Preliminary
evidence has pointed to reduced hippocampal
volume and abnormalities in cognitive function primarily in
the dorsolateral prefrontal cortex of patients with depression
and BD.30 Nolen-Hoeksema et al. suggested that
rumination could be a mediator between the BDNF gene
and depressive symptoms.4 Another study involving
200 female adolescents and their mothers found that
the Val/Val genotype of BDNF was associated with more
frequent rumination and childhood-onset depression
when compared with the Val/Met genotype; in mothers
with adult-onset depression, in turn, Val/Met was more
strongly associated with depressive symptoms.33 In both
the adolescents and their mothers, rumination was
a significant mediator of the relationship between the
Val/Val and Val/Met genotypes with regard to the
presence of depressive symptoms.