Animal study indicates that neonatal exposure to the anesthetic sevoflurane may lead to abnormal social behaviors.

A review of: Maiko Satomoto, Yasushi Satoh, Katsuo Terui, Hideki Miyao, Kunio Takishima, Masataka Ito, Junko Imaki (2009). Neonatal Exposure to Sevoflurane Induces Abnormal Social Behaviors and Deficits in Fear Conditioning in Mice Anesthesiology, 110 (3), 628-637 DOI: 10.1097/ALN.0b013e3181974fa2

NOTE: THIS IS A PRE-CLINICAL (ANIMAL) STUDY. Read More

Two metabolites in the amygdala are associated with clinical impairment in autism.

A review of: Natalia M. Kleinhans, Todd Richards, Kurt E. Weaver, Olivia Liang, Geraldine Dawson, Elizabeth Aylward (2009). Brief Report: Biochemical Correlates of Clinical Impairment in High Functioning Autism and Asperger’s Disorder Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-009-0707-6
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A review of: Dubravka Hranilović, Zorana Bujas-Petković, Maja Tomičić, Tatjana Bordukalo-Nikšić, Sofia Blažević, Lipa Čičin-Šain (2009). Hyperserotonemia in autism: activity of 5HT-associated platelet proteins Journal of Neural Transmission DOI: 10.1007/s00702-009-0192-2 Read More

A review of: Christopher J. Keary, Nancy J. Minshew, Rahul Bansal, Dhruman Goradia, Serguei Fedorov, Matcheri S. Keshavan, Antonio Y. Hardan (2009). Corpus Callosum Volume and Neurocognition in Autism Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-009-0689-4 Read More

A review of: Molly Helt, Elizabeth Kelley, Marcel Kinsbourne, Juhi Pandey, Hilary Boorstein, Martha Herbert, Deborah Fein (2008). Can Children with Autism Recover? If So, How? Neuropsychology Review DOI: 10.1007/s11065-008-9075-9

In my last post I summarized a portion of a recent article examining the evidence for autism “recovery.” That first post was mostly focused on the definition of recovery, the evidence showing rates of recovery among children initially diagnosed with ASDs, and the factors that predicted increased rates of recovery. In this post I want to finish summarizing the original article by discussing the proposed mechanisms by which recovery may take place.

In sum, the authors state that recovery may occur as a function of one or several of the following mechanisms:

1. Normalizing input through attention
The general concept here is that some of the deficits in autism are due to limitations in attention or distraction that limits the child’s exposure to key stimuli (language, eyes, faces) that are critical for normal development. By redirecting the child’s attention to key stimuli via specific treatment interventions (e.g., ABA), it may be possible to help the child return to a more typical developmental trajectory.

2. Promoting the reinforcement value of social stimuli
This mechanism assumes that we are social because we are rewarded for being social. It is possible that children with autism lack the ability to experience internal rewards from social interactions, thus limiting the occurrence of such behaviors. By promoting such reinforcement (providing external rewards) we may be able to increase social behaviors by fostering the natural reinforcing properties of such behaviors

3. Early intervention provides enriched environments
Whether as the result of attention/distraction difficulties, or problems with the mechanisms that control the feelings of reward we experience during social interactions, one theory of autism suggests that limited environmental input contributes to the development of autistic symptoms. For example, children exposed to severe sensory deprivation (such as children in Eastern European orphanages), are at an increased risk for developing autism symptoms. Animal models have also shown that environmental deprivation leads to disruption in typical development, especially in the social realm. Therefore, early interventions may increase environmental sensory exposure (“enriched environmental opportunities”) facilitating a return to typical developmental trajectories among some children.

4. Early intervention provides mass practice and trials
This mechanism is based on the concept of neuro-cognitive rehabilitation. That is, that intensive repetition facilitates recovery of brain function, likely by facilitating the creation of new neural pathways. Therefore, this mechanism assumes that autism is at least partially due to problems during neural development that leads to an atypical neural organization. The mass repetition provided by intensive intervention would facilitate the development of new neural connections that normalize neural functioning, leading to a decrease in symptoms and neuro-cognitive deficits.

5. Compensatory processes
Similarly to #4, this mechanism suggests that even when brain organization can not be changed (as in irreversible brain damage), early intervention can lead to the development of compensatory behaviors or mechanisms that help the child “bypass” the original deficits. A simple example in physical rehabilitation is the case of right-handed person that suffers a stroke and loses functioning of his right hand. This person may, via intensive training, learn how to write well with his left hand, therefore compensating for the original deficit. In the case of autism, an example would be the case of implicit vs. explicit recognition of emotional facial expressions. Typically developing kids implicitly recognize facial expressions without necessarily needing to “break down” the components of such facial expression (e.g., shape of mouth, tears, etc). However, children with autism may have a deficit in this implicit system, but may learn to compensate for this deficit by developing explicit strategies (e.g., tears most often means sad) that would result in the same outcome: recognition of facial expressions.

6. Suppression of interfering behaviors
This is conceptually related to #1. Early interventions lead to suppression of behaviors that interfere with attentional focus to key environmental stimuli. For example, repetitive behaviors limit environmental input to usually one key non-social stimulus. Treatment interventions that reduce repetitive behaviors also result in an increase in behaviors that facilitate typical brain development, such as social interactions.

7. Limiting stress and arousal
Also conceptually related to #1 and #6, this mechanism indicates that early interventions reduces emotional arousal facilitating attentional focus to key environmental stimuli and also preventing the damaging effects of exposure to chronic stress.

8. Boosting recovery via biological treatments
Finally, biological interventions may facilitate recovery by enhancing the effects of the previously described mechanisms. For example, anti-anxiety medications may lead to a reduction of stress and arousal, thus facilitating the effectiveness of other behavioral interventions in promoting attentional focus, compensatory mechanisms, etc.

A final comment, please note that the mechanisms described above are simply the authors’ interpretation of what could be the underlying mechanisms for recovery. Although there is evidence to support these processes, these are entirely theoretical mechanisms, and the research on their validity is ongoing.