Hippocampal Mechanisms Linking Chronic Pain and Depression

Development of depression-like behavior and altered hippocampal neurogenesis in a mouse model of chronic neuropathic pain

Chronic-pain patients often suffer from depression. In rodent models of neuropathic pain, animals develop depression-like and anxiety behaviors, indicating a relationship between chronic pain and affective disorders. However, the underlying neurobiological mechanisms linking chronic pain and depression are not yet fully understood. Neurogenesis in the hippocampus is a fundamental process related to brain plasticity. Reduced neurogenesis has been associated with the development of mood disorders and cognitive impairments. The current study aims to elucidate the underlying long-term changes in brain plasticity induced by neuropathic pain in mice at a time point when depression-like behavior has already developed. Furthermore, our focus is set on alterations in neurogenesis in the hippocampus. We found that manifestation of anxiety- and depressive-like behavior as well as cognitive impairment co-occur with decreased survival of newly generated cells but not with impaired proliferative activity or reduced number of immature neurons in the dentate gyrus area of the hippocampus. Moreover, we detected an impairment of differentiation of newly generated cells into mature calbindin-positive neurons, accompanied with a shift towards increased differentiation into astroglial cells. These findings indicate that a reduction in mature functional neurons, rather than reduced proliferation or neuronal progenitor cells, are the long-term changes in hippocampal plasticity that manifest in neuropathic pain conditions after depression-like behavior has developed.

Indirect costs in patients with coronary artery disease and mental disorders: a systematic review and meta-analysis

OBJECTIVES

The aim of the present study was to systematically review the association of comorbid mental disorders with indirect health care costs in patients with coronary artery disease (CAD).

MATERIALS AND METHODS

A comprehensive database search was conducted for studies investigating persons with CAD and comorbid mental disorders (Medline, EMBASE, PsycINFO, Psyndex, EconLit, IBSS). All studies were included, which allowed for a comparison of indirect health care costs between CAD patients with comorbid mental disorders and CAD patients without mental disorders.

RESULTS

The literature search revealed 4962 potentially relevant studies, out of which 13 primary studies met the inclusion criteria. Depression was investigated most often (N = 10), followed by anxiety disorders (N = 3) and any mental disorder not further specified (N = 3). All studies focused on return to work as indirect cost outcome. CAD patients with depression showed diminished odds for return to work, compared to CAD patients without depression (OR = 0.37; 95% CI: 0.27-0.51). The findings for comorbid anxiety and any mental disorder were inconsistent. Indirect health care costs were exclusively assessed by a patient self-report (N = 13).

CONCLUSIONS

There is strong evidence for diminished odds of return to work in CAD patients with comorbid depression, highlighting the need for integrated CAD and depression care. With regard to other comorbid mental disorders, however, the evidence is sparse and inconclusive.