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Autism: Past, Present, Future, Speculative
Autism is all over the news right now, a very different situation than 18 years ago when we were looking for the cause of our son's developmental delay. Much of the media coverage, however, focusses on the sound-bite and tear-jerking opportunities that any problems with young children can provide. This is fine for the television crews, but it really does not inform the public, or help parents who are wondering whether their child could be autistic, or what to do with a child who is autistic.
Autism is a neurological condition, a developmental disorder. Increasingly, as the ability to image brain structure and trace brain function improves, it's evident that autism results from physical differences in the structure and function of the brain. Although it used to be considered a psychiatric disorder with an "emotional" cause, it is instead a physical problem, in the same way that a missing limb or eye is a physical problem. The autistic child's brain is not physically set up to process information the same way as an average baby's brain.
One of the most frustrating things for parents is that there is no single, obvious test for autism itself--there are only screening tests which look at children's behavior and skills, and compare them to those of average children the same age. These screening tests have improved (when our son was a toddler, we were told he could not be autistic because he clung to, and showed affection for, family members--not true) but they are not good enough, or widely known enough, to be trusted by non-specialist physicians and by school personnel. Tragically, many autistic children are refused services they need because a physician or a school counselor refuses to accept that the child is autistic. It is easier for a school, for instance, to label a child disruptive, difficult, oppositional, lazy, naughty, etc., than to admit that he is autistic and that they have been mistreating him for years.
In our society, issues of causation and blame arise whenever there's a problem. "Whose fault is it?" is often the first question parents ask a doctor when a child has a developmental problem. Years ago, when autism was believed to be a psychiatric illness, an emotional illness, doctors told mothers that they were the cause--it was the mother's style of parenting which made children autistic. They were wrong. While abusive parenting can produce some autistic traits in normal children, autistic children nearly always arrive with their problem.
Today, the loudest voices claim that immunizations cause autism. Their main argument is that children exhibit symptoms shortly after a series of shots. What they miss is that infants too young to have shots are also too young to look much different unless they have gross physical malformations or extremely low levels of behavior. An autistic infant and a non-autistic infant look the same at birth, and for some months after. But then the non-autistic infant develops on the average timetable, and the autistic infant--who has looked normal up until then--falls behind.
How can that be if something didn't "happen" right before the development slowed, ceased, or reversed? We are now learning things about the developmental process that show how a slowdown or halt could be pre-programmed to appear only later. Each stage in the complex development of a human's nervous system requires completion of a previous stage--just as you have to have the foundation complete before starting to put up the walls of a building. During the previous stage, both biochemical precursors and physical structures prepare the child to continue to and through the next stage of development. It's possible to have something go wrong--be missing, be chemically "underfunded" --at an early stage, which will not be needed until later. The problem shows up when there is a developmental "need" that can't be met. Imagine a builder working on a project who finds out, halfway through framing the second floor, that he can't get any more lumber, or someone putting together a puzzle who doesn't know there's a missing piece until the puzzle is well along toward completion.
It is clear from recent work on the structure and function of the human brain that autism results from specific problems in brain development which occur, in most cases, before birth, even though the results of those problems do not show up until the brain has reached the developmental stage where it needs the missing pieces. In many cases, there is evidence of subtle (and sometimes obvious) neurological difference in family members, especially when the extended family of both biological parents is considered. This strongly suggests that most autism is genetic in origin. It also suggests that improved therapy for autistic children, which helps them become more sociable and thus increases their chance of marriage and parenthood, will result in more autistic children being born to autistic parents.
What is it like to be an autistic individual? Only autistic individuals know for sure. Interviews with autistic people, their essays and books, all suggest that the autistic experience is just as varied as the non-autistic experience. Some people are happy. Some people are not happy. Some people have close friends. Some do not. The similarities imposed by the condition do not impose an emotional tone or even a core personality in the Myers/Briggs sense. Some autistic individuals, for instance, are extroverts; our son is one of them. From my reading, and from correspondence with autistic individuals online, I've come to think that autistic people are much more like the rest of us than previously thought. Their emotional lives are very much like mine: they want to be with people they enjoy being around, people who accept them for who they are, people who understand them, people who like them. They want to eat the food that tastes good to them, wear clothes that are comfortable for them, be in temperatures they find comfortable, do the things they think are fun. They want their concerns to be understood and taken seriously. They like people to get their jokes. They want to be respected.
One of the things which impressed me about our son, even before he could communicate in signs, gestures, or words, was the healthy quality of his emotional life. Yes, he screamed when he was upset, and I would have preferred a "Mom, I don't want to do that." But the things he enjoyed were reasonable, healthy things to enjoy: food that tasted good, music he liked, running around on the grass on a spring day. There was nothing weird about what he liked. His dislikes were harder to understand, but made sense once I realized that his sensory input was different than mine, and his responses were stronger. He felt hot when I barely felt warm. Tags in clothes (that I find only mildly irritating) bothered him a lot. He liked some colors more than others. Certain textures and flavors in food bothered him more. He liked some people and didn't warm up to others. These are perfectly normal responses in a small child--just on a different scale. His likes and dislikes tended to be more intense (typical of an earlier developmental stage: infants are usually very intense in their likes and dislikes.)
What is the "central deficit" in autism? This argument is still going on among researchers. My background in computer programming led me to what is not one of the main contenders at present, but the most recent brain imaging is beginning to lean my way. Although the human brain is not just a computer, some of the tools of information processing in computers can be useful in looking at how the brain handles information. In my opinion, the so-called central deficit is not central at all--in computer terms, it's not a problem with the main processor chip, but with something in the input/output stream: perhaps a buffer, perhaps an internal bus, perhaps a switching mechanism. Here's why I think this.
All autistic individuals I know about--and the parents of autistic children--agree that autistic people perceive the world a little differently than the average at the sensory level. That is, the primary raw sensory data is not getting to the central processor in the same way that it gets to the average brain. The odd patterns of extra sensitivity and insensitivity that autistic children display reflect this, as do the subtle (and sometimes obvious) differences in their patterns of attention and movement.
From computers, we know that "garbage in/garbage out" determines the computer's performance: the central processor will come up with wrong answers if the information going into it is wrong. If the input device, a keyboard for instance, is miswired or has a piece of potato chip under one key, then it may send the wrong signal to the processor when the user tries to send information in. If the input buffer--where information is stored temporarily before being sent on to the central processor--isn't big enough, information can be lost or transmitted out of order. If the internal communications channels are too slow, information backs up and may be lost, or the central processor may get ahead of itself and try to compute without having all the data. Some programs may require a pre-processor which performs computations on incoming data before it goes to the central processor; if the pre-processor doesn't work right, then the central processor is handed bad data to work with. These are just a few of the ways in which a computer can go wrong without having a problem in the central processor.
The human nervous system has analogues for all these and more. The peripheral nervous system--the nerves in fingers and skin and eyes and ears and tongue and nasal cavity--collects the sensory information which becomes the data input to the brain. When you have a cold, you lose the ability to smell most things--your brain then gets corrupted "smell data." When you have a sunburn, your skin tells your brain that a light touch is like a slap. When an arm or leg "goes to sleep" and becomes numb, your brain may think it's not even there. We have all experienced small, temporary glitches in our sensory input.
But there's another kind of problem that can arise, with the speed of transmission, not the accuracy of "pickup." Imagine a computer keyboard. You press A and A appears on the screen; it has also reached the central processor, so that if A is a command (A for add, A for another, A for Aunt Alice's email address) the computer responds to that command. The speed of transmission of that electrical signal makes it possible to send commands, or type a message, as fast as you can type. Now imagine that the keyboard has a very slow connection. You type A, and nothing happens. The seconds tick by. Finally an A pops up on the screen. It would take a long time to compose a message to Aunt Alice--or to give a series of commands for an accounting program--if you had such a slow connection. Or suppose the keyboard would not transmit an A at all unless you pressed on the A key for five seconds. That would also slow down the transmission of information, even if the actual transmission time were the same.
The human nervous system can have similar glitches. Research has shown that some people have "slower" nerves than others--it takes longer for an electrical impulse to travel from the finger to the brain than it does for others. And it's also shown that some people need sensory impulses to last longer before they're captured (slow capture rate.) This can have serious consequences. For instance, in normal speech, the sounds of many consonants are very brief--on the order of 75 milliseconds. If an infant cannot capture such brief sounds--needs the sound to last, say, 200 or 300 milliseconds before it's "caught"--then the infant will not even "hear" the sounds of most consonants. If the infant doesn't hear them, then they don't become part of the library of speech sounds which the infant uses to build a model of speech, and understand which sounds are speech and which aren't. Some non-autistic children with severe language delay have exactly this problem. Some autistic adults who can now talk have described what speech sounded like to them when they were small--and they say it was like 'mooing' or 'groaning'--full of vowel sounds, not consonants.
A problem with slow capture rate that affects more than one sensory channel would interfere in a number of ways with information processing and normal development. Autistic individuals have problems with interpreting the rapid changes in facial expression which modify verbal communication--recognizing the brief twitch of an eyebrow or quirk of the lips that changes "You stinker" from an angry insult to a loving compliment, for instance. They often have difficulty interpreting similarly rapid changes in pitch, rate, prosody that interact with the words spoken. They may be unable to "see the picture" on a TV screen, because of the rapidly scanning raster. They may not feel a brief painful stimulus, or may feel a painful stimulus delayed from its actual onset. If the slow capture rate and a slow transmission rate are combined, it's clear that the data available for processing on the inside would always be out of phase with what's going on outside. Many parents report that autistic children are slow to respond even when they can respond appropriately: here is one physical model that might explain why they're like that.
Sensory integration--the ability to combine sound, sight, touch, and other senses into one coherent sensory experience--is another area in which most autistic persons have problems. Some autistic adults describe being unable to understand speech unless they deliberately shut off the visual channel (shut their eyes, look down.) In the average infant, sensory integration develops over the first few years in a seamless way. But if the capture rate and/or transmission rate of the senses are not synchronous--if the visual channel and the sound channel are out of synch, as you sometimes see on TV--the infant has no way to make them match. As an adult, you know how to adjust if the announcer's mouth and speech aren't in synch. But an infant has no prior experience to work from. If your mouth is making the motion for one sound while the infant hears another, then looking at you will not help him copy that sound.
There's another complication which few computers possess. Most computers will sit passively waiting for information to come to them. The silicon chip doesn't care if it's computing or not. The human brain, however, is not capable of sitting idle in the dark, so to speak; it will make things up and amuse itself while waiting for data to arrive. If the data from normal sensory channels doesn't arrive, something else will be going on--and when the sound or the sight or the touch signal does arrive, the brain will work it into the pattern it had already created. Our brains are pattern-makers. The rigid patterns of play typical of autistic kids--stacking blocks over and over, laying out objects in repetitive sequences--are quite possibly the result of the brain's pattern-making ability going to work on whatever is available. You see similar behavior in average kids and adults when they're bored--they swing their legs, tap pencils, doodle rows of similar designs.
Adding to that complication is another. The human brain is not only busy all the time, in childhood it is also always growing....and it grows in response to its experience, both in terms of structure (the neurons and their connections) and function (what it can do, what calculations it can make.) If its experience is limited, possibly because the data coming in are limited in comparison to the data that average children can acquire, then its growth will also be limited and aimed in the direction of the activity it can perform. What this means is that the brains of adult autistic individuals are not necessarily representative of the brains (and potentials) of autistic infants and young children. It is not a good idea to reason backward from the structure of an adult autistic's brain to assume that the same structures are missing in the infant's brain. It's important to remember that the final structure and function of anyone's brain reflects both innate structure and developmental experience, just as the outward physical condition of a 60 year old reflects both inherited physical characteristics and how that body was used throughout life. The 60 year old ballet dancer will have a different body than a twin who never danced.
Why am I so sure that the central aspects of cognition are not the problem in autism? Observation, both of autistic children and (through their writing) of adult autistic individuals, combined with a knowledge of how information processing works in complex systems like computers and humans. Where autistic individuals are presented with correct data in a sensory format they can use (such as math), they reason clearly and well; they understand cause and effect in physical (nonsocial) situations very well. Many if not most autistic children have no trouble learning letters, numbers, and they may pick up reading (simple decoding) even faster than the average child. But letters and numbers hold still on the page. Where they clearly fall behind is in situations where the necessary data require sensory processing in multiple channels--which all social interaction definitely does.
Neurocognitive research on brain function is already helping to define the way that typical brains work--how we convert our sensory input into a model of the world, how we use that model to communicate with each other and manipulate things around us. The next stage for research into autism will be to define how the brains of autistic people work. It will be important to go beyond defining "different" to discovering what the difference is, and what its implications are for development. Interventions to help autistic children should be based on their reality--on the way their brains actually do function, rather than on guesses. Once we know--at the biochemical, molecular level--how typical brains grow, develop, and function...and we know how the brain of an autistic child grows, develops, and functions...precisely targeted intervention will become possible.
Contents of these pages ©1996-2016 Elizabeth Moon
This essay ©2003 Elizabeth Moon