Happiness in Medicine

Again and again, quality of life (QOL) in different forms is shown to correlate to better recovery from cancer (and other health issues). I find these papers depressing - we'll never get health insurance to pay for trips to Disneyworld, better food, or social programs for people with cancer. A recent paper in the Journal of Clinical Oncology shows a correlation of this type, but claims no causation:

Title: Decrease in Depression Symptoms Is Associated With Longer Survival in Patients With Metastatic Breast Cancer: A Secondary Analysis

Authors: Janine Giese-Davis, Kate Collie, Kate M.S. Rancourt, Eric Neri, Helena C. Kraemer, and David Spiegel

Purpose Numerous studies have examined the comorbidity of depression with cancer, and some have indicated that depression may be associated with cancer progression or survival. However, few studies have assessed whether changes in depression symptoms are associated with survival.

Methods In a secondary analysis of a randomized trial of supportive-expressive group therapy, 125 women with metastatic breast cancer (MBC) completed a depression symptom measure (Center for Epidemiologic Studies–Depression Scale [CES-D]) at baseline and were randomly assigned to a treatment group or to a control group that received educational materials. At baseline and three follow-up points, 101 of 125 women completed a depression symptom measure. We used these data in a Cox proportional hazards analysis to examine whether decreasing depression symptoms over the first year of the study (the length of the intervention) would be associated with longer survival.

Results Median survival time was 53.6 months for women with decreasing CES-D scores over 1 year and 25.1 months for women with increasing CES-D scores. There was a significant effect of change in CES-D over the first year on survival out to 14 years (P = .007) but no significant interaction between treatment condition and CES-D change on survival. Neither demographic nor medical variables explained this association.

Conclusion Decreasing depression symptoms over the first year were associated with longer subsequent survival for women with MBC in this sample. Further research is necessary to confirm this hypothesis in other samples, and causation cannot be assumed based on this analysis.

While this paper shows correlation, it does not show causation. IE, perhaps the group with increasing depression had increasing depression because the cancer was progressing more rapidly. It is difficult to tease out the causation, but a paper that we read for a group meeting a few months ago did so. It used mice housed in different environments and was able to actually determine which pathway was affecting the cancer.

Title:Environmental and genetic activation of a brain-adipocyte BDNF/leptin axis causes cancer remission and inhibition.
Authors:Cao L, Liu X, Lin EJ, Wang C, Choi EY, Riban V, Lin B, During MJ.

Cancer is influenced by its microenvironment, yet broader, environmental effects also play a role but remain poorly defined. We report here that mice living in an enriched housing environment show reduced tumor growth and increased remission. We found this effect in melanoma and colon cancer models, and that it was not caused by physical activity alone. Serum from animals held in an enriched environment (EE) inhibited cancer proliferation in vitro and was markedly lower in leptin. Hypothalamic brain-derived neurotrophic factor (BDNF) was selectively upregulated by EE, and its genetic overexpression reduced tumor burden, whereas BDNF knockdown blocked the effect of EE. Mechanistically, we show that hypothalamic BDNF downregulated leptin production in adipocytes via sympathoneural beta-adrenergic signaling. These results suggest that genetic or environmental activation of this BDNF/leptin axis may have therapeutic significance for cancer.

Of course, the New York times might not make a big differentiation between these two papers, but scientifically it is huge. It is difficult to do this type of study in humans - to clearly show causation - because an important step to genetically engineer mice to be lacking the pathway that has the effect. So the best we can manage (for now) is to show correlation. And as long as it is "only" correlation, I think happiness-based healthcare (or at least, paid for by insurance) won't happen.