Depression, smoking divulge ties that bind.

Two new studies find that avid cigarette smokers develop severe depression substantially more often than nonsmokers and, conversely, that people with a history of severe depression stand a greater chance of getting hooked on cigarettes than nondepressed individuals.

Common factors - perhaps genetically influenced personality traits or alterations in brain chemicals - appear to foster both cigarette smoking and severe depression, say the researchers.

Their results, reported in the January ARCHIVES OF GENERAL PSYCHIATRY, derive from one-year or longer follow-ups of smokers and nonsmokers. Prior studies reached similar conclusions based on volunteers' reports of past smoking and depression (SN: 6/1/91, p. 351).

Psychologist Naomi Breslau of Henry Ford Hospital in Detroit and her colleagues interviewed 995 young adults, age 21 to 30, in 1989 and again 14 months later. The predominantly white sample was recruited from a health maintenance organization in Michigan and contained more women than men. Most participants lacked a college education.

Severe depression, a cyclic and frequently incapacitating condition marked by hopelessness and despair, occurred substantially more often during the study among participants with a history of nicotine dependence, even if they had abstained from smoking during the year preceding the study, Breslau's team reports. Symptoms such as repeated failure to quit smoking and intense withdrawal reactions define nicotine dependence.

In addition, about one in 13 persons with a history of nicotine dependence suffered a first episode of severe depression during the study, more than twice the rate charted for those not citing regular cigarette use at some point in their lives. This finding emerged whether or not smokers had tried to kick their habit during the study

Conversely, smokers who had previously suffered episodes of severe depression faced a much greater likelihood of becoming dependent for the first time or more severely dependent on nicotine than smokers with no such history. Past anxiety disorders and the abuse of alcohol or illicit drugs exerted no influence on degree of nicotine dependence.

In the second study, psychiatrist Kenneth S. Kendler of the Medical College of Virginia in Richmond and his co-workers interviewed 727 pairs of female twins and 112 women whose female twin did not take part in the project. The sample consisted of slightly more identical twins (who possess the same genes) than fraternal twins (who possess about half the same genes). Volunteers averaged 31 years of age.

Women who had smoked at some time in their lives reported more previous severe depression than nonsmokers. The former group also experienced more severe depression over a one-year follow-up, regardless of past alcohol abuse or anxiety disorders. Moreover, volunteers citing previous bouts of depression smoked more during the follow-up.

In identical-twin pairs in which only one twin had a history of depression, no link between depression and smoking emerged. The same held for identical-twin pairs with only one smoker. Yet a family history of severe depression increased a woman's likelihood of smoking. and a family history of smoking boosted a woman's chances of becoming depressed.

This pattern suggests that a common genetic predisposition combines with personal experiences -- at least among women - to produce both severe depression and smoking, Kendler's group asserts.