Serum and plasma levels of brain-derived neurotrophic factor in individuals with eating disorders (EDs): a systematic review and meta-analysis

Abstract

Background Brain-derived neurotrophic factor (BDNF) is essential for neuronal survival, differentiation, development, and plasticity. Evidence suggests that fluctuations in peripheral levels (i.e., plasma or serum) of BDNF are associated with eating behaviors. Nevertheless, the findings are inconsistent. The purpose of this study is to determine if serum or plasma levels of BDNF are altered in individuals with eating disorders (EDs) compared to controls. Methods We conducted a systematic search of the core electronic medical databases from inception to March 2022 and identified observational studies that compared individuals with EDs to controls without EDs on serum or plasma levels of BDNF. R version 4.0.4 was used for all visualizations and calculations. Results The current meta-analysis comprised 15 studies that fulfilled the inclusion criteria. Subjects with EDs (n = 795) showed lower BDNF levels compared to non-EDs controls (n = 552) (SMD: − 0.49, 95% CI [− 0.89; − 0.08], p-value = 0.01). Moreover, subgroup analysis was conducted based on the specimen (plasma and serum), which revealed no statistically significant difference in the levels of BDNF between the two subgroups (p-value = 0.92). Additionally, meta-regression results revealed that publication year, mean age of the individuals with EDs, NOS scores, and the number of individuals with EDs collectively accounted for 25.99% percent of the existing heterogeneity. Conclusion Lower BDNF levels are associated with EDs.

Barking up the wrong biomarker? Correspondence to Shobeiri et al. (2022) “Serum and plasma levels of brain-derived neurotrophic factor in individuals with eating disorders (EDs): a systematic review and meta-analysis”

“…However, although the study of Shobeiri et al [ 1 ] has many strengths including state of the art meta-analytic methods and solid statistical analysis (e.g., leave-one-out analysis), we have some critical concerns regarding the study selection process, and consequently, the results obtained and the conclusions that can be drawn from them. Shobeiri et al [ 1 ] state that studies were only included if they (a) were observational, measuring BDNF levels in individuals with EDs without other psychiatric or neurological comorbidities and (b) provided sufficient data, i.e., number of participants, mean, and standard deviation (SD) of BDNF levels.…”

“…However, although the study of Shobeiri et al [ 1 ] has many strengths including state of the art meta-analytic methods and solid statistical analysis (e.g., leave-one-out analysis), we have some critical concerns regarding the study selection process, and consequently, the results obtained and the conclusions that can be drawn from them. Shobeiri et al [ 1 ] state that studies were only included if they (a) were observational, measuring BDNF levels in individuals with EDs without other psychiatric or neurological comorbidities and (b) provided sufficient data, i.e., number of participants, mean, and standard deviation (SD) of BDNF levels. However, using the search criteria applied by Shobeiri et al [ 1 ], we identified six studies that either met inclusion criteria [ 2 , 3 ], would have met them if the authors had requested data from the investigators [ 4 , 5 ], or simply calculated SDs from the reported statistical measures (i.e., 95% confidence intervals, interquartile ranges) [ 6 , 7 ].…”

“…Shobeiri et al [ 1 ] state that studies were only included if they (a) were observational, measuring BDNF levels in individuals with EDs without other psychiatric or neurological comorbidities and (b) provided sufficient data, i.e., number of participants, mean, and standard deviation (SD) of BDNF levels. However, using the search criteria applied by Shobeiri et al [ 1 ], we identified six studies that either met inclusion criteria [ 2 , 3 ], would have met them if the authors had requested data from the investigators [ 4 , 5 ], or simply calculated SDs from the reported statistical measures (i.e., 95% confidence intervals, interquartile ranges) [ 6 , 7 ]. In fact, all of these studies were included in a recent meta-analysis of BDNF in AN that had similar inclusion criteria [ 8 ].…”

“…We read with great interest Shobeiri and colleagues’ [ 1 ] recent review and meta-analysis of 14 studies on peripheral concentrations of brain-derived neurotrophic factor (BDNF) in females with anorexia nervosa (AN) and bulimia nervosa (BN) [ 1 ]. Across the studies included in the meta-analysis, Shobeiri et al [ 1 ] found peripheral levels of BDNF to be lower in individuals with eating disorders (EDs) in comparison to healthy controls (HC).…”

“…We read with great interest Shobeiri and colleagues’ [ 1 ] recent review and meta-analysis of 14 studies on peripheral concentrations of brain-derived neurotrophic factor (BDNF) in females with anorexia nervosa (AN) and bulimia nervosa (BN) [ 1 ]. Across the studies included in the meta-analysis, Shobeiri et al [ 1 ] found peripheral levels of BDNF to be lower in individuals with eating disorders (EDs) in comparison to healthy controls (HC). These meta-analytic results indicating the potential involvement of BDNF in the pathogenesis of EDs (indicative of a trait marker) and/or as an indicator of clinical response to therapy (indicative of a state marker) are important and will likely motivate and guide both research and clinical practice for years to come.…”