Impaired Thinking in Patients with Breast Cancer and Depression

Abstract

Background: Brain-derived neurotrophic factor (BDNF) levels have been implicated in cognitive function and in the regulation of mood disorders, like depression. The aim of this study was to investigate the cognitive deficits of advanced cancer patients with depression and to assess the influence of various clinical factors on depression and cognition. Methods: Serum BDNF and plasma IL-6 were measured in patients treated for metastatic breast cancer diagnosed with depression according to DSM IV criteria. Cognitive function was assessed by the Piaget tasks and Verbal Learning and Memory Test, as a measure of short-term memory (STM) and long-term memory (LTM). Results: 29 patients with depression were compared to 27 matched controls without depression in this study. Even though both patient groups were of similar age, patients with clinical depression presented with a reduced Karnofsky performance status 66%. The presence of clinical depression was dependant on higher IL-6 levels (29.3 vs. 7.1 pg/ml; p=0.001) and cancer activity (p=0.002, χ2-test). BDNF had no direct association with depression. However, IL-6 level was an independent predictor of BDNF (b=-0.41, p=0.005). Patients with depression showed impairment of their ability to perform the Piaget tasks and a reduction in STM (4.0 vs. 6.8; p<0.001 and 18.9 vs. 32.3; p=0.003, respectively). Piaget tasks performance and STM were associated with lower BDNF levels (b=0.46, p=0.001 and b=0.23, p=0.043). Conclusions: Unlike IL-6, BDNF showed no association with depression in this population. Patients with low BDNF-levels and depression however, achieved lower scores in STM and Piaget tasks. The inability to perform the Piaget tasks adequately in this situation, demonstrates substantial difficulties in reasoning.