "sensory-motor integration" in parieto-occipital cortex and for "Intelligence/Motor sequencing" in the right temporal cortex. Notably, CBF in the left thalamus correlated negatively with all three factors. Autistic traits and ADHD symptoms were associated with shared neural substrates. The correlation between "autistic/ADHD traits" and rCBF in the caudate is possibly associated with the executive impairments and ritualistic/stereotyped behaviors apparent in ASD. Furthermore, sensory-motor deficits were correlated with rCBF in the occipital visual cortex, involved in atypical visual perception in ASD. Various behavioral and neurological symptoms are suggested to converge into the ASD phenotype. (Contains 2 figures and 3 tables.)