They are also three times as likely to be current users of the controversial battery-powered nicotine-delivery devices, as people without mental health disorders.
They are also more susceptible to trying e-cigarettes in the future in the belief that doing so will help them quit, the scientists said. The FDA has not approved e-cigarettes as a smoking cessation aid.
The study will be published in the May 13 online issue of Tobacco Control
"The faces of smokers in America in the 1960s were the Mad Men' in business suits," said lead author Sharon Cummins, PhD, assistant professor in the Department of Family and Preventive Medicine. "They were fashionable and had disposable income. Those with a smoking habit today are poorer, have less education, and, as this study shows, have higher rates of mental health conditions."
By some estimates, people with psychiatric disorders consume approximately 30 to 50 percent of all cigarettes sold annually in the U.S.
"Since the safety of e-cigarettes is still unknown, their use by nonsmokers could put them at risk," Cummins said. Another concern is that the widespread use of e-cigarettes could reverse the social norms that have made smoking largely socially unacceptable.
The study shows that smokers, regardless of their mental health condition, are the primary consumers of the nicotine delivery technology. People with mental health disorders also appear to be using e-cigarettes for the same reasons as other smokers - to reduce potential harm to their health and to help them break the habit.
"So far, nonsmokers with mental health disorders are not picking up e-cigarettes as a gateway to smoking," Cummins said.
The study is based on a survey of Americans' smoking history, efforts to quit and their use and perceptions about e-cigarettes. People were also asked whether they had ever been diagnosed with an anxiety disorder, depression or other mental health condition.
Among the 10,041 people who responded to the survey, 27.8 percent of current smokers had self-reported mental health conditions, compared with 13.4 percent of non-smokers; 14.8 percent of individuals with mental health conditions had tried e-cigarettes, and 3.1 percent were currently using them, compared with 6.6 percent and 1.1 percent without mental health conditions, respectively.
In addition, 60.5 percent of smokers with mental health conditions indicated that they were somewhat likely or very likely to try e-cigarettes in the future, compared with 45.3 percent of smokers without mental health conditions.
"People with mental health conditions have largely been forgotten in the war on smoking," Cummins said. "But because they are high consumers of cigarettes, they have the most to gain or lose from the e-cigarette phenomenon. Which way it goes will depend on what product regulations are put into effect and whether e-cigarettes ultimately prove to be useful in helping smokers quit."
Co-authors of this study include Shu-Hong Zhu and Anthony C. Gamst, Department of Family and Preventive Medicine, UCSD; Gary J. Tedeschi, UC San Diego Moores Cancer Center; and Mark G. Myers, Department of Psychiatry, UCSD.
Funding for this research came from the National Cancer Institute (grant U01 CA154280).