Here are five studies on the loose theme of how the mind affects the body, and the body affects the mind ... and that the distinction between mind and body is pretty arbitrary anyway.  Using meta-analysis, Chida & colleagues highlight considerable evidence suggesting that stress-related psychosocial factors have an adverse effect on cancer incidence and survival.  Andersen & colleagues report a randomized controlled trial to respond to this in women diagnosed with breast cancer.  Women in the stress management arm of the study received an initial one-year, 26 session intervention in groups of 8 to 12 people.  The aim was to reduce distress and improve quality of life, improve health behaviors (diet, exercise, smoking cessation), and facilitate cancer treatment compliance and medical follow-up. Strategies included the following: progressive muscle relaxation for stress reduction, problem solving for common difficulties (eg, fatigue), identifying supportive family members or friends capable of providing assistance, using assertive communication to get one's psychologic and medical needs met, strategies to increase daily activity (eg, walking, exercise), improving dietary habits (eg, lowering fat intake), and finding ways to cope with treatment side effects (eg, nausea) and maintain adherence to medical treatment and follow-up.  At 11 year follow-up, the death rate in the women who underwent the stress management intervention was less than half that of women who underwent treatment as usual.

Another meta-analysis by Chida & colleagues revealed a robust relationship between psychosocial factors and atopic disorders (asthma, allergic rhinitis, atopic dermatitis, & food allergies). This supports the use of psychological in addition to conventional physical and pharmacological interventions, in the successful prevention and management of atopic disorders.  Interestingly the authors noted a bidirectional effect with a positive association between psychosocial factors and future atopic disorder as well as between atopic disorders and future poor mental health.  Finally, in two separate papers, Hamer et al report an approximately 20-25% reduction in the risk of developing Altzheimer's or Parkinson's disease in those taking very regular exercise, and also a dose-response effect of exercise on mental health.  This second study noted Different types of activities including domestic (housework and gardening), walking, and sports were all independently associated with lower odds of psychological distress, although the strongest effects were observed for sports. Conclusion: Mental health benefits were observed at a minimal level of at least 20 minutes per week of any physical activity, although a dose-response pattern was demonstrated with greater risk reduction for activity at a higher volume and/or intensity.

Chida, Y., M. Hamer, et al. (2008). "Do stress-related psychosocial factors contribute to cancer incidence and survival?" Nat Clin Pract Oncol 5(8): 466-75.  [PubMed]
A substantial body of research has investigated the associations between stress-related psychosocial factors and cancer outcomes. Previous narrative reviews have been inconclusive. In this Review, we evaluated longitudinal associations between stress and cancer using meta-analytic methods. The results of 165 studies indicate that stress-related psychosocial factors are associated with higher cancer incidence in initially healthy populations (P = 0.005); in addition, poorer survival in patients with diagnosed cancer was noted in 330 studies (P <0.001), and higher cancer mortality was seen in 53 studies (P <0.001). Subgroup meta-analyses demonstrate that stressful life experiences are related to poorer cancer survival and higher mortality but not to an increased incidence. Stress-prone personality or unfavorable coping styles and negative emotional responses or poor quality of life were related to higher cancer incidence, poorer cancer survival and higher cancer mortality. Site-specific analyses indicate that psychosocial factors are associated with a higher incidence of lung cancer and poorer survival in patients with breast, lung, head and neck, hepatobiliary, and lymphoid or hematopoietic cancers. These analyses suggest that stress-related psychosocial factors have an adverse effect on cancer incidence and survival, although there is evidence of publication bias and results should be interpreted with caution.

Andersen, B. L., H.-C. Yang, et al. (2008). "Psychologic intervention improves survival for breast cancer patients." Cancer 113: 3450-3458.  [Abstract/Full Text] 
The question of whether stress poses a risk for cancer progression has been difficult to answer. A randomized clinical trial tested the hypothesis that cancer patients coping with their recent diagnosis but receiving a psychologic intervention would have improved survival compared with patients who were only assessed.  A total of 227 patients who were surgically treated for regional breast cancer participated. Before beginning adjuvant cancer therapies, patients were assessed with psychologic and behavioral measures and had a health evaluation, and a 60-mL blood sample was drawn. Patients were randomized to Psychologic Intervention plus assessment or Assessment only study arms. The intervention was psychologist led; conducted in small groups; and included strategies to reduce stress, improve mood, alter health behaviors, and maintain adherence to cancer treatment and care. Earlier articles demonstrated that, compared with the Assessment arm, the Intervention arm improved across all of the latter secondary outcomes. Immunity was also enhanced.  After a median of 11 years of follow-up, disease recurrence was reported to occur in 62 of 212 (29%) women and death was reported for 54 of 227 (24%) women. Using Cox proportional hazards analysis, multivariate comparison of survival was conducted. As predicted, patients in the Intervention arm were found to have a reduced risk of breast cancer recurrence (hazards ratio [HR] of 0.55; P = .034) and death from breast cancer (HR of 0.44; P = .016) compared with patients in the Assessment only arm. Follow-up analyses also demonstrated that Intervention patients had a reduced risk of death from all causes (HR of 0.51; P = .028).  Psychologic interventions as delivered and studied here can improve survival..

Chida, Y., M. Hamer, et al. (2008). "A bidirectional relationship between psychosocial factors and atopic disorders: a systematic review and meta-analysis." Psychosom Med 70(1): 102-16.  [PubMed]
OBJECTIVE: There is growing epidemiological literature focusing on the bidirectional association between psychosocial factors and atopic disorders, but no efforts to quantify the relationship systematically have been published. METHODS: We searched Medline, PsycINFO, Web of Science, and PubMed up to June 2007. The studies included were prospective cohort studies investigating the influence of psychosocial factors on atopic disorders and the effect of atopic disorders on mental health. Two investigators independently extracted data and determined study quality. RESULTS: There were 43 studies (in 22 articles), of which 34 evaluated the effect of psychosocial factors on atopic disorders and 9 evaluated the effect of atopic disorders on mental health. The major atopic disease assessed in these studies was asthma (90.7%) with allergic rhinitis, 4.7%; atopic dermatitis, 2.3%; and food allergies, 2.3%. The overall meta-analysis exhibited a positive association between psychosocial factors and future atopic disorder (correlation coefficient (r) as combined size effect .024; 95% confidence interval, 0.014-0.035; p < .001) as well as between atopic disorders and future poor mental health (r = .044, 95% confidence interval, 0.021-0.067, p < .001). More notably, the subgroup meta-analysis on the healthy and atopic disorder populations showed psychosocial factors had both an etiological and prognostic effect on atopic disorders. CONCLUSIONS: The current review revealed a robust relationship between psychosocial factors and atopic disorders. This supports the use of psychological in addition to conventional physical and pharmacological interventions, in the successful prevention and management of atopic disorders.

Hamer, M. and Y. Chida (2008). "Physical activity and risk of neurodegenerative disease: a systematic review of prospective evidence." Psychol Med: 1-9.   [PubMed]
BACKGROUND: The association between physical activity and risk of neurodegenerative diseases is not well established. We therefore aimed to quantify this association using meta-analytical techniques.MethodWe searched Medline, the Cochrane Database of Systematic Reviews and Web of Science databases from 1990 to 2007 for prospective epidemiological studies of physical activity and incident dementia, Alzheimer's and Parkinson's disease. We excluded studies of physical activity and cognitive decline without diagnosis of a neurodegenerative disease. Information on study design, participant characteristics, measurement of exposure and outcome variables, adjustment for potential confounding, and estimates of associations was abstracted independently by the two investigators. RESULTS: We included 16 prospective studies in the overall analysis, which incorporated 163797 non-demented participants at baseline with 3219 cases at follow-up. We calculated pooled relative risk (RR) using a random effects model. The RR of dementia in the highest physical activity category compared with the lowest was 0.72 [95% confidence interval (CI) 0.60-0.86, p<0.001], for Alzheimer's, 0.55 (95% CI 0.36-0.84, p=0.006), and for Parkinson's 0.82 (95% CI 0.57-1.18, p=0.28). CONCLUSIONS: Our results suggest that physical activity is inversely associated with risk of dementia. Future studies should examine the optimal dose of physical activity to induce protection, which presently remains unclear.

Hamer, M., E. Stamatakis, et al. (2008). "Dose response relationship between physical activity and mental health: The Scottish Health Survey." Br J Sports Med.  [PubMed]
OBJECTIVES: Regular physical activity is thought to be associated with better mental health, although there is lack of consensus regarding the optimal amount and type of activity to achieve these benefits. We examined the association between mental health and physical activity behaviours among a representative sample of men and women from the Scottish Health Surveys. METHODS: Self reported physical activity was measured and the General Health Questionnaire (GHQ-12) was administered in order to obtain information on current mental health. Participants were 19 842 men and women. We calculated risk estimates per category of physical activity sessions per week using logistic regression models. RESULTS: Psychological distress (based on a score of 4 or more on the GHQ-12) was evident in 3200 participants. Any form of daily physical activity was associated with a lower risk of psychological distress after adjustment for age, gender, social economic group, marital status, body mass index, long standing illness, smoking, and survey year (OR = 0.59, 95% CI, 0.52-0.66, P < 0.001). A dose-response relationship was apparent, with moderate reductions in psychological distress with less frequent activity (OR = 0.67, 0.61-0.75). Different types of activities including domestic (housework and gardening), walking, and sports were all independently associated with lower odds of psychological distress, although the strongest effects were observed for sports (OR=0.67, 0.54-0.82). CONCLUSION: Mental health benefits were observed at a minimal level of at least 20 minutes per week of any physical activity, although a dose-response pattern was demonstrated with greater risk reduction for activity at a higher volume and/or intensity.