'I want bitty' says Harvey, the archetypal Peter Pan 'mummy's boy'.
Most people in the UK who have watched the comedy show Little Britain will know about Harvey and his constant desire for 'bitty'. For those who are perhaps unfamiliar with our quite eccentric humour here in the UK (we did of course bring the world the Ministry of Silly Walks), bitty in this case, is slang for breastfeeding or breast milk. Harvey is a character who despite being a grown-up, well-to-do man with a fiancee, still quite enjoys being breastfed by his mum, having never quite moved out of his infancy on this issue. The character is a parody for all those people out there - mostly men - who despite being quite capable, refuse to grow up and break from 'mummy's apron strings'. For the mums also who want to keep their precious at that age when the bond was so close.
Anyway. A while back I posted an 'other musings' entry on early infant feeding practices in light of the disparity of views of when to start weaning children from milk to food. One of the debates included as part of that story was the issue of breastfeeding. On purpose I did not get into the nitty-gritty debate of 'breast vs. bottle' being as I am the wrong gender to comment and respectful of the fact that such a decision is a matter of personal, informed choice or in some cases no choice. I am however interested in the various research into breastfeeding with regards to autism and lots of other childhood and developmental issues and areas.
Like many people have said before me, there is no doubt that breast milk has quite a lot going for it. If you need convincing, have a look at this document from the WHO detailing the beneficial effects of breastfeeding on areas such as health and intelligence (schooling). There is, as always, an important caveat attached to this document and the research in general, in that correlation does not necessarily imply causation and hence whilst an association might be strong statistically, there could be (and are) lots of other factors which influence such effects. Still breast milk, in its various stages and forms, carries quite a lot of nourishment and important compounds which can potentially help get a developing child off to a good start as well as being good for mum also. Suffice to say that before we got so good at making the modern infant formula feed, breast milk was the only (safe) way of nourishing a young infant for many, many generations of women.
The research base regarding breastfeeding and autism covers quite a bit of ground. Kanner, in his early descriptions talked about early feeding problems in his cohort but did not specify whether due to breast or formula. I don't really want to get too stuck on looking at any general association between breastfeeding rates and autism simply because (a) I think this is perhaps too simplistic an association to make (see correlation/causation argument above), and (b) there is always that risk of stigmatising mums who did or didn't breastfeed when all too often there are some complex processes in any decision made. The brief mention I will give to the analysis of breastfeeding rates in mothers with a child/children with autism suggests that there is no cut-and-dried answer of association. The study that my colleagues and I have published touching upon this area, suggested that breastfeeding rates were fairly high (60-69%) according to sub-diagnostic groups we looked at compared with the UK average of about 55% exclusive breastfeeding for the first 4 weeks of infancy. Other studies have shared such notions. Other parental surveys have reported slightly different results. Final answer: not cut-and-dried.
When it comes to any direct effects of breastfeeding in relation to autism, there are a couple of themes which emerge related to the composition of breast milk: a possible role of environmental pollutants and the structural composition of breast milk in relation to things like fatty acids and those pesky casomorphins which perhaps need addressing.
I am going to try and be quite careful when talking about contamination from environmental pollutants and breast milk. Careful because 'environmental pollutants' covers such a wide range of chemicals and compounds, some naturally occurring and some more man-made. Careful also because some of the studies indicating increasing environmental exposures found in breast milk have to be balanced against those indicating decreasing exposure in breast milk. Geography and other factors such as smoking seem to play their role, as does the influence of maternal diet. There is some small suggestion that higher levels of specific environmental contaminants passed through mothers milk are associated with specific outcomes for the child at later ages. Again with my balancing act in full.. er, balance, there is however quite a lot of evidence pointing in the other direction, suggesting that such contamination of milk are not associated with any specific negative outcomes, including results from some rather large studies here and here.
Where do the studies specifically with autism in mind stand on this issue? Well, they don't stand anywhere because aside from some discussion on what happens to rats who are given doses of selected pollutants equivalent to that derived from breast milk showing some neural disorganisation, there is very little direct evidence on pollutant composition of breast milk in relation to autism. Indeed, the recent CHARGE study on PBDEs in plasma of children with autism (not specifically looking at breast milk!) suggested that levels of this one class of pollutants showed no difference from controls, although all groups presented with high levels. Going back to that very complicated issue of parental age and autism, another study touched upon another possible contributing variable in that the longer we leave it to have children, the more scope there may be for parental (mother) accumulation of environmental pollutants to be potentially passed on through breast milk. Whether this could have an effect specifically on autism, I don't know.
The other issue about breast milk potentially linked to autism is its composition; with specific focus on fatty acids and casomorphins. There has been quite a bit of speculation about specific types of fatty acids in breast milk. This review provides quite a good overview of what types of fatty acids might be most important, their relative quantity in breast milk and associations with outcome. Readers of this blog might remember that fatty acids have cropped up quite a few times with regards to autism (and ADHD). There is some common sense in perhaps thinking that the fatty acids in breast milk might show some involvement with autism given the various studies indicating potential fatty acid deficiencies in some cases. I would perhaps temper this statement by saying that formula milk manufacturers have also caught on to this (and GOS and FOS), and generally include them in their formulations also.
The other side of this issue is in relation to breast milk and casomorphins. I know there has been a bit of a debate in relation to casomorphins (and gluteomorphins) with respect to autism and this is perhaps fodder for another post. What is widely accepted is that mammalian milk protein (casein) is eventually broken down to its constituent peptides and amino acids via hydrolysis. Mammalian milk covers human milk as well as milk from cows, goats, sheep, etc. Given the continued speculation on the involvement of casomorphins in some conditions including autism, there is perhaps some grounds for further research into any possible relationship. Is there any variability in the level of casomorphins according to the different stages of milk and is this consistent across all lactating mothers? This and other questions on things like lactose intolerance and breast milk might be interesting to examine in light of the recent Harvard findings on autism.
Given the length of this post and to save anymore people from switching off, I will stop there. I am not going to post any links to videos of Harvey and 'bitty' so as not to offend. Instead I offer a short excerpt from a movie that some of you may have seen which offers a new perspective on breastfeeding.