Of course, any effort to pigeonhole a diagnosis is at the mercy of the repertoire of the available “official” pidgeonholes sanctioned by the exisiting diagnostic manuals. In the minds of many people inhabiting the world of neurodevelopmental disorders,these pigeonholes are blissfully few: dyslexia, autism or “the spectrum”, Asperger’s syndrome, pervasive developmental disorder, and of course ADHD. In the minds of some such people their diagnostic world is further blissfully simplified: it is a set of one, ADHD being that one. Aside from the general hazards ofconjuring upsuch an unrealistically simplified clinical world, one particular consequence thereoff is particularly jarring. This relates to memory impairment as the cause of learning difficulties. Needless to say, sound memory is paramount for the success of any learning process,and memory impairment is likely toput the learning process at agreat disadvantage.But because a pigeonhole for “memory-based learning disabilties” has not been created in available diagnostic manuals, memory impairment as the primary cause of neurodevelopmental difficulties is typically overlooked and the the cases of primary memory impairment are artificially and erroneously forced into some of the “official” diagnostic categories where they don’t belong. But if one considers some ofthe most common causes of neurodevelopmental disorders, it becomes clear that memory impairment should be expected. What are these causes? Perinatal hypoxia is certainly among them and we know that the hippocampi – the brain structures particularly important in memory – are also particularly oxygen-demanding; so any hypoxia-producing event is likely to impact the hippocampi and thus affect memory. In utero or perinatal viral encephalopathies are another category of causes responsible for neurodevelopmental cognitive difficulties. They, too, are particularly likely to impact the limbic structures critical for memory. Then there are seizures, and we know that the mesial temporal-lobe regions – right whre the hippocampi and related structures are found – are particularly epileptogenic. So there are many reasons to look for memory impairment in an academically underachieving child or adolescent, despite the fact that the diagnostic manual designers failed to create a diagnostic pigeonhole for it.
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