"Aversive learning appears to begin quite young, indeed," said Enoch Gordis, M.D., Director of the National Institute on Alcohol Abuse and Alcoholism, which supported the study. "While it remains to be seen whether and, if so, for whom early aversion persists or affects later behaviors, this work adds useful information to NIAAA’s efforts to understand why many kids get into trouble with alcohol and others do not."
Preventing underage drinking is a focus of NIAAA research and the newly established Leadership to Keep Children Alcohol Free, a multiyear outreach initiative spearheaded by state Governors’ Spouses, the Robert Wood Johnson Foundation, the Substance Abuse and Mental Health Services Administration, and NIH’s Offices of Research on Women’s Health and Minority Health.
Today’s report strongly ties very early learning about alcohol to the emotional context of parental drinking, according to first study author Julie A. Mennella, Ph.D. Her findings are consistent with animal model studies that found that rat pups exposed to an intoxicated mother later were averse to textures that they associated with an alcohol smell. Previous research also has shown that elementary-aged children of alcoholic parents report more negative alcohol expectancies than children of nonalcoholics, and that preschoolers whose parents drink heavily or to escape are more successful than other preschoolers at identifying alcohol by smell. Dr. Mennella and coauthor Pamela Garcia extend these findings to encompass children’s hedonic (pleasurable or unpleasurable) responses and are the first to show a direct aversive effect related to parental drinking
Dr. Mennella’s laboratory earlier reported [Chemical Senses 1998; 23:11-17] that 6- to 13-month-old infants with greater previous exposure to alcohol (inferred from questionnaires about parental drinking) could discriminate its smell from the smell of vanilla and that those children behaved differently in response to alcohol-scented toys. That study showed both that the alcohol smell evoked a behavioral response and that sensory learning based on smell is keenly selective, she said.
In today’s study, 83 girls and 67 boys were presented with plastic squeeze bottles, each of which contained the odor of beer, bubble gum, sour milk (pyridine), or a neutral odor (mineral oil). The researchers delivered gentle puffs of air from the squeeze bottles into the children’s nostrils and asked them if they liked or disliked the different odors. When the children liked an odor, they passed that squeeze bottle to a stuffed Big Bird toy; if they disliked an odor, they passed that bottle to an Oscar-the-Grouch toy so that he could throw it in his garbage can.
The mother and, when possible, the father answered questions about alcohol use. Parents who drank alcohol to alter their mental state or lessen feelings of unhappiness were considered escape drinkers; those who reported drinking to escape also were found to drink more alcohol than those who did not. Of the 150 children who participated in the study, 25 had mothers and 30 had at least one parent (mother, father, or both) who reported drinking to escape.
Most children (86 percent) liked the bubble gum odor and disliked (89 percent) the sour milk odor. About half (53 percent) liked the beer odor. When the researchers grouped the data according to whether the parents drank to escape, the differences were highly significant: 66 percent of children whose parents were not escape drinkers indicated they liked the beer odor while only 27 percent of the children with at least one parent who drank to escape said that they liked the beer odor. Similarly, 58 percent of children whose mothers did not drink to escape liked the beer odor while only 28 percent of children whose mothers were escape drinkers liked the odor.
"Because of a unique interconnection between the olfactory and limbic systems, memories evoked by odors are more emotionally charged than those evoked by other sensory stimuli," according to Dr. Mennella. Unlike sensory systems for sight, hearing, taste, and touch, the olfactory system has direct links with the emotional centers of the brain--the limbic system’s amygdala-hippocampus complex.
Future work will determine how such emotional responses to alcohol change with age, Dr. Mennella says. For reprints or additional information about the study, please telephone her at 215/898-9230.
For alcohol research information, please visit http://www.niaaa.nih.gov/ or telephone NIAAA Press (301/443-3860).