You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: EEG-Based Processing and Classification Methodologies for Autism Spectrum Disorder: A Review 
Chapter Title:  Behaviour-Independent Diagnostic Practice 
1. Abstract of Cited Paper (BIB001):  Abstract Children with ADHD and autism have some similar features, complicating a differential diagnosis. The purpose of our study was to determine the degree to which core ADHD and autistic symptoms overlap in and discriminate between children 2–16 years of age with autism and ADHD. Our study demonstrated that 847 children with autism were easily distinguished from 158 children with ADHD. All children with autism had 15 or more of the 30 Checklist for Autism Spectrum Disorder symptoms (mean 22), and none of the children with ADHD did (mean 4). Three of the symptoms were present only in children with autism. Almost all 30 symptoms were found in over half of the children with autism, whereas none were present in the majority of children with ADHD-Inattentive type (ADHD-I) or in children with ADHD-Combined type (ADHD-C) without comorbid oppositional-defiant disorder. In contrast, ADHD symptoms were common in autism. Children with low and high functioning autism and ADHD-C did not differ on maternal ratings of attention deficit, impulsivity, and hyperactivity. For children with normal intelligence, nonsignificant differences were found between children with autism, ADHD-C, and ADHD-I on neuropsychological tests including measures of attention, working memory, processing speed, and graphomotor skills.

Literature Review:
According to a recent CDC report, one in 59 children in the United States has been diagnosed with ASD (Baio et al., 2018) . In 2010, it was calculated to be 1 in 68. Thus, it is evident that the prevalence of ASD is increasing over the years. ASD might not be a fatal disease, yet the daily activities of autistic people are extremely challenging. Even though ASD cannot be cured, the symptoms can be improved through proper individualized treatment. An early diagnosis would facilitate starting the medication, therapies and social skills training at an early age which enhances a child's response to treatment. A significant challenge is that the current clinical diagnosis practices are subjective, especially behaviour dependent. Current diagnostic procedures require input from a team of multi-disciplinary professionals. Besides, a complete profile of the child's abilities is required for an accurate diagnosis. Such comprehensive evaluations sometimes take several months or even years, delaying the diagnosis and the treatment. Also, current nosological systems and ASD severity measures work well for children above the age of three, however not so accurate for children younger than two years of age. Early diagnosis of ASD is difficult as the defining behaviours often become significant only after the first three years and routine well-baby check-ups do not contain simple, reliable measures to identify them. Early diagnosis of milder forms of ASD is even harder as the symptoms tend to overlap with several other diagnoses. Moreover, the early diagnosis needs to be re-evaluated because of rapid development in early ages and the impact of the intervention  . There also exists the problem of misdiagnosis BIB001 . The symptoms for ASD being diverse and several symptoms being overlapped with other diagnoses similar to ADHD BIB002 are the major causes for the misdiagnosis. The fact that etiology and developmental course are getting more diverse with time makes future diagnosis even more challenging. By developing behaviourindependent diagnostic approaches which are simple, affordable and easy to implement in the routine wellbaby check-ups, these challenges can be resolved.