The Auditory Working Memory of 13-15-Year-Old Adolescents Using Water with Varying Fluoride Concentrations from Selected Public Primary Schools in North Kajiado Sub County.

Abstract

Water contributes significantly to the physiological functions in the in the human body. However, low fluoride doses have been reported to affect the central nervous system (CNS) without first causing the physical malformations of dental and skeletal fluorosis. Aims and objectives were to determine fluoride concentrations in water used by adolescents who were born and raised in North Kajiado and correlated it with their Auditory Working Memory Index (AWMI). The survey was cross-sectional and descriptive involving 269 school children aged 13-15 years. A purposeful sampling frame was used to select the schools. Fluoride in water was determined using the Fluoride Ion selective electrode. The AWM was assessed using the Wechsler intelligence scale for Children V (WISC-V) subtest. The mean auditory working index for the group was 111.5±22.6 while the boys had a mean AWMI of 111.46±22.37 and the girls 111.56±22.75. A comparison of the AWM of children from low (105.40±23.6) and high (99.52±23.2) fluoride schools and medium with high fluoride school had significant differences. The AWM for the children whose household water had low fluoride had higher AWMI 122.58±19.9 compared to those whose household had high fluoride in the with ANOVA F (2, 266) = 17.968, p<.0001 and Tukey HSD for low and medium (m=-5.919, se=3.146, p=.145, low and high fluoride, (m=-18.559. se=3.124, p<.001; medium and high (m=-12.640, se= 3.32, p<.001 at 95% CL. In conclusion, low fluoride in the water seemed to enhance the AWM. However, the AWM declined with an increased in the fluoride concentration in water.

EXCERPT

Distribution of auditory working memory according to water fluoride in school areas: Levels of AWM and the school water fluoride: There were 116 (43.1%) gifted individuals attending the seven selected schools out of 269 while 45 (16.7%) were above average, 59 (21.9%) were average, 16 (6%) were below average, and 33 (7.4%) were mentally challenged.Low water fluoride in the school and environs: In the schools whose water fluoride was between 0.5-1 mg/l there were 68(25.3%) out of the 269 children who attended the school and 34(35.3%) were gifted, seventeen (25%) were above average, 10 (14.7%) were average, while two (5.9%) were below average and five (23.5%) were mentally challenged, Figure 12.

High water fluoride in the school and environs: There were four schools whose water fluoride content, was above 1.6 mg /litre, and the total number of students attending the four schools was 168 (62.5%) out of 269. The children who were gifted in the high fluoride area were 58 (34.5%) out of the 168. Twenty four (14.3%) were above average, forty-five (26.8%) were average while 14 (8.3%) were below average and 27(16.1%) were mentally challenged, Figure 12.

A comparison of the AWM of the children attending schools in the low fluoride area and that of those attending medium fluoride areas with Mann-Whitney U, 867.500, Z =-2.062 and p=0.39. Also, there significant differences in the auditory working memory of 68 (25.3%) children whose household water contained low fluoride concentrations (0-0.8mg/litre) when compared to the auditory working memory of 168 (62.5%) children whose household water contained fluoride concentrations of ? 1.6 mg/litre, a Mann-Whitney U=4261.5, Z-3.184 and p?.001 at 95% CL. Similarly, a comparison of the auditory working memory between 33(16.4%) whose schools water supplies and the environs had medium fluoride and168 (83.6%) individuals whose water had high fluoride ?6 mg/litre and significant differences were observed with a Mann-Whitney U=1548.5, Z=-4.194, p?.001 at 95% CL.

The ANOVA analysis indicated significant differences in the auditory working memory within the children in the low, medium and high fluoride in school and environs water supply. Similarly, significant differences were observed between the children in the low, medium and high fluoride in the school and environs water supplies with F (1, 267) = 14.848, p?.001 at 95% CL. A positive linear relationship was noted with a regression analysis where r=230, p?.001 at 95% CL. The value for R²= 0.059, an indication that fluoride concentration in the school and the environs water supplies contributed 5.3% towards auditory working memory with beta=.230, t= 3.853, p?.001 at 95% CL.

Low, medium, and high fluoride in household water and the Levels of Auditory working memory: The Auditory working memory of the children were categorised according to the fluoride concentration in the water samples brought from their household as low medium, and high. There were 116 (%) who were gifted, 45 (%) were above average, 59 (%) were average, 16 (%) were below average, and 33 (%) were mentally challenged Figure 13…

The current study found a higher proportion of children with high AWM in low household water fluoride than in high water fluoride areas. The finding in the current study is contrary to what a study in India reported higher fluoride levels resulted in higher levels of intelligence [17]. Memory is defined merely as the ability to retain information over time. Auditory memory is the ability to take orally presented information, process it, store it and be able to recall what was heard [18]. This cognitive functioning requires one to be attentive, record, process, store and retrieve the information when needed. Poor AWM results when children can’t record, process, store or retrieve the information that was exposed to, this has negative consequences on learning. Children with low AWL find it challenging to pay attention and follow instructions. AWM plays a critical role in literacy as it has a direct impact on reading and writing, spelling and mathematics skills. According to Cyndi Ringoean, a neuro-developmentalist, a child with poor AWM cannot learn using the phonics method [19]. When even doing self-reading, listening and processing the information when the child needs to do silent reading a good AWM to recall what was read. Addie Cusimano also opines that AWM is overlooked as a learning skill deficiency and he found severe deficiencies in children with hyperactivity and or attention deficit disorders [19]. Working memory is strongly correlated to intelligence in adults and children hence those performing better on working memory tasks have also shown a tendency to be better on the intelligence task [20] [21]. Several animal studies have tried to explain the possible mechanisms of neurotoxicity of fluoride [22] [23]. Fluoride when ingested through the child’s diet or crosses the placenta, its retained in the body about 80-90% in children and 60% in adults [15] [24]. Its absorbed into the bloodstream and forms complexes which are lipid soluble and can cross the blood-brain- barrier hence accumulating in the cerebral tissues [16]. This complexes then affect the development of the CNS by different mechanisms, e.g. inhibition of glutamate transporters, free radical generation and inhibition of mitochondrial energy and antioxidant enzymes [25]. This alteration in the structure and function in the CNS especially during the 1^st eight years of life and also during foetal growth may lead to cognitive dysfunction, intellectual deficits and learning difficulties [22] [25]. Fluoride has also been shown to interfere with thyroid gland activity leading to an adverse effect on the development of the brain and function in children [26].

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FULL-TEXT STUDY ONLINE AT http://article.sapub.org/10.5923.j.ajmms.20180810.04.html
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