A meta-analysis of circulating BDNF concentrations in anorexia nervosa

Objectives. Brain derived neurotrophic factor (BDNF) is involved in neuroplasticity, and in the homeostatic regulation of food intake and energy expenditure. It also has a role in stress responsivity and reward processing. On the basis of its involvement in these various processes, BDNF can be hypothesized to be an important factor in the development and maintenance of anorexia nervosa (AN). This study meta-analytically summarizes investigations of serum BDNF concentrations in people currently ill with AN, in comparison to healthy controls. Methods. Seven studies measuring BDNF in serum of individuals with AN (n = 155) and healthy controls (n = 174) were identified and included in the meta-analysis of the mean differences between case and control groups. Results. This study confirms that AN is associated with decreased serum BDNF concentrations, in comparison to healthy controls. The combined effect size (standardized mean difference, SMD) was large (SMD =-0.96; 95% CI 1.33 to-0.59; P < 0.001). Significant heterogeneity of effect sizes was identified (I ² = 58.3%; P < 0.001), which emerged as being primarily attributable to the first published study on the investigated association. Conclusions. The present meta-analytical summary of studies measuring circulating BDNF concentrations in women with AN and healthy controls confirms that it is significantly reduced in this patient group. Difficulties associated with the measurement of BDNF have been identified and potential confounding factors have been discussed. Current data do not allow inferences to be made about causal links between levels of circulating BDNF and AN. However, possible explanations for the relationship between BDNF and AN have been presented.