Defensiveness and perception of external inspiratory resistive loads in asthma.

This study examined the relationship between defensiveness, as measured by the Marlowe-Crowne Social Desirability Scale (MCSDS), and the perception of an externally applied respiratory resistance among people with asthma. Thirty asthmatic adults breathed through nine levels of inspiratory resistive load. Participants higher on the MCSDS were less accurate than others in psychophysical magnitude estimates of resistive load, and showed a reduced relationship between the physical load and the quality of respiratory sensations associated with exposure to the resistors. Defensive subjects also showed a differentially high increase in correlation between unpleasantness of respiratory sensations and resistance levels after receiving parenteral naloxone. These findings are consistent with the hypothesis that defensiveness may increase risk of asthma morbidity, due to inaccuracy in detecting sensations of dyspnea during asthma exacerbations. The inaccuracy may be caused by elevated endogenous opioids among defensive individuals.