A review of more than 50 clinical trials has found that psychological and behavioural therapies may serve as effective non-drug treatments for reducing disease-causing inflammation in the body. The results of the meta-analysis also show that cognitive behaviour therapy, or CBT, is superior to other psychotherapies at boosting the immune system.
The study’s senior author is Dr George Slavich, director of the University of California – Los Angeles (UCLA) Laboratory for Stress Assessment and Research. Along with two of his colleagues at University of California – Davis and San Diego State University, the team looked at whether interventions typically used for treating mental health problems, such as anxiety and depression, might also boost biological processes involved in physical health. They further analysed the duration and types of psychotherapy received, including group versus non-group therapy. Finally, they examined how the treatments affected different markers of inflammation and other immune system processes in the body.
"People automatically go to medication first to reduce chronic inflammation, but medications can be expensive and sometimes have adverse side effects," Slavich said. "In this review, we wanted to know whether psychotherapies can also affect the immune system and, if so, which ones have the most beneficial effects over the long term."
The researchers analysed randomised clinical trials that investigated the effects of several different types of interventions, including CBT, CBT plus medication, grief and bereavement support, a combination of two or more psycho-therapies, and psycho-education, among others.
"This seems to be a case of mind over matter," Slavich said. "Psychotherapies like CBT can change how we think about ourselves and the world, and changing these perceptions can in turn affect our biology. The results of this study take this idea one step further and suggest that psychotherapy may be an effective and relatively affordable strategy for reducing individuals' risk for chronic diseases that involve inflammation."
Through their analyses, the researchers sought to better understand how the body reacts to non-drug treatments for chronic inflammation, which increases the risk of developing several deadly diseases and can lead to premature death.
They looked at several different immune outcomes. Of those outcomes, pro-inflammatory cytokines were most strongly affected by psychotherapy in general and CBT in particular. Pro-inflammatory cytokines are notable because they help the immune system heal physical wounds and battle infections. If these proteins remain persistently elevated, though, they can lead to chronic inflammation, which increases the risk of physical illnesses, such as heart disease, cancer and Alzheimer's disease, as well as mental health problems, including anxiety disorders, depression, PTSD, schizophrenia, self-harm and suicide.
"There are many people who would prefer to use non-drug interventions for improving their immune system function," Slavich said. "In some cases, they can't take certain medications because of medical reasons, and in other instances the medications they need are too expensive. And then there are people who simply prefer a more holistic approach to improving their health."
Slavich said that these findings provide strong evidence that psychotherapy may be helpful in this regard.
"Out of all of the interventions we examined, CBT was the most effective for reducing inflammation, followed by multiple or combined interventions," Slavich said. "Moreover, we found that the benefits of CBT on the immune system last for at least six months following treatment. Therefore, if you're looking for a well-tested, non-drug intervention for improving immune-related health, CBT is probably your best choice."
Importance: Recent estimates suggest that more than 50% of all deaths worldwide are currently attributable to inflammation-related diseases. Psychosocial interventions may represent a potentially useful strategy for addressing this global public health problem, but which types of interventions reliably improve immune system function, under what conditions, and for whom are unknown.
Objective: To address this issue, we conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) in which we estimated associations between 8 different psychosocial interventions and 7 markers of immune system function, and examined 9 potential moderating factors.
Data Sources: PubMed, Scopus, PsycInfo, and ClinicalTrials.gov databases were systematically searched from February 1, 2017, to December 31, 2018, for all relevant RCTs published through December 31, 2018.
Study Selection: Eligible RCTs included a psychosocial intervention, immune outcome, and preintervention and postintervention immunologic assessments. Studies were independently examined by 2 investigators. Of 4621 studies identified, 62 were eligible and 56 included.
Data Extraction and Synthesis: Data were extracted and analyzed from January 1, 2019, to July 29, 2019. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline was followed. Data were extracted by 2 investigators who were blind to study hypotheses and analyses, and were then analyzed using robust variance estimation. Analysis included 8 psychosocial interventions (behavior therapy, cognitive therapy, cognitive behavior therapy [CBT], CBT plus additive treatment or mode of delivery that augmented the CBT, bereavement or supportive therapy, multiple or combined interventions, other psychotherapy, and psychoeducation), 7 immune outcomes (proinflammatory cytokine or marker levels, anti-inflammatory cytokine levels, antibody levels, immune cell counts, natural killer cell activity, viral load, and other immune outcomes), and 9 moderating factors (intervention type, intervention format, intervention length, immune marker type, basal vs stimulated markers, immune marker measurement timing, disease state or reason for treatment, age, and sex).
Main Outcomes and Measures: The primary a priori outcomes were pretest-posttest-control (ppc) group effect sizes (ppc g) for the 7 immunologic outcomes investigated.
Results: Across 56 RCTs and 4060 participants, psychosocial interventions were associated with enhanced immune system function (ppc g = 0.30, 95% CI, 0.21-0.40; t50.9 = 6.22; P < .001). Overall, being randomly assigned to a psychosocial intervention condition vs a control condition was associated with a 14.7% (95% CI, 5.7%-23.8%) improvement in beneficial immune system function and an 18.0% (95% CI, 7.2%-28.8%) decrease in harmful immune system function over time. These associations persisted for at least 6 months following treatment and were robust across age, sex, and intervention duration. These associations were most reliable for CBT (ppc g = 0.33, 95% CI, 0.19-0.47; t27.2 = 4.82; P < .001) and multiple or combined interventions (ppc g = 0.52, 95% CI, 0.17-0.88; t5.7 = 3.63; P = .01), and for studies that assessed proinflammatory cytokines or markers (ppc g = 0.33, 95% CI, 0.19-0.48; t25.6 = 4.70; P < .001).
Conclusions and Relevance: These findings suggest that psychosocial interventions are reliably associated with enhanced immune system function and may therefore represent a viable strategy for improving immune-related health.
Grant S Shields, Chandler M Spahr, George M Slavich
University of California – Los Angeles Health Sciences material
JAMA Psychiatry abstract