Want your asthma to improve? Cultivate a positive outlook, researchers say.

An asthma patient’s level of optimism or pessimism can influence how their symptoms progress, a new study says.

People who expect their asthma and health to get worse wind up reporting more symptoms over time, researchers reported recently in the journal Health Expectations.

This wasn’t just in patient’s heads, either. Negative expectations were associated with a greater decline in actual lung function, researchers found.

On the other hand, people optimistic about their outlook experienced a slower progression of their asthma, results show.

“Explicit expectations were strongly associated with symptom outcomes, with optimistic expectations linked to clinical improvements and negative expectations predicting worsening symptoms,” concluded the research team led by Francisco Pagnini, a professor of clinical psychology at Catholic University of the Sacred Heart in Milan.

For the study, researchers tracked 310 people diagnosed with asthma for six months.

The team had patients fill out a questionnaire to gauge their feelings about how their asthma would proceed, including explicit expectations of their future symptoms and health.

Participants also performed lung function tests at regular intervals, and filled out symptom charts.

More negative expectations predicted both worse symptoms and declining lung function, researchers found.

“The hypothesis suggested to explain these results is that, as with the placebo effect, what happens is that if I have an idea about the world and the future that awaits me, that idea will prevail, largely influencing behavior and thus, for example, modifying adherence to therapies and clinical recommendations,” Pagnini said.

In other words, people who expect their asthma to get worse are less likely to follow their doctor’s advice or stick with treatments that improve their condition.

However, researchers said this study should be replicated to confirm its results and gain a deeper understanding of exactly how a patient’s expectations influence their future health.