Related Experiment Video
Updated: May 13, 2026

The Unpredictable Chronic Mild Stress Protocol for Inducing Anhedonia in Mice
Published on: October 24, 2018
Association between the BDNF Val66Met Polymorphism and Chronicity of Depression
Yujin Lee1, Shinn Won Lim, Soo Yeon Kim
1Department of Psychiatry, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Objective:
Both clinical and biological factors influence the course of depressive disorders. This study tested for associations between the brain-derived neurotrophic factor (BDNF) gene at the Val66Met locus and the course of major depressive disorder (MDD).
Methods:
Three hundred ten Korean subjects (209 patients, 101 controls) were genotyped for rs6265 at nucleotide 196 (G/A), which produces an amino acid substitution at codon 66 (Val66Met) of the gene for BDNF. Course of illness was evaluated both by chronicity of current episode (episode duration >24 months) and by the lifetime history of recurrences.
Results:
Patients with the Met/Met BDNF genotype had a significantly higher rate of chronic depression than all others. There was a significant dose effect of the Met allele on chronicity. Compared with the Val/Val genotype, the relative risk of chronicity was 1.67 for the Val/Met genotype, and 2.58 for the Met/Met genotype. Lifetime history of recurrent episodes was not related to BDNF genotypes but was significantly associated with younger age of onset and with a history of depression in first degree relatives.
Conclusion:
BDNF genotyping may be informative for anticipating chronicity in major depression.
Related Concept Videos
Long-term Depression
Calcium Ion Concentration Mechanism
If over time, all...
Long-term Depression
Human Genetics
The complex relationship between genetics and psychology is observable through common biological components such...
Depression: Overview
Depressive Disorders: Etiology
Biological Factors in Depression
Biological predispositions significantly influence the risk of developing depressive disorders. Genetic studies highlight the role of variations in the serotonin transporter...
Depressive Disorders: MDD and Dysthymia
