METHODS: A multistage sampling was performed across rural primary schools in Kuala Krai, Kelantan, Malaysia. Data were collected using self-administered questionnaires and the children aged 10-11 years (n=312) were subjected to cognitive tests including digit span, letter-number sequencing, coding, and symbol search. Cognitive performance was tested using subscales derived from the Wechsler Intelligence Scale for Children.
RESULTS: The prevalence of SHS exposure at home was 55.8%, where 11.9% of children lived with one smoker, while 43.9% of children lived with ≥2 smokers. There was a significant difference in the mean score of the combined cognitive tests between SHS-exposed and non-exposed children after adjustment for sex, parental educational level, family income and academic performance [Pillai's Trace=0.084, F statistic (df)=6.803 (4302), p<0.001].
CONCLUSIONS: More than half of the primary school children in rural Kuala Krai were exposed to SHS from at least one smoker at home. There was a significant association between SHS exposure at home and cognitive performance.
SUBJECTS/METHODS: Urine color was used to measure hydration status, while fluid intake was assessed using the 15-item beverage intake questionnaire. Cognitive function was assessed using the Wechsler Intelligence Scale for Children, Fourth Edition.
RESULTS: More than half of the adolescents were mildly or moderately dehydrated (59.6%) and only one-third (33.0%) were well hydrated. Among the daily fluid types, intakes of soft drinks (r = -0.180; P = 0.006), sweetened tea (r = -0.184; P = 0.005) and total sugar-sweetened beverages (SSBs) (r = -0.199; P = 0.002) were negatively correlated with cognitive function. In terms of hydration status, cognitive function score was significantly higher (F-ratio = 4.102; P = 0.018) among hydrated adolescents (100.38 ± 12.01) than in dehydrated (92.00 ± 13.63) counterparts. Hierarchical multiple linear regression analysis, after adjusting for socio-demographic factors, showed that soft drinks (β = -0.009; P < 0.05) and sweetened tea (β = -0.019; P < 0.05) negatively predicted cognitive function (ΔR2 = 0.044). When further control for sources of fluid, hydration status (β = -2.839; P < 0.05) was shown to negatively predict cognitive function (ΔR2 = 0.021). The above variables contributed 20.1% of the variance in cognitive function.
CONCLUSIONS: The results highlight the links between fluid intake (soft drinks, sweetened tea, total SSBs) and hydration status with cognitive function in adolescents. Interventions aimed at decreasing the consumption of SSBs and increasing hydration status through healthy fluid choices, such as water, could improve cognitive performance in adolescents.