Influence of Body Mass Index on Visual Reaction Time: A Cross-sectional Analytical Study

Aims: To determine the relationship between Body Mass Index (BMI) and Visual Reaction Time (VRT) in medical students.

Study Design: Cross-sectional Analytical Study

Place and Duration of Study: Melaka Manipal Medical College, Melaka, Malaysia, between October 2014 and November 2014.

Methodology: We included 112 students (47 men, 65 women; age range 17-27 years) without medical conditions including neurological disorders, cardiovascular disorders and diabetes, which are known to affect cognitive function. Students were asked to complete a standard questionnaire before having their height measured using calibrated measuring tape in Frankfort plane, recorded to nearest 1cm and their weight measured using electronic weighing balance, recorded to nearest 0.1 kg. Body Mass Index (BMI) was calculated using Quatelet Index, and categorized using Asian BMI. Visual Reaction Time (VRT) was recorded using validated Human Benchmark program.

Results: Significant difference was seen in different groups in BMI, namely underweight, normal and overweight, with respect to visual reaction time. The other variables such as gender, ethnicity, caffeine consumption, fatigue level, exercise and handedness are not significantly associated with VRT.

Conclusion: Underweight individuals have been shown to have prolonged median visual reaction time as compared to their normal and overweight BMI counterparts. Further study on this is needed as BMI may not correlate well with the body fat composition of subjects, for which we propose further study to use waist-hip ratio instead.