Both depression and anxiety disorders worsen the quality of life of asthma patients, report researchers who found that depression also affected patients' ability to control their symptoms.
Rates of psychiatric disorder have been shown to be up to six times more prevalent among asthma patients compared with rates observed in the general population, note Dr Kim Lavoie, from the University of Quebec in Montréal, Canada, and colleagues.
They suggest that "chronic negative mood states such as depression may interfere with daily self-monitoring abilities and treatment adherence, which may result in worse levels of asthma control".
The researchers determined the psychological status of 504 adults with asthma, along with their level of asthma control and quality of life.
Nearly one in three patients had a psychiatric diagnosis, which is a much higher prevalence than that for the general population, the team reports in the journal Chest. In all, 8% of asthma patients had a depressive disorder, 12% had an anxiety disorder and 11% had both depressive and anxiety disorders.
Further study revealed that both anxiety and depressive disorders worsened asthma-related quality of life, but only depressive disorders were associated with impaired asthma control.
"Results of worse asthma control in patients with depressive disorders, such as major depression or dysthymia, may occur because these patients may have more difficulty initiating and maintaining complex treatment regimens that require sustained effort, self-monitoring and self-administration," the investigators suggest.
"Given that less than 20% of patients meeting criteria for one or more psychiatric disorder were receiving some form of psychological treatment (psychotherapy or pharmacotherapy) at the time of their entry into the study also suggests a need to improve both detection and treatment of these patients," Dr Lavoie and co-workers note.
"Further studies are needed to assess the extent to which treatment of psychiatric disorders may impact asthma control and quality of life."