Depression, Cancer, Inflammation, and Endogenous Opioids: Pathogenic Relationships and Therapeutic Options

Inflammation underlies a wide variety of physiological and pathological processes. Although the pathological aspects of many types of inflammation are well appreciated, their physiological functions are mostly unknown. The classic instigators of inflammation - infection and tissue injury - are at one end of a large range of adverse conditions that induce inflammation, and they trigger the recruitment of leukocytes and plasma proteins to the affected tissue site. Tissue stress or malfunction similarly induces an adaptive response, which is referred to here as para-inflammation. This response relies mainly on tissue-resident macrophages and is intermediate between the basal homeostatic state and a classic inflammatory response. Para-inflammation is probably responsible for the chronic inflammatory conditions that are associated with modern human diseases.

The hypothalamus-pituitary-adrenal (HPA) axis and its end product cortisol are essential for an adequate response to stress. Considering the role of stress as a risk factor for psychiatric disorders, it is not surprising that cortisol stress reactivity has frequently been investigated in patients versus healthy individuals. However, the large heterogeneity in measures of the cortisol stress response has hampered a systematic evaluation of the evidence. We here report of a systematic literature review and meta-analysis on cortisol reactivity to psychosocial stress across psychiatric disorders. Original data from authors were obtained to construct standardized cortisol outcomes (the areas under the curve with respect to increase (AUCi) and ground (AUCg)) and to examine the influence of sex and symptomatic state on cortisol stress reactivity. Fourteen studies on major depressive disorder (MDD) (n=1129), 9 on anxiety disorders (n=732, including social anxiety disorder (SAD), posttraumatic stress disorder, panic disorder and mixed samples of anxiety disorders) and 4 on schizophrenia (n=180) were included that used the Trier Social Stress Test or an equivalent psychosocial stress task. Sex-dependent changes in stress reactivity were apparent in MDD and anxiety disorders. Specifically, women with current MDD or an anxiety disorder exhibited a blunted cortisol stress response, whereas men with current MDD or SAD showed an increased cortisol response to psychosocial stress. In individuals with remitted MDD, altered cortisol stress reactivity was less pronounced in women and absent in men. For schizophrenia, cortisol stress reactivity was blunted in both men and women, but the number of studies was limited and showed evidence for publication bias. These findings illustrate that sharing individual data to disentangle the effects of sex, symptom levels and other factors is essential for further understanding of the alterations in cortisol stress reactivity across psychiatric disorders.

Background Depression is a common, disabling condition for which psychological treatments are recommended. Behavioural activation has attracted increased interest in recent years. It has been over 5 years since our meta-analyses summarised the evidence supporting and this systematic review updates those findings and examines moderators of treatment effect. Method Randomised trials of behavioural activation for depression versus controls or anti-depressant medication were identified using electronic database searches, previous reviews and reference lists. Data on symptom level and study level moderators were extracted and analysed using meta-analysis, sub-group analysis and meta-regression respectively. Results Twenty six randomised controlled trials including 1524 subjects were included in this meta-analysis. A random effects meta-analysis of symptom level post treatment showed behavioural activation to be superior to controls (SMD −0.74 CI −0.91 to −0.56, k = 25, N = 1088) and medication (SMD −0.42 CI −0.83 to-0.00, k = 4, N = 283). Study quality was low in the majority of studies and follow- up time periods short. There was no indication of publication bias and subgroup analysis showed limited association between moderators and effect size. Conclusions The results in this meta-analysis support and strengthen the evidence base indicating Behavioural Activation is an effective treatment for depression. Further high quality research with longer term follow-up is needed to strengthen the evidence base.