Smokers with a history of anxiety disorders are less likely to quit the habit than other smokers, according to a new study from the University of Wisconsin Center for Tobacco Research and Intervention.

About 1,500 smokers participated in the study, and the prevalence of anxiety among these smokers was high — about one-third of them had at least one anxiety disorder in their lifetime. In the general population, about 16.6 percent of adults develop an anxiety disorder during their lifetime.

The smokers with a history of anxiety had a harder time quitting than smokers who didn't have a history of anxiety disorders, the study said.

Those with anxiety disorders who were able to quit had higher levels of nicotine dependence and withdrawal symptoms before quitting, compared with smokers who didn't have anxiety disorders. The anxious smokers also experienced more negative feelings on their quitting day than smokers without a history of anxiety, the study said.

Among the smokers in the study, 455 had a panic attack in the past, 199 had a social anxiety disorder and 99 had a generalized anxiety disorder.

Nicotine lozenges and patches — used alone or together — failed to help patients with an anxiety disorder quit smoking. But among the smokers who didn't use to have an anxiety disorder, these smoking-cessation aids helped them quit.

The smokers also took the drug bupropion (Zyban), a depression medication that can be used to help people stop smoking, but it did not help the smokers with a history of anxiety to quit smoking, either.

"Further research is needed to identify better counseling and medication treatments to help patients with anxiety disorders to quit smoking," study researcher Megan Piper said in a statement.

The findings suggest doctors should learn whether their patients have a history of anxiety disorders when helping them to quit smoking, the study said.

While anxiety medications alone haven't boosted cessation rates, Piper said she is planning further research to test other counseling and medications to help patients who have had anxiety to quit.

The study was published online Oct. 25 in the journal Addiction.