Psychosocial interventions, particularly cognitive-behavioral therapy (CBT), are associated with enhanced immune system function, new research suggests.
Results of a systematic review and meta-analysis that included 56 randomized controlled trials and more than 4,000 participants showed that over time, psychosocial interventions appeared to augment beneficial immune system function while concurrently decreasing harmful immune system function in comparison with control conditions.
“These associations were most reliable for cognitive-behavioral therapy and multiple or combined interventions and for studies that assessed proinflammatory cytokines or markers, which are key indicators of inflammation in the body,” study investigator George M. Slavich, PhD, said in an interview.
“The analysis helps address the question of which types of psychosocial interventions are most consistently associated with changes in immune system function, under what conditions, and for whom. This knowledge could, in turn, be used to inform research efforts and public policy aimed at using psychosocial interventions to improve immune-related health outcomes,” added Dr. Slavich, director of the Laboratory for Stress Assessment and Research, University of California, Los Angeles.
The study was published online June 3 in JAMA Psychiatry.
Link to serious physical, mental illnesses
There is substantial evidence that the immune system plays a role in a variety of mental and physical health problems. Such problems include anxiety disorders, depression, suicide, schizophrenia, cardiovascular disease, autoimmune disorders, and neurodegenerative diseases. It has been recently suggested that more than half of all deaths worldwide are attributable to inflammation-related conditions.
Although pharmacologic interventions can play a role in addressing inflammation, they are not without drawbacks, most notably, cost and adverse side effects.
The World Health Organization, the National Academy of Medicine, the National Institutes of Health, and other groups have emphasized the importance of addressing global disease burden through psychosocial interventions when possible.
Such recommendations are supported by scientific evidence. Previous research has shown that immune system processes are influenced by a variety of social, neurocognitive, and behavioral factors.
Given such findings, researchers have examined the effects of interventions that reduce stress or bolster psychological resources on immune system function.
However, such research has yielded conflicting findings. Some studies show that psychosocial interventions clearly enhance immunity, whereas others do not.
In addition, questions remain regarding which types of interventions reliably improve immune system function, under what conditions, and for whom.
“Research has shown that psychological factors – such as life stress, negative emotions, and social support – are associated with changes in immune system function,” Dr. Slavich noted.
“In addition, there is growing appreciation that immune system processes involved in inflammation may contribute to peoples’ risk for several major mental and physical health problems, including anxiety disorders, depression, heart disease, and autoimmune and neurodegenerative disorders.”
First study of its kind
To shed light on these potential links, the researchers conducted what they believe is the first systematic review and meta-analysis of randomized clinical trials of the effects of psychosocial interventions on immune system outcomes.
As part of the review, Dr. Slavich and colleagues estimated the associations between eight psychosocial interventions and seven markers of immune system function.
The eight psychosocial interventions were behavior therapy, cognitive therapy, CBT, CBT plus additive treatment or mode of delivery, bereavement or supportive therapy, multiple or combined interventions, other psychotherapy, and psychoeducation.
The seven immune outcomes that might be influenced by these interventions are proinflammatory cytokines and markers, anti-inflammatory cytokines, antibodies, immune cell counts, natural killer cell activity, viral load, and other immune outcomes.
The researchers also examined nine potential factors that might moderate the associations between psychosocial interventions and immune system function.
They searched a variety of databases for all relevant randomized controlled trials published through Dec. 31, 2018. Studies were eligible for inclusion if they included a psychosocial intervention and immune outcome, as well as preintervention and postintervention immunologic assessments.
The researchers identified 4,621 studies. Of these studies, 62 were eligible for inclusion; 56, which included 4,060 patients, were included in the final meta-analysis.
Results showed that psychosocial interventions were associated with enhanced immune system function (P < .001). There was relatively low heterogeneity between studies in these effect sizes, which, the investigators said, indicates that the association was relatively consistent across studies and conditions.
The meta-analysis showed that individuals who were assigned to a psychosocial intervention condition demonstrated a 14.7% improvement (95% confidence interval [CI], 5.7%–23.8%) in beneficial immune system function compared with their counterparts who were assigned to a control condition.
Similarly, participants who received psychosocial interventions demonstrated an 18.0% decrease (95% CI, 7.2%–28.8%) in harmful immune system function over time.