Impaired mental rotation performance in overweight children

Abstract

Overweight children seem to have cognitive impairment. Since there is a relationship between motor and visual-spatial ability and because of the reduced motor abilities of overweight children we assumed that these children might show an impaired mental rotation performance. Sixteen overweight children (10 years of age) and 16 control children (10 years of age) were matched by age, gender, and socio-economic status. Each participant completed a general intelligence test, a motor test, and a chronometric mental rotation test. The results show differences in both motor ability and mental rotation accuracy. Overweight children made more errors when the rotation task was difficult compared to normal weight children. This study gives a clue to overweight children's problems in spatial cognitive tasks.

Introduction

Over the last few decades the prevalence of being overweight in childhood has increased considerably in almost all countries around the world (Wang & Lobestein, 2006). It is well investigated that being overweight as a child might lead to a number of diseases in adulthood, such as metabolic syndrome, hypertension, and cancer (Aggoun, 2007). Besides these medical problems, an association between cognitive impairment and being overweight is increasingly investigated (Li, Dai, Jackson, & Zhang, 2008). Possible reasons for this relationship are widely discussed. Some explanations are differences in the brain structure (Ho et al., 2010), a possible genetic predisposition, lower socio-economic status, or reduced physical activity (Bar-Or et al., 1998). Since cognitive functions include attention, perception, memory, language, problem solving, et cetera, the impaired cognitive function must be investigated in more detail. In a study with a nationally representative sample of more than 2500 children aged 8–16 years, an association between BMI and cognitive functioning was revealed. Z-scores from block-design test performance, a measurement of visual-spatial organization and general mental ability, was lower among children who were overweight or at risk of being overweight than those of children with normal weight (Li et al., 2008). This result holds true even when familial characteristics, sports participation, physical activity, hours spent watching TV, blood pressure, and lipid profile were adjusted. Cserjési, Molnár, Luminet, and Lénard (2007) showed that 12 overweight schoolboys at the age of 12 showed cognitive deficits in shifting and attention abilities compared to a control group of 12 boys with normal weight. Recently Verdejo-Garcia et al. (2010) showed selective alterations of particular components (inhibition, flexibility, and decision making) of executive functions in overweight adolescents compared to normal weight adolescents. Besides this, school age children that are overweight show a lower performance in many motor abilities than children that are not overweight (Okely, Booth, & Chey, 2004). There seems to be some relation between motor ability, being overweight, and spatial performance.

Motor development and movement experience are relevant factors for cognitive performance. This is especially true for spatial abilities (Campos et al., 2000), which are cognitive processes that involve visualization, orientation, and mental rotation (Linn & Petersen, 1985). Mental rotation is the ability to imagine how an object would look if rotated away from the orientation in which it is actually presented (Shepard & Metzler, 1971).

The relationship between motor ability and mental rotation performance has been investigated in correlation analyses (Jansen & Heil, 2010), quasi-experimental designs, experimental designs with interference and training studies. In a quasi-experimental approach it was shown that children with spina–bifida, a malformation of the central nervous system due to a defect of a neural tube closure in early embryogenesis, showed an impaired mental rotation ability compared to a healthy control group who was matched by age, sex and verbal-IQ (Wiedenbauer & Jansen-Osmann, 2007). Using an experimental interference paradigm Wexler, Kosslyn, and Berthoz (1998) found if a manual rotation task was compatible with a mental one, reaction times were faster and fewer errors were made. Besides this, the influence of motor training on mental rotation was shown in a training study, in which adults learned juggling for a period of three months. Their improvement in the post mental rotation test compared to the pre-test was much higher than that of the control group who did not receive juggling training (Jansen, Titze, & Heil, 2009).

The investigation of cognitive impairment in overweight children is limited by the fact that quasi-experimental designs were used, which are vulnerable to selection threats. Due to the experimental studies on the influence of motor training on mental rotation performance we assume that children that are overweight might have an impaired motor as well as impaired mental rotation performance. The investigation of cognitive impairment in overweight children is limited by the fact that quasi-experimental designs were used, which are vulnerable to selection threats. Because of this and the importance of family characteristics in the development of obesity, the socio-economic status of the families of the participants was controlled as well as their general intelligence.