Oral Presentation Australian & New Zealand Obesity Society 2014 Annual Scientific Meeting

The relationship between overweight, obesity and cognitive function in adults: a systematic review and meta-analysis (#67)

Rebecca Cook 1 2 , Hoi Lun Cheng 1 3 , Nicholas O'Dwyer 1 4 , Jacqueline Raymond 5 , Kieron Rooney 1 2 , Katharine Steinbeck 3 , Helen O'Connor 1 2
  1. Discipline of Exercise and Sports Science, Faculty of Health Sciences, The University of Sydney, Sydney, NSW, Australia
  2. Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
  3. Academic Department of Adolescent Medicine, The Children’s Hospital at Westmead and Discipline of Paediatrics and Child Health, The University of Sydney, Sydney, NSW, Australia
  4. School of Human Movement Studies, Charles Sturt University, Bathurst, NSW, Australia
  5. Discipline of Exercise and Sports Science, Work Integrated Learning Unit, Faculty of Health Sciences, The University of Sydney, Sydney, NSW, Australia

Emerging evidence suggests that obesity may be detrimental to cognitive function.1,2,3 A systematic review and meta-analysis was undertaken to evaluate differences in cognitive performance between overweight/obese (BMI ≥25.0 kgm-2) and healthy-weight (BMI 18.5-24.9 kgm-2) adults. A systematic search conducted according to PRISMA guidelines across six databases netted 39,335 potential manuscripts with 17 included for review. The studies were relatively recent with all but one published in the last ten years. The overall sample (n=2,027) were predominantly middle-aged (mean age 39.5 years, range 18-92), with a relatively equal distribution of healthy-weight (n=1118) and overweight/obese (n=909) participants, although there was underrepresentation of males (26%). The array of psychometric tests administered (n=30) represented three cognitive domains: executive function, memory and information processing speed. Standardised Mean Differences (SMD, Hedges’ g) were combined and a pooled estimate of the effect of BMI category (healthy weight versus overweight/obese) on psychometric test scores was calculated using a random-effects model. Meta-analyses revealed small but significant effect sizes for executive function (SMD: -0.355; p<0.001) and memory (SMD: -0.265; p<0.05) and a non-significant effect for processing speed (SMD: -0.245; p>0.05). The results of the systematic review and meta-analysis support a negative association with cognitive function in overweight/obese adults, particularly in the executive function domain. Negative associations were found for memory and processing speed, although results were less consistent. Mechanisms underpinning lower cognitive performance in overweight/obese adults are unclear but co-morbidities including systemic inflammation and metabolic dysfunction may be contributing factors. The clinical implications of these findings and how these influence immediate and longer term daily cognitive function warrants further investigation.

  1. van den Berg E, Kloppenborg RP, Kessels RP, Kappelle LJ, Biessels GJ. Type 2 diabetes mellitus, hypertension, dyslipidemia and obesity: A systematic comparison of their impact on cognition. Biochim Biophys Acta. 2009; 1792: 470-81.
  2. Fitzpatrick S, Gilbert S, Serpell L. Systematic review: Are overweight and obese individuals impaired on behavioural tasks of executive functioning? Neuropsychol Rev. 2013; 23: 138-56.
  3. Smith E, Hay P, Campbell L, Trollor JN. A review of the association between obesity and cognitive function across the lifespan: implications for novel approaches to prevention and treatment. Obes Rev. 2011; 12: 740-55.