background The cognitive model of depression postulates that negative memory bias plays a central role in the aetiology and maintenance of depression.
aim Data from two studies will be presented with the aim to explain the concept of memory bias, its neural correlates and how it is related to genetic and behavioural measures.
methods Within the Brain Imaging Genetics (big) study, 448 healthy participants (aged 17-50 yrs; 63% female) donated saliva for genetic analyses and additionally, structural magnetic resonance imaging, on 1.5 T mri scanner, was carried out in 272 participants. Questionnaires on childhood life events scale and mood status were filled out through a web-based test battery. Memory bias was assessed using the self-referent encoding task.
First, the effects of mood status, childhood stress, brain derived neurotrophic factor (bdnf) Val66Met and 5-httlpr genotypes on memory bias were examined. And second, the association between memory bias and hippocampal and amygdala volume was investigated.
results Negative mood and adverse childhood events were associated with more negative memory bias and less positive memory bias. The effects of adverse childhood events were particularly apparent among males carrying the brain derived neurotrophic factor (bdnf) Met-allele and the 5-httlpr short-allele carriers.
Negative memory bias was also associated with larger amygdala and smaller hippocampal volume.
conclusion In non-depressed participants we found that the impact of adverse childhood events on affective memory bias is larger in bdnf Met-allele and 5-httlpr short-allele carriers. Furthermore, we showed that larger amygdala and smaller hippocampal volumes are associated with negative memory bias. This suggests that a larger amygdala impacts the smaller hippocampus and thereby biasing memory formation towards negatively valenced information. Taken together, these results imply that persons with negative memory bias may be more susceptible for depression and that negative memory bias can be seen as an intermediate phenotype for depression.