The Impact of Breastfeeding to Cognitive Functions in 5 Years Old Children

The Impact of Breastfeeding to Cognitive Functions in 5 Years Old Children. The impact of breastfeeding to cognitive development was studied in two cohorts of children aged five years, born in the years 2013 and 2014 in the polluted district Karvina and the control district České Budejovice. Information about breastfeeding was obtained from mothers´ questionnaires. The Bender Visual Motor Gestalt Test (BG test) and the Raven Colored Progressive Matrices (RCPM test) were used as psychological cognitive tests. Obtained results suggest a positive effect of breastfeeding lasting 6 months and/or longer on cognitive development in 5 years old children. This effect was more pronounced in the BG test results focusing on visual-motor skills compared to the RCPM test results measuring problem-solving skills.


Introduction
Recently, we studied the impact of air pollution on cognitive development in 5 years old children during their prenatal period.
The study was located to the Moravian-Silesian Region as it is considered the most polluted region in the Czech Republic by PM2.5 (particulate matter < 2.5 mm) and polycyclic aromatic hydrocarbons (PAHs) as B[a]P (benzo[a]pyrene] and control region Southern Bohemia. Two districts were selected: the more exposed between the cognitive achievements and breast feeding. Therefore, we also analyzed a possible relationship between the length of breastfeeding and cognitive development in the two cohorts of children mentioned, differing by a distinct level of air pollution: Karvina.PM2.5 mg/m3 37.7±14.7, B[a]P ng/m3 6.1±4.53, Ceske Budejovice PM2.5 mg/m 3 17.1±4.8, B[a]P ng/ m3 1.19±1.28 [3].

Measures of Child Visual-Motor Functioning and Intellect
To be able to examine the potential effect of breastfeeding on cognitive development in 5 years old children, two psychological assessment instruments were used, namely the Bender Visual Motor Gestalt test (the BG test) and the Raven Colored Progressive Matrices test (the RCPM test). From a variety of possible standardized tools, these two methods have been chosen considering the age of the tested children and the fact that measurement should have been successfully done in one session. Both methods are usually well received by children and help them adapt to the test situation. 5 years old children from our cohort were tested individually. The child psychologist who administered the psychological assessment instrument was unaware either of the fact whether the given child had been breastfed or how long did the breastfeeding took if relevant. In order to assess level of visual-motor functioning in 5 years old children, the Bender Visual Motor Gestalt test (BG test) was used. The test focuses on assessing motor functioning, visual perception, and potential developmental or neurological impairments in children and adults [8].
146 children at the age of 5 years completed the test. Each of our 5 years old children was presented with nine cards depicting different geometric shapes. The cards were presented individually and the tested children were asked to copy the design, trying to make the best reproduction possible. Test results were scored based on the organization and accuracy of the reproduction. This drawing test was well received by children and helped them considerably to get used to and feel comfortable with the test situation. Once the BG test was completed, the children were presented with a non-verbal intelligence test called Raven Colored Progressive Matrices (RCPM test) [9] that was also used in a similar study in Krakow, Poland [6]. The test has been developed and widely used for assessing reasoning and problem-solving ability in children between 5 and 11 years, including those suffering some kind of physical or mental impairment. The RCPM test consists of three sets of twelve matrix designs with increasing level of difficulty. 145 children at the age of 5 years completed the RCPM test.

Questionnaire for Mothers
Mothers engaged in the study provided us with information regarding social environment of the family, breastfeeding and eating habits, and child´s medical history. Similarly, the data regarding gestational age, birth weight, birth length, head circumference, and Apgar score were collected in order to be taken into account while analyzing psychological test results. Breast feeding details from maternal questionnaire has been in form of 3 particular questions: if the mother breastfed, how long she breastfed the baby fully and for how long the mother breastfed the child at least partially.

Statistical Analysis
The length of breastfeeding has been standardized into months and split into two groups, breast feeding up to 6 months and more than 6 months. Both groups have been compared with each other using Mann Whitney U-test in total and in particular groups by regions and children gender. Other potential values from the questionnaire have been tested as potential confounders -see in Table 1.

Results
The tested confounders are shown in Table 1 (p < 0.001), boys (p < 0.01) as well as girls (p < 0.05). Obtained results indicate generally more significant effect of full breastfeeding lasting 6 months and longer. It may be also speculated that the full breastfeeding may have more significant effect on future cognitive development in children living in district of Karvina which is more exposed to air-pollution Table 3. illustrates impact of maternal education levels on result of cognitive testing. Children of university graduated mothers have significantly higher level of RCPM score in all groups. For BG test score is this impact significant only for boys, but there is significantly lover score levels for mother's lover secondary in all. Note: Results of Mann Whitney U-test compare by region *) p ~ 0.05, **) p ~ 0.01, ***) p ~ 0.001 and by gender +) p ~ 0.05, ++) p ~ 0.01, +++) p ~ 0.001. Note: Results of Mann Whitney U-test compared by Breastfeeding length *) p ~ 0.05, **) p ~ 0.01, ***) p ~ 0.001  [15] advocated that nutrients in breast milk may improve general child cognition compared to infants fed formula only. Kim and Choi [16] studied associations between the breastfeeding and cognitive function in children up to 8 years. Children breastfed > 3 months scored significantly higher on communication and problem solving.
Similarly, Lenehan, et al. [17] demonstrated in children breastfed > 2 months increased IQ and nonverbal IQ at 5 years of age.
Study by Lopez, et al. [18] identified a strong association between breastfeeding duration and general Ability scores in children aged 9 / 10 years, with the greatest effect found in those breastfed for more than 12 months. Longitudinal cohort study in Australia [19] examined the relationship between duration of breastfeeding and motor development outcomes at 10, 14, and 17 years. Breastfeeding for more than 6 months was positively associated with improved motor development outcomes. Our results suggest a positive effect of breastfeeding lasting 6 months and/or longer on cognitive development in 5 years old children.
This effect was more pronounced in the BG test results focusing on visual-motor skills compared to the RCPM test results measuring problem-solving skills.