Hot-heads are often advised to take a deep breath, but a recent Harvard study suggests that they might not have the lung capacity to do it.

Researchers at the Harvard School of Public Health (HSPH) have found that high levels of hostility may lead to pulmonary function deterioration.

The study examined data gathered by the Veterans Administration Normative Aging Study on 670 men aged 45 to 86 who were assessed on the Cook-Medley Hostility Scale in 1986 and then subjected to follow-up pulmonary function examinations obtained over the course of eight years.

Researchers found that the men who were categorized as “high hostility” performed worse on every examination than less hostile men. Even when confounding variables such as smoking habits and Body Mass Index were taken into account, hostility still emerged as an independent predictor of the rate of pulmonary deterioration.

While many researchers have examined the link between stress and cardiovascular disease, this study is the first to investigate the long-term effect of negative emotions on the lungs.

Lead researcher Laura D. Kubzansky, an assistant professor of society, human development, and health at HSPH, said in a phone interview, “while we suspected that the toxic effect of mental stress was not limited to the cardiovascular system, we were surprised by how robust and definitive the data was.”

According to Kubzansky, decline in lung function is an early marker for many other prognoses, such as heart disease and Chronic Obstructive Pulmonary Disorder.

Harvard Professor of Medicine Scott T. Weiss, a co-author on the study, said that “the longitudinal character of the study is significant, because it allowed us to observe changing lung function over time, whereas the previous studies of this sort conducted were cross-sectional and therefore limited to the present state.”

According to David Sparrow, the study’s second author and the principal investigator in the VA Boston Health Care System, the findings of the study support the widespread view that negative emotions can have physiological impacts—for example, by causing chronic inflammation in the lungs.

While Kubzansky describes the results of the study as “definitive,” she says that it is too early to infer causal relationships from the data. “There is always the possibility, however slim, that the same gene causes hostility and a faster rate of pulmonary decline, or that both come about as a result of childhood adversity.”

The results of the study will be published in the October issue of Thorax, an international journal of respiratory medicine.