symptoms that are almost always observed. This chart shows that although the symptoms listed are different, it is easy to get confused between many of them. There is a co-occurrence between ADHD and APD. A systematic review published in 2018 detailed one study that showed 10% of children with APD have confirmed or suspected ADHD. It also stated that it is sometimes difficult to distinguish the two, since characteristics and symptoms between APD and ADHD tend to overlap. The systematic review mentioned here described this overlap between APD and other behavioral disorders and whether or not it was easy to distinguish those children that solely had auditory processing disorder. Relation to specific language impairment and developmental dyslexia There has been considerable debate over the relationship between APD and Specific language impairment (SLI). SLI is diagnosed when a child has difficulties with understanding or producing spoken language for no obvious cause. The problems cannot be explained in terms of peripheral hearing loss. The child is typically late in starting to talk, and may have problems in producing speech sounds clearly, and in producing or understanding complex sentences. Some theoretical accounts of SLI regard it as the result of auditory processing problems. However, this view of SLI is not universally accepted, and others regard the main difficulties in SLI as stemming from problems with higher-level aspects of language processing. Where a child has both auditory and language problems, it can be difficult to sort out the causality at play. Similarly with developmental dyslexia, researchers continue to explore the hypothesis that reading problems emerge as a downstream consequence of difficulties in rapid auditory processing. Again, cause and effect can be hard to unravel. This is one reason why some experts have recommended using non-verbal auditory tests to diagnose APD. Specifically regarding neurological factors, dyslexia has been linked to polymicrogyria which causes cell migrational problems. Children that have polymicrogyri almost always present with deficits on APD testing. It has also been suggested that APD may be related to cluttering, a fluency disorder marked by word and phrase repetitions. It has been found that a higher than expected proportion of individuals diagnosed with SLI and dyslexia on the basis of language and reading tests also perform poorly on tests in which auditory processing skills are tested. APD can be assessed using tests that involve identifying, repeating or discriminating speech, and a child may do poorly