A study led by Johns Hopkins investigators has shown that women with a serious caffeine habit and a family history of alcohol abuse are more likely to ignore advice to stop using caffeine during pregnancy.
Withdrawal symptoms, functional impairment and craving were cited by the women as reasons they could not cut out or cut back on caffeine use.
None of the women had a current alcohol-use diagnosis, and none had been treated for alcohol problems.
"Results of this study suggest that genetic vulnerability reflected in a family history of alcoholism may also be at the root of the inability to stop caffeine use," said co-lead author Roland R. Griffiths, Ph.D., a professor in the departments of Psychiatry and Neuroscience at The Johns Hopkins University School of Medicine.
The study appears in the December issue of the American Journal of Psychiatry.
Griffiths, whose past studies of caffeine use helped establish the drug's addictive nature, collected data on caffeine and alcohol use from 44 pregnant women seeking prenatal care from a private obstetrics and gynecology practice in a suburban community. Results showed that half of the women who had both a lifetime history of caffeine dependence and a family history of alcoholism ignored their doctor's recommendation to abstain from caffeine use and consumed caffeine in amounts greater than those considered safe during pregnancy.
Women in the study without these dual risk factors were able to abstain from caffeine during pregnancy, Griffiths said.
"This study helps to validate the diagnosis of caffeine dependence as a clinically significant phenomenon," Griffiths said. "It's one thing to speculate how powerful the dependence is, but here we have an example of people who are not following physician recommendations and are unable to quit caffeine in spite of wanting to do so."
Caffeine use during pregnancy has been associated with a variety of adverse consequences, including spontaneous abortion and reduced fetal growth. Government health agencies in the United States, Canada and the United Kingdom have issued health warnings about limiting the use of caffeine during pregnancy. The U.S. Food and Drug Administration has advised pregnant women to "avoid caffeine-containing foods and drugs, if possible, or consume them only sparingly," and Health Canada and the Food Standards Agency of the United Kingdom have advised that pregnant women consume less than 300 milligrams per day of caffeine, according to the study.
Co-lead author of the study, Dace S. Svikis, a part-time associate professor in the Department of Psychiatry and Behavioral Sciences at Hopkins, emphasized the clinical implications of the study for pregnancy and other medical conditions for which caffeine use is not recommended. "While the majority of women in the study reduced their caffeine intake throughout pregnancy, the subgroup of women with both risk factors appears to require intervention in addition to instructions from their physician in order to assure caffeine abstinence," Svikis said. Svikis is also a professor of psychology at Virginia Commonwealth University in Richmond, Va.
Caffeine is the most widely used mood-altering drug in the world, with 80 percent to 90 percent of children and adults in North America regularly consuming caffeine-containing foods. Mean daily caffeine consumption among adult caffeine consumers in the United States has been estimated to be 280 milligrams per day, which is equivalent to about three 6-ounce cups of coffee or five 16-ounce bottles of cola soft drink, according to the study.
For the Hopkins-led study, a lifetime diagnosis of caffeine dependence was established using criteria listed in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The DSM-IV, published by the American Psychiatric Association, is the handbook used most often in diagnosing mental disorders in the United States and internationally, according to Griffiths.
Patients were evaluated as having a family history of alcoholism if they reported at least one first-degree relative who met the Family History Research Diagnostic Criteria (FH-RDC) for alcoholism. The FH-RDC has high reliability and validity for diagnoses of alcoholism in first-degree relatives.
Subjects had a mean age of 31.9 years, 96 percent were Caucasian, 100 percent were married, 50 percent had a four-year college degree and 23 percent reported having an advanced degree.
Fifty-seven percent had a lifetime diagnosis of caffeine dependence, and 52 percent reported having a family history of alcoholism. Thirty-two percent had both risk factors, and 23 percent had neither.