Extreme Male Theory of Autism

Tuesday, June 30, 2009 at Tuesday, June 30, 2009
I have debated whether or not to approach the topic of Autism. After reading a recent article, I decided to broach it. I must preface this entry by saying that I do not study Autism, but it is definitely a very hot topic of study and research in the Neuroscience community. There have been quite a few theories presented as an explanation for why and how Autism is “caused”. As with any other disease or limitation of the brain, there are probably a host of reasons and causes for any one particular disease. This is very challenging for Neuroscientists, doctors, etc because it impacts our/their ability to find the most optimal rehabilitation or cure. On the other hand, the complexities of these various ailments of the brain just go to show how marvelous and intricate our brain is!

Autism is classified as a Pervasive Developmental Disorder. There are a variety of symptoms that typically appear before the age of 3. Symptoms are (but not limited to) impairments in social interactions, language development, repetitive behavior and limited interests. There is definitely a known genetic cause of Autism, however, whether or not it is caused by genetic mutations or a combination of “faulty” genes is unclear. There has been a recent surge in groups adamant that vaccines cause Autism. While I respect that these groups have some convincing evidence, overall this theory just doesn’t hold water when you look at the majority of scientific data from studies. Now before I go and piss off all of those who feel that vaccines have a strong correlation to Autism, I must remind everyone that correlation DOES NOT equal causation. Just because something is correlated, does not mean you can assume it has any real part in causing the ailment. However, I do feel that we probably over-vaccinate and the groups that try to link a correlation between vaccinations and Autism have definitely highlighted this point.

I just read an article that touched on a chemical exposure theory to Autism. This, in addition to a genetic predisposition, is probably a good summation of what contributes to the onset of Autism. The article was written by Harvey Karp, an Assistant Professor of Pediatrics at UCLA and (for all you Moms out there) the author of “The Happiest Baby”. The rational he presents in his article is pretty darn convincing. Here is the summation: our households are being invaded by a number of chemicals like formaldehyde, fire retardants, bisphenol A (BPA-an organic compound present in plastics), phthlates (substances added to plastics to increase durability, flexibility), etc. These little chemicals are known as known as endocrine disrupting chemicals (EDCs). “These substances are the focus of intense scrutiny because: 1) they're found in every home in America 2) they're increasingly linked to human disease 3) our exposure to them has risen in parallel with the surge in autism diagnoses and 4) they may theoretically affect the developing fetal brain” (Karp). In both humans and animal studies, EDC’s have been linked to a variety of health ailments including cancer, interruption of reproductive function and other hormone-related disorders. In 1996, Clinton and Congress designed tests and ordered the Environmental Protection Agency (EPA) to test various chemicals that were suspected to be EDC’s. However, when Bush came into office, testing was stopped and the law ignored. According to Dr. Harp, “our exposure to EDCs is no mere theoretical concern. In 2000, a Centers for Disease Control (CDC) study found detectable phthalates in 99.9% of adults including women of childbearing age. The CDC also discovered detectable levels of BPA in 93% of thousands of Americans tested (6 years of age and older)”.
A major concern is that these chemicals are found in women of childbearing age. Therefore, it is only logical to conclude that these chemicals could be passed from a pregnant woman to her fetus, and thus affect the developing brain. So now we introduce the “extreme male theory” of Autism. The theory is based on the premise that boys are approximately 4 times more likely to have Autism than girls. If something occurs, like exposure to one or an accumulation of many EDC’s, the effect may be over-masculinization of the brain. According to Karp, this theory is supported by 2 pieces of evidence: 1) elevated exposure to testosterone in utero results in a heightened male-type behavior (i.e. impaired language development) and 2) male and female autistic children show heightened male characteristics like impaired social and language development. EDC’s can cause masculinization in utero.
I am not suggesting that this “extreme male theory” is the end-all-be-all, but the evidence and research is pretty disconcerting. I do think we can go overboard and become too worrisome about trace level of chemicals. However, I personally work with formaldehyde and I can tell you that we take A LOT of precautions to limit our exposure as much as possible. It is a known carcinogen. So if adult exposure is harmful, surely exposure in utero, infancy or childhood is deleterious.

As a side note, concern over both BPA and phthalates has risen in both America and Europe and are being phased out of many products. In fact, I only buy BPA and phthalates-free products for my son.


Can't We All Just Bond?

Thursday, June 25, 2009 at Thursday, June 25, 2009
I have always been interested in how babies bond with their mothers. Multiple studies, including primates, have shown that early bonding occurs and is crucial for development. But just how important is this early interaction? How early is early? What are the benefits of early bonding?

Previous research has indicated some really cool immediate postnatal abilities. For example, immediately after birth, a baby has the ability to crawl up to Mommy’s breast and suckle! Which brings up an interesting side-note: why do some infants have a harder time learning how to breastfeed compared to others? But I digress. There are basically 2 camps in the research into early bonding. Camp 1 has shown research showing immediate benefits to the mother-infant contact. Babies that are intensively handled because of all of the neonatal tests, weighing, etc are negatively affected. Camp 2 did not find these negative effects, more specifically, did not show the beneficial effects of immediate mother-infant bonding. Research using multiple animal models has found deleterious effects if the separation from the mother is long-term. In newborn rats, long-term separation can result in an increased neuroendocrine response and basically make for a more stressed out adult rat. However, short-term experiences, via handling, actually shows an attenuated neuroendocrine response and a less stressed out adult rat. In primates, even a single long-term separation episode results social distortions in play and interactions.

I found an interesting article called “Neonatal Handling Affects Durably Bonding and Social Development” by Henry et al., 2009. The purpose of this study was to examine how intense handling and maternal separation 1 hour after birth affects the newborn. This study used horses. I know! Horses! But, as the article points out, horses and their babies (foals) are remarkably similar to humans. Horses have single births, show similar bonding after birth and have long suckling/lactating periods. The article also points out that foals exposed to human handling during the newborn period will go on to show a mistrust of humans. The basic design of the study was: Group 1: experimental foals who were separated from their mothers, handled for 1 hour immediately after birth; Group2: control foals were undisturbed after birth. Both groups were monitored from early development into adolescence in their natural environment. Here is what the study found: foals that had 1 hour of handling and were separated from their mothers immediately after birth had “insecure attachment to their mothers (strong dependency on their mothers, little exploration or play) and impaired traits of social competence (increased withdrawal and aggressiveness, impaired play) from an early age to young adulthood, while other behavioral features were not affected” (Henry et al. 2009). These results suggest that disruptions in the immediate interaction and bonding between a mother and her foal resulted in some pretty clear disturbances in the foals social functioning.

So I guess the obvious question is should we change the testing procedures for newborns? Is there more flexibility in human newborns to allow for some minimal separation?

Your thoughts or input?

Henry S, Richard-Yris M-A, Tordjman S, Hausberger M (2009) Neonatal Handling Affects Durably Bonding and Social Development. PLoS ONE 4(4): e5216.doi:10.1371/journal.pone.0005216

Music to my Ears

Tuesday, June 9, 2009 at Tuesday, June 09, 2009
I am sure every Mom has heard that exposing their infants/young children to classical music or learning to play an instrument make for a smarter, brighter child in general. But what effect does music really play on brain development and how does that translate (if at all) to other forms of learning? Before getting into the nitty gritty of the article, lets go over some key concepts. First and foremost is the wonderful way that our adult brains change in response to our environment and stimuli, called neuroplasticity. Until recently, scientists thought our brains did not have the potential to change, it was hard-wired. But some pretty landmark studies on monkeys and rats came out starting in the 1980’s and showed that, in fact, our brains DO change. Simply put: our environment, what we learn, new stimuli, all contribute to re-wiring and forming new connections in our brains, aka neuroplasticity. The brain of infants and toddlers is, in my opinion, even more remarkable. We are born with all of our neurons, yet, the synapses (part of the neuron that communicates with other neurons) are over produced. During the first formative years of life kids experience new things such as language, reading, etc. Their experiences help prune back these synapses. This is the main reason learning a variety of languages is easier at younger ages…kids have an over production of synapses just waiting for experiences, whereas adults have less and while our connections can be re-wired, it is a bit more challenging for us.

In March of this year an article came out in The Journal of Neuroscience about the effect of music on brain development in kids. The article is aptly titled “Musical Training Shapes Structural Brain Development”. The researchers looked at 2 groups of children: the “instrumental” group (15 kids) had weekly keyboard lessons for 15 months and a “control” group (16 kids) that only received 40 minutes of music class a week for 15 months. All kids were approximately 6 years old and were matched for gender, age and socioeconomic status. At the beginning and at the 15 month mark all kids underwent behavioral tests and MRI scans. The behavioral tests were meant to measure 1) fine motor skills of their fingers and 2) “music listening and discrimination skills” (Hyde et al., 2009). Their overall findings are that 15 months of music training led to regional specific structural changes in two important areas: motor and auditory areas. “Children who played and practiced a musical instrument showed greater improvements in motor ability (as measured by finger dexterity in both left and right hands) and in auditory melodic and rhythmic discrimination skills” (Hyde et al., 2009). However, improvements in visual-spatial or verbal domains were not seen. What this means is that learning a musical instrument did not transfer into improvements in brain areas not related to the learning of the instrument. The authors of this study state “these findings of structural plasticity in the young brain suggest that long-term intervention programs can facilitate neuroplasticity in children” (Hyde et al., 2009).

There were a couple questions that the either the authors mentioned or I thought of while reading the article. First, what if these “transfer” changes that were not seen would occur if the musical training would have been for a longer period? What if the instrument training included more sessions or longer sessions each week? Would you see similar changes in motor and auditory areas if the length of training was decreased but each training session was longer? What if multiple instruments were part of the learning?

I think that anecdotal and actual evidence exists to support the benefit of learning a musical instrument and how it can transfer to other forms of learning.

Any thoughts?

Hyde KL, Lerch J, Norton A, Forgeard M, Winner E, Evans AC, Schlaug G. Musical training shapes structural brain development. J Neurosci. 2009 Mar 11;29(10):3019-25

So I really can't use the TV as my babysitter...

Wednesday, June 3, 2009 at Wednesday, June 03, 2009
An article just came out in the Archives of Pediatrics & Adolescent Medicine which found an interesting correlation between the amount of television watched and a delay in language development. Here is the (over)simplified breakdown of the study. The study consisted of 329 infants/toddlers, ages 2-48 months. Once a month, using a recording device, the verbal interactions of the parent and child would be analyzed. What the researchers found is that for every hour the child watched television, there was a 7% decrease in the number of verbal interactions (words) between the caregiver and child. The researchers contend that this decrease may delay a child's language development. They cite that the American Academy of Pediatrics recommends against television watching before 2 years of age, and instead encourages more parent/child interaction.

I realize this is a hot-button issue. There are many DVDs out there claiming to improve language skills in babies. There is even a channel devoted entirely to babies! I would like to interject some caveats to this study. Overall the study is well done and here are some of the caveats or disclaimers they introduce. 1) Was the language captured by their recording device intended for the infant? In other words, was this a caregiver/child interaction, or was the caregiver talking to her sister on the phone? 2) The study does not know which television programs were watched by the infants. Furthermore, was the television show actively being watched by the infant, or was it merely background noise?

The study also points out what I kept asking myself while reading the article: what happens if the parent interacts with the infant about the content of the program while the child watches television. If you are watching The Wiggles or Barney would it delay language acquisition and/or development IF you were talking about what was going on in the show? The big answer...YES! I know, surprising. But the article points out that from the infants perspective, the overlapping sounds of the television and the caregivers voice would basically be sensory overload. The researches contend that it is difficult for an infant to attend to 2 sounds simultaneously (Christakis et al., 2009).

One study (Linebarger and Walker, 2005) found a positive relationship between children under 2 and watching television. The average onset for television watching was 9 months. This study found that certain television shows like Dora the Explorer, Arthur, etc were associated with positive language development. However, shows like Teletubbies and even Sesame Street were associated with negative language development.

However, as noted by Anderson and Pempek (2005) most research suggests that children under 2 gain very little, if anything from watching television.

So I guess here is what I keep wondering: how much interaction is optimal? I can't imagine some television viewing is bad, provided you are interacting with your child enough. Why would some shows be beneficial, and others not? And do these DVDs and show geared for children under the age of 2 structure their shows similar to the shows that research has found to be beneficial? Any other thoughts?

Works Cited:

Dimitri A. Christakis; Jill Gilkerson; Jeffrey A. Richards; Frederick J. Zimmerman; Michelle M. Garrison; Dongxin Xu; Sharmistha Gray; Umit Yapanel. Audible Television and Decreased Adult Words, Infant Vocalizations, and Conversational Turns: A Population-Based Study. Arch Pediatr Adolesc Med. 2009;163(6):554-558.

Linebarger, D. L., &Walker, D. (2005). Infants’ and toddlers’ television viewing and language outcomes. American Behavioral Scientist, 48, 624-645.

Daniel R. Anderson and Tiffany A. Pempek. Television and Very Young Children. American Behavioral Scientist, Vol. 48, No. 5, 505-522

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