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Bee Johnson
Opinion / Viewpoint

Autism may arise from brain’s response to early disturbances

by  /  18 August 2015
The Expert:
Expert

Mark Johnson

Professor, Birkbeck University of London

From the perspective of basic biology, the syndrome of autism presents some major puzzles. For example, we know that multiple genetic, molecular and neuronal pathways are associated with its development, and that these can differ from one individual to the next. Yet to a skilled clinician, the key behavioral symptoms of the syndrome are clear, raising the question of how different pathways can lead to the same general outcome.

Although autism involves atypical development, I don’t believe that we should refer to it as a ‘developmental disorder.’ In fact, it is a well-ordered developmental course that follows an unusual starting point. What are the implications of this view for current studies of autism?

Some researchers have aimed to find common elements in the molecular pathways regulated by the many different genes associated with autism1. I have an alternative interpretation: In my view, the key behavioral symptoms of autism result from a common adaptive response by the brain to any one of a range of different disturbances around the time of birth.

To draw an analogy from physical illness, an increase in body temperature is a common systemic response that helps us combat a variety of widely different alien attacks, both bacterial and viral. Although the factors triggering a fever can vary enormously in their biological or environmental origins, they elicit the same adaptive reaction, which can eventually alleviate the illness2.

Still, fever has negative side effects, and challenges to the immune system early in development can have lifelong consequences. Viewing autism in this light lets us address how an adaptive response by the brain to different genetic and molecular pathways gives rise to what is in fact a single syndrome.

Adaptive responses:

Much research in recent years has investigated how the human brain adapts to early genetic or environmental adversity, but these studies have mainly focused on brain mechanisms and cognitive strategies that help normalize behavior.

For example, some people with prosopagnosia, an inability to recognize individuals by their face, develop the ability to identify people by using other cues. As a result, the responses they present may seem typical to people who know them.

But adaptive processes during development do not always lead to a typical developmental trajectory. In a theoretical paper published earlier this year, my colleagues Teodora Gliga, Emily Jones and I proposed that self-regulatory operations help the brain adapt to subtle differences in the fidelity of processing at neuronal junctions called synapses3.

For example, in a process called ‘niche construction,’ an individual chooses to interact with the aspects of his environment that best fit how his particular brain processes information. Different kinds of disturbances to the efficiency of synapses can evoke the same responses from the brain as a whole, setting it on a developmental path that later results in the behavioral patterns characteristic of autism.

Another aspect of autism that needs to be explained is that both genetic and environmental factors can be important. For example, although autism is strongly associated with some disorders of known genetic cause, such as fragile X syndrome, high rates of autism traits are also common in children raised in impoverished early settings, such as Romanian orphanages.

We can address this issue by considering the ‘perceived environment’ — that is, the environment as processed by the brain — as the guide to adaptation. Even subtle brain differences early in life mean that different brains sample the same environment in different ways. In other words, the environment as experienced by the atypical brain is different, and it is this perceived environment that it adapts to over its developmental course.

In other cases, such as the Romanian orphanages, the brains of children may not differ significantly from typical, but the environment does, triggering the same whole brain adaptations.

Building on these points, I suggest that the main behavioral features of autism at the time of diagnosis reflect earlier processes of whole-brain adaptation, and so are not necessarily the direct products of an ongoing brain pathology.

For example, withdrawal from the social world may be a sensible adaptive response for a person whose brain early in life had trouble processing interactions with others. And once set upon this path of development, reversing it to restore typical behavior may be hard.

In the same way, an overly narrow focus of attention is a perfect adaptive strategy for a brain that has difficulty computing large quantities of information. By focusing on specific objects, or domains of interest, an atypical brain can tune in to a comprehensible subset of the world. Again, once set on this course, the brain later in life may not be flexible enough to widen its focus, even if the original underlying factors dissipate.

One area of research that I believe merits a new interpretation involves functional and structural brain imaging studies on adults diagnosed with autism. Typically, when researchers present results that show differences from neurotypical individuals, they interpret them as evidence of an underlying and continuing pathology.

I argue that these investigations essentially reveal the brain’s adaptations to differences that occurred earlier in development. It is sobering to reflect that such studies of brain structure and function in autism may not, in fact, inform us about the primary causes of the condition.

Another implication of our view is that researchers studying early interventions for autism will need to consider carefully whether an attempt to shift behavior or brain processes toward typical function (‘normalization’) is the most appropriate goal for an individual with autism.

One critical objective may be to identify whether the non-optimal synaptic function that triggered the adaptive process is still present at the time of intervention, or whether the original underlying problem was transient and has now resolved. If we can focus on determining the function of the adaptations at different stages of development, we will be better able to tailor interventions to individuals.

Mark Johnson is director of the Centre for Brain and Cognitive Development, Birkbeck College, University of London.

 

References:

  1. Krumm N. et al. Trends Neurosci. 37, 95-105 (2014) PubMed
  2. Kluger M. J. et al. Infect. Dis. Clin. North Am. 10, 1-20 (1996) PubMed
  3. Johnson M. H. et al. Dev. Psychopathol. 27, 425-442 (2015) PubMed

 


  • liz

    Brilliant! I would challenge you to consider that the adaptive response is ongoing and not just centered in the brain–immune, GI, sleep and other factors need consistent evaluation and consideration. But this sits better than most other theories with respect to both regression and individual variability–if truly genetic, why would ASD only occur in a portion of those with FRX or TS?

  • George Chris Michas

    environmental disturbances, like a less than optimal diet for each individual, for we are all individuals different from each other, and as such enjoy different optimal diets. Genetics and future understanding the genome will allow us to optimize personal diets

  • jorge

    These considerations certainly add a great deal of thought and wariness about ABA interventions attempting to “normalize” individuals, and which may end causing more harm than good. I have met individuals in spectrum that talk of PTSD symptoms caused by such behavioral approach when they were younger.

    • Julie Lachapelle

      My son did 9 months of ABA and it was the worst nine months of our lives. Worst decision we have ever made. ABA does not work for everyone. I have never thought of him as having PTSD but I totally see it now.

      • AutismDadd

        We did 7 years of ABA and achieved nothing. $$$ down the drain

  • Shonagh

    speaking as a parent, not a specialist, but as someone who spent years observing one particular developmental trajectory – with young adult outcomes that could not have been foreseen in early childhood – sensory overload and sensitivity were of more concern than the social impairments. That was what appeared to drive withdrawal behaviours. Over time, lack of experience of social interactions and the world at large form personality in certain ways. But I never saw profound social detachment or lack of mind reading skills. On the contrary.

  • Sue Gerrard

    I’d second what Shonagh says. Impairments in social interaction are what is most noticeable in people we describe as autistic, but it isn’t only the social world that autistic people withdraw from – anything involving sensory processing that’s experienced as uncomfortable is withdrawn from too. That can and does include food of certain colours and textures, water, clothing labels, noisy traffic and so on. The brain could certainly be adapting to the perceived environment, but the social nature of that environment, in my view, is a red herring that’s a legacy from the Freudian model of development embraced by early autism researchers.

    I’d also questions the clarity of the key behavioural symptoms to a skilled clinician. Between 1943 and 1956 Kanner completely revised the ‘essential common characteristics’ of his proposed syndrome and the key behavioural symptoms have morphed time and again since. Some skilled clinicians have had to revert to descriptors such as ‘bizarre’ and ‘odd’ to denote behaviour, suggesting that they were actually at a loss to put their finger on exactly what the behavioural symptoms actually were.

    For anyone who might be interested, I’ve blogged about the changes to the symptoms and syndrome of autism over the years in a series of posts from here onwards https://whatisautismanyway.wordpress.com/2012/04/04/a-critical-look-at-kanners-autism/

  • Shree C Vaidya

    Most of the time, what causes the behavioral symptom is environmental(Due to environmental).Therefore autism symptom comes under the behavioral spectra due to environmental factor, I think.Because DNA has copying and mimicking capacity.

  • Jeenu

    From observing severe autism for past 10 years and living with it daily:
    Social impairment is not the core deficit but a defense mechanism. The lack of eye contact is performed on purpose as to not
    activate certain part of brain which is very disruptive in autism. Also, the brain can not be miswired from birth. They are extremely intelligent with behavior changing on a daily basis. If one observe true autism stims, they are very different on a daily basis. But what drives this variability and uncontrolled stims, which could also explain tantrums and aggressivity.

    Unfortunately, many of researches are based on genes and not studying the individual profoundly to obtain real trends.
    The lack of sleep is so variable. The indvidual on autism can have neurotypical sleep patterns for days followed with severe disturbance for days. But why this variation? The questions are there, the kids are there but many researchers have chosen to study funded studies which prove to be fruitless one after another

  • ASD Dad

    It has been clearly evident that both the immune and neurological pathways in children with autism are interconnected, thus we begin to understand that immune insult and the environment encapsulated as mother (pregnancy) and child Pre and post natal) are the go to areas for understanding not only autism but a range of other mental health issues.

  • Lindsay

    That’s very Freudian of you. That theory,has been explored extensively. I feel autism needs understanding and awareness. ‘Autism Speaks’call for a cure while there is no ‘disease’ to be cured. Many people on the spectrum would not choose a nuerotypical life but instead would prefer to be understood and treated with dignity. The typical above-average IQ of an autistic person, may be the reason these pathways develop differently rather than it being the other way around.

  • (Eileen) Nicole Simon

    Autism’s many causes likely affect systems in the brain that have a special vulnerability. Vulnerable systems were revealed in experiments with monkeys on asphyxia at birth (WF Windle and RE Myers 1959-1972). S Kety (1962) and L Sokoloff (1981) found these vulnerable systems have higher blood flow and aerobic metabolism than anywhere else in the brain.

    Toxic injury is most prominent in the same sites affected by asphyxia. This was first reported by Wernicke in 1881 (translated by AD Thomson et al. 2008). The auditory pathway is most metabolically active, and should long ago been investigated as essential for language development. I tried (see N Simon, Echolalic Speech, 1975).

    I will continue to try to draw attention to the brainstem auditory pathway and basal ganglia as possible sites of injury in autism by all of its causes.

  • yankeegirl1

    Damaged.microglia.maybe? Dr. Mario Capecchi has done brilliant research on microglia.and mental illness. Well worth reading up on his work. http://www.ksl.com/?nid=148&sid=10947928

  • Katherin

    My granddaughter has autism, one of the things we have tried to do for her is to teach her how to interact with her family. We make her participate even when she reacts badly to situations. She is now 17 and can handle most social situations even though she is mostly nonverbal (she can say words but putting together whole sentences is difficult). We discovered early on that she could learn to sing songs so we teach her to say phrases like “My name is Mary” in a sing song voice. I belive constantly making her try new things and never giving up has helped her make progress over the years even though sometimes it is baby steps. I would like to encourage parents ans other family members to help expose these children to as many new things as possible, dont’n leave them at home with a baby sitter. It can be difficult, but including them is benificial to them, and can help you grow as a person.

  • AutismDadd

    Such complex thinking that can be summed up by saying if you alter a child’s genetic blueprint and or immune system, you will have atypical responses. Those who can’t fathom that the injection of vaccines results in an emergency response and altering of a child, ignores what weakness, fainting, seizures, anaphylactic response and death represent. An altered child will have many forms of atypical behavior and health outcomes.

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