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Several studies suggest that breast-fed babies become more intelligent children than formula-fed babies (e.g., Lucas et al 1992).

Questions

  • To what extent overall does research support the association between breastfeeding and intelligence increases?
  • Is it reasonable to conclude that the association is causal?
  • Or alternatively, are there better alternative explanations for the association?

References

  • Lucas, A., Morley, R., Cole, TJ, Lister, G. & Leeson-Payne, C. (1992). Breast milk and subsequent intelligence quotient in children born preterm. The Lancet, 339, 261-264.
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Welcome to the site. It's an interesting question. I'm just curious, but (a) is this an assignment? Also, (b) are you interested in the general question of whether breast feeding is linked to intelligence gains or are you more concerned with a critical reading of Lucas et al 1992? –  Jeromy Anglim Sep 3 '12 at 0:09
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I don't understand what kind of answer you expect. Do you expect us to read the paper for you and summarize it? Do you want us to do a forward Scholar search? This seems to be a well known paper and, as @JeromyAnglim suggested, it looks like you want us to do your homework for you. I have voted to close as NARQ until you refine this to a specific question that shows that you have carefully read the paper (past the abstract) in question. –  Artem Kaznatcheev Sep 3 '12 at 23:14
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@ArtemKaznatcheev I really like the question in general. So I've edited the questions to focus on the general question of the causal link between breastfeeding and intelligence increases, and removed what appeared to be the "assignment-like" qualities of the previous question that focused on reviewing a single study. –  Jeromy Anglim Sep 3 '12 at 23:52

1 Answer 1

Kramer et al 2008 is an excellent study of this question because it utilizes intervention, thus lending strength to the claim of causation, concluding that IQ was "significantly higher in the experimental group for both reading and writing".

But is it the milk itself? Some argue that it's also the skin-to-skin contact, and the mother-child bonding. Academic success has been shown to be strongly correlated with emotional intelligence (e.g., Parker et al, 2004 found $r=.33$ between GPA and EI in a large sample of high school students) and some Attachment Theory proponents claim closer parental relationships lead to stronger emotional intelligence. However, some studies demonstrate that only adults happiness is positively effected by percieved parental attachment, not emotional intelligence (e.g., Sillick & Schutte, 2006) and that emotional intelligence is correlated with a dismissive attachment style (Kafetsios, 2004).

The Arch Gen Psych article comments on potential mechanisms:

Even though the treatment difference appears causal, it remains unclear whether the observed cognitive benefits of breastfeeding are due to some constituent of breast milk or are related to the physical and social interactions inherent in breastfeeding. Concentrations of essential long-chain polyunsaturated fatty acids are higher in human milk than in infant formula. Randomized trials of supplementation of infant formula with long-chain polyunsaturated fatty acids, however, have yielded inconsistent results in both term [21] and preterm [22] infants. Another potentially important component of breast milk that could be responsible for the observed cognitive differences is insulinlike growth factor I, which is contained in higher concentration in breast milk than in formula [23] and has been shown to be absorbed intact across the newborn infant's gastrointestinal tract.[24]

On the other hand, studies showing long-term epigenetic behavioral effects of licking and grooming by mother rats of their pups [25] suggest that the physical and/or emotional act of breastfeeding might also lead to permanent physiologic changes that accelerate neurocognitive development. Finally, it is possible that the increased frequency and duration of maternal-infant contact implicit in breastfeeding vs bottle-feeding could increase verbal interaction between mother and infant, which might also have a stimulatory effect on cognitive development.

[21] Simmer K. Longchain polyunsaturated fatty acid supplementation in infants born at term [update of: Cochrane Database Syst Rev. 2000;(2):CD000376]. Cochrane Database Syst Rev 2001; (4) CD000376

[22] Simmer K, Patole S. Longchain polyunsaturated fatty acid supplementation in preterm infants [update of: Cochrane Database Syst Rev. 2000;(2):CD000375]. Cochrane Database Syst Rev 2004; (1) CD000375.

[23] Nagashima K, Itoh K, Kuroume T. Levels of insulin-like growth factor I in full- and preterm human milk in comparison to levels in cow's milk and in milk formulas. Biol Neonate 1990;58 (6) 343- 346

[24] Philipps AF, Rao R, Anderson GG, McCracken DM, Lake M, Koldovsky O. Fate of insulin-like growth factors I and II administered orogastrically to suckling rats. Pediatr Res 1995;37 (5) 586- 592

[25] Weaver IC, Cervoni N, Champagnhttp://ojs.lib.swin.edu.au/index.php/ejap/article/viewFile/71/100..e FA, D'Alessio AC, Sharma S, Seckl JR, Dymov S, Szyf M, Meaney MJ. Epigenetic programming by maternal behavior. Nat Neurosci 2004;7 (8) 847- 854

References

  • Kafetsios, K. (2004). Attachment and emotional intelligence abilities across the life course. Personality and Individual Differences, 37, 129-145.
  • Kramer, M.S., Aboud, F., Mironova, E., Vanilovich, I., Platt, R.W., Matush, L., Igumnov, S., Fombonne, E., Bogdanovich, N., Ducruet, T. & others (2008). Breastfeeding and child cognitive development: new evidence from a large randomized trial. Archives of General Psychiatry, 65, 578.
  • Parker, J.D.A., Creque, R.E., Barnhart, D.L., Harris, J.I., Majeski, S.A., Wood, L.M., Bond, B.J. & Hogan, M.J. (2004). Academic achievement in high school: does emotional intelligence matter?. Personality and Individual Differences, 37, 1321-1330. PDF
  • Sillick, T.J. & Schutte, N.S. (2006). Emotional intelligence and self-esteem mediate between perceived early parental love and adult happiness. E-Journal of Applied Psychology, 2. PDF
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Jeromy, I don't mind edits at all. The way I see it, answers belong to the public domain. But I see a typo in the last inline reference ([25] Weaver IC). Not sure what you were going for there as far as formatting. –  Keegan Keplinger Sep 21 '12 at 20:33

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