ANN ARBOR—You still see them huddled over their cigarettes in public doorways, despite 30 years of increasing social pressure and education about health risks. Why can’t they quit?

“There is mounting evidence that smoking is becoming increasingly concentrated in people at-risk for major depressive disorders, adult attention deficit hyperactivity disorder (ADHD), anxiety disorders and bulimia or binge-eating. People with these conditions or co-factors often use nicotine to help manage their symptoms,” according to Cynthia S. Pomerleau, a researcher with the University of Michigan Substance Abuse Research Center and the Nicotine Research Laboratory in the U-M Department of Psychiatry.

“Many of those who have given up smoking in the past appear to have been the ‘easy quits’ or casual adult smokers,” she added. “Health practitioners interested in helping patients with co-factors to quit need to develop new kinds of smoking interventions tailored to the special needs of these difficult-to-treat, at-risk populations.” Pomerleau’s findings are reported in a literature review in the April issue of Addiction.

Smoking has dropped in the U.S. adult population from 40 percent in 1965 to less than 29 percent in 1990. Despite the decline, Pomerleau said that smoking rates may level out at about 15 percent to 20 percent of the adult population.

“Nicotine produces temporary, small but reliable adjustments in a wide variety of cognitive and behavioral functions. Administered via smoking, nicotine quickly enters the brain where it affects neural regulators such as norepinephine, dopamine and serotonin, and can either sedate or stimulate depending on the timing, dosage and other factors,” Pomerleau explained.

When smokers with co-factors such as depression or binge-eating try to quit, their symptoms are exacerbated or unmasked by the absence of nicotine and persist well beyond the usual two- to three-day nicotine withdrawal period. Consequently, they are more likely to relapse than smokers with no co-factors.

Pomerleau cited a substantial accumulation of research to support her conclusions, including:

• A 1986 study of diagnostic subgroups that included 217 psychiatric outpatients and 411 non-psychiatric patients in a comparison group found that 47 percent of the 34 patients with anxiety disorder and 49 percent of the 45 patients with major depressive disorder smoked compared with 30 percent of the comparison group.

• A 1994 study conducted by Pomerleau and colleagues that found that 42 percent of men and 38 percent of women diagnosed with ADHD were current smokers—nearly twice the rate of the standard population. Also the “quit ratio” was 29 percent for the ADHD patients who had ever smoked compared with 48 percent in the general population.

• A 1991 study of 1,007 young adults found that—compared with individuals who had no psychiatric disorder—the rate of nicotine dependence was twice as high in adults with any anxiety disorder; three times as high in adults with major depression; and more than four times as high in individuals with the two disorders combined.

• A 1992 study of 1,800 women about to enter the U-M reported that less than 10 percent of the non-dieters and casual dieters smoked compared with nearly double that in the young women who reported behaviors and attitudes associated with a clinical diagnosis of bulimia nervosa. Similarly, a 1986 study of 646 10th-grade females found that 28 percent of bulimics and 32 percent of the purgers smoked regularly compared with 18 percent of the normal females.

Health professionals helping smokers with co-factors to quit smoking may have to treat the depression, anxiety, ADHD or binge-eating behaviors first or simultaneously, Pomerleau said. “A 1995 study found that Prozac helped smokers with depression to quit but it had no effect on smokers who were not depressed,” she said. “It is possible that some of these patients wouldn’t need nicotine replacement treatment once they received appropriate medications or psychotherapy for their underlying conditions.”

Pomerleau also suggested that more research be conducted regarding the potential therapeutic use of nicotine products—transdermal patches, nasal sprays or gum—to treat ADHD and conditions such as Parkinson’s and Alzheimer’s diseases. “We need more data on the possible toxic effects of nicotine to weigh against its possible therapeutic effects.

“Finally, we need to consider the potential needs of children of smokers with co-factors,” she said. “Recent twin studies suggest that the heritability of smoking is at least as high as that of alcohol, with significant genetic contributions to initiation, age of onset, amount smoked and likelihood of quitting. It may be that some families are predisposed to both smoking and depression.

“There also is good evidence of assortative mating in smokers—the tendency to find each other, marry and have children, with the nature and severity of problems experienced by smokers with co-factors being magnified in succeeding generations. Prevention efforts and early identification and treatment of the co-factor itself may be needed in these children.”