Associations between obesity and cognition in the pre-school years.

OBJECTIVE To test the hypothesis that obesity is associated with impaired cognitive outcomes in the pre-school years. METHODS Associations were examined between weight status at age 3-5 years and cognitive performance at age 5 years. Cognitive outcome measures were tests of pattern construction (visuospatial skills), naming vocabulary (expressive language skills), and picture similarity (reasoning skills). The sample was the UK Millennium Cohort Study (n = 12,349 participants). RESULTS Boys with obesity at 3 years had significantly lower performance in pattern construction at age 5 years compared to those of a healthy weight, even after controlling for confounders (β = -0.029, P = 0.03). Controlling for confounders, boys who developed obesity between the ages of 3 and 5 years had lower scores in pattern construction (β = -0.03, P = 0.03). "Growing out" of obesity had a positive association with picture similarity performance in girls (β = 0.03, P = 0.04). CONCLUSIONS Obesity in the pre-school years was associated with poorer outcomes for some cognitive measures in this study. Stronger relationships between obesity and cognition or educational attainment may emerge later in childhood.