New research suggests that expectations are associated with asthma outcomes. People who thought more negatively about their condition reported worse symptoms, adding to growing evidence about the mind-body connection and its influence on health.
In both healthy and disease states, there’s a complex interplay between biological, psychological, and social factors. Studies have shown how stress, for example, can negatively affect the immune, nervous, and endocrine systems. But what about positive thinking? Is it possible for a person to slow the progress of a disease by thinking positive thoughts?
A new study led by the Catholic University of the Sacred Heart, Milan campus, suggests that it is possible. It found that people who remained optimistic following an asthma diagnosis had a slower disease progression.
The researchers explored how people’s expectations about their illness, specifically asthma, affected their symptoms and lung function over time. These expectations, which they called illness expectations (IEs), could be either explicit, conscious beliefs about one’s condition, or implicit, unconscious associations or gut-level assumptions. The researchers wanted to know whether these beliefs could actually influence how asthma progressed, even beyond the impact of stress, mood, and treatment adherence.
This longitudinal cohort study recruited 310 adult patients with a 12-month history of asthma symptoms and followed them for a period of six months. The patients were assessed at three time points: baseline, three months, and six months.
The study was heavily impacted by challenges brought about by the COVID-19 pandemic. The first challenge was that the use of spirometers, devices used to measure lung function, was discouraged or prohibited due to the risk of COVID transmission. The second was that pandemic-related psychological factors may have acted as uncontrolled confounding variables. This meant that of the 310 participants enrolled, only 102 performed complete spirometry at baseline, and final full assessments were available for 95 participants, not necessarily all with spirometry data.
Asthma symptom severity was measured using the Asthma Control Test (ACT), a brief, self-administered questionnaire comprising five questions, each scored from 1 to 5, with a total possible score ranging from 5 to 25. A lower score indicates poorer asthma control. To measure lung function, the researchers used spirometry to measure Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). The video below provides a more detailed explanation of these tests.
Explicit and implicit IEs were measured using a self-report questionnaire and the Implicit Association Test (IAT), respectively. Psychosocial variables, such as stress, anxiety/depression, health behaviors, and medication adherence, were also measured. Statistical models were used to track changes over time and to analyze how IEs might influence outcomes via other (psychosocial) variables.
The researchers found that people with more negative explicit expectations, for example, “My asthma will get worse,” had worse asthma symptoms over time (decreasing ACT scores) and declines in lung function (decreased FVC). This relationship held even after controlling for stress, mood, health habits, and medication adherence. Implicit beliefs did not significantly predict asthma outcomes. This may have been due to limitations in how well implicit beliefs were measured.
An obvious limitation of the study was the high dropout rate (69%) due to the COVID-19 pandemic and restrictions on lung function testing. This drop in numbers reduces statistical power and may introduce bias, and, for that reason, the researchers advise caution when interpreting the findings. Furthermore, self-reported symptoms may be subject to recall bias or emotional influences, especially during the pandemic. Since the study focused solely on asthma, its findings may not apply to other chronic diseases. The IAT had poor test-retest reliability, which means it produced inconsistent results when used repeatedly on the same individuals, which can significantly weaken the validity of research findings.
Nonetheless, the study provides strong evidence that what people think will happen with their illness may influence what actually happens, at least in the case of asthma symptoms. It supports the growing view that, as demonstrated by research into the placebo effect, the mind-body connection is a powerful factor in chronic disease management.
“From a clinical perspective, our results tentatively support the value of considering patients’ expectations during asthma management,” said the researchers. “Recognizing the way patients think about their illness – particularly their expectations regarding symptoms and progression – may provide insight into their health-related behavior and treatment engagement.”
Future research would benefit from developing better tools to measure implicit expectations and to investigate IEs in other chronic conditions, such as diabetes or COPD.
The study was published in the journal Health Expectations.
Source: Università Cattolica del Sacro Cuore