June 17, 2003

(Alcoholism: Clinical & Experimental Research) -- Individuals with a family history of alcoholism are known to be at greater risk of developing the disorder than those without such a family history. In order to pinpoint these individuals, researchers are searching for "markers" of alcoholism risk. Both animal and some human studies have shown an association between sweet preference and excessive alcohol intake. A study in the June issue of Alcoholism: Clinical & Experimental Research extends this research, finding that individuals with a positive paternal history (PHP) of alcoholism rate salty solutions as less pleasurable and sour solutions as more intense and less pleasurable than individuals with a negative paternal history (PHN) of alcoholism.

"Administering taste tests to offspring of alcoholics, those who have not yet developed alcoholism, is a way to examine taste perception without the possible interference of taste alterations that might occur in heavy drinkers," said Henry R. Kranzler, professor of psychiatry at the University of Connecticut Health Center and corresponding author for the study. "As research in this area has moved from evaluating alcoholics to assessing offspring of alcoholics, new studies have also expanded the investigation of taste perception to include salty, sour, and bitter tastes."

"Taste preference is an innate reaction that may be detected within minutes after birth," added Alexei B. Kampov-Polevoy, assistant professor of psychiatry at Mt. Sinai School of Medicine. "The most consistent finding that links taste preference and alcohol consumption [has been in animals,] such as rats, mice and monkeys, that are prone to [both] excessive consumption of alcohol - in quantities sufficient for the development of physical dependence - and of sweet solutions, sometimes quadrupling their normal daily fluid intake." To date, however, not all studies of alcohol and sweet preference have yielded consistent findings.

For this study, researchers recruited 112 non-alcoholic participants (62 females, 50 males), between the ages of 18 and 40, from other studies of alcoholism risk and through advertisements. Family history interviews were used to identify psychiatric disorders and alcohol dependence among first-degree family members. Of the 112, 45 were considered PHP (32 females, 13 males), 67 were PHN. All participants were given a series of salty and sour solutions in varying concentrations, and asked to rate each for intensity and pleasantness.

"PHP individuals rated the salty solutions as less pleasurable than PHN subjects," said Kranzler. "They also experienced the sour stimulus as more intense and less pleasurable than PHN subjects. These findings extend previous research by demonstrating the phenomenon of different taste characteristics among a larger and more diverse sample, and also support preliminary results from a study in Poland. We interpret these findings as evidence of unique taste perception among individuals with a paternal history of alcoholism compared to those without such a history."

Kranzler added that the implications of these findings need to be considered within the context of the study participants. "We evaluated a group of nonalcoholic offspring of alcoholic fathers," he said. "Participants were screened to exclude those who had ever experienced any alcohol, drug, and psychiatric disorders. In light of that, there are two possible explanations for our findings. First, these results could indicate that PHP individuals who are protected from alcoholism possess unique taste characteristics which contribute to this protection, that is, decreased pleasantness of salt and increased perception of intensity of sour. Alternatively, certain groups of individuals with a paternal history of alcoholism may inherit genetic alterations in taste characteristics that put them at increased risk for alcoholism. The implication of the latter explanation, altered taste characteristics, has yet to be fully explored in relation to alcoholism risk."

Taste characteristics may interact with other factors in the development of alcoholism, said Kranzler. "Sweet-taste sensitivity has been linked to impulsiveness and other related behavioral factors associated with alcoholism," he said, "but salty and sour taste differences are not as easily linked to such markers. We know that a decreased sensitivity to the intoxicating effects of alcohol appears to put one at risk of developing alcoholism. Perhaps salty and sour taste characteristics exert indirect independent effects that may be more important in the acquisition of drinking behavior, while decreased sensitivity to alcohol's intoxicating effects may influence the maintenance of drinking behavior."

Kampov-Polevoy's research has also uncovered a connection between taste characteristics and other factors, finding that combining a sweet preference test and a personality profile can predict alcoholic versus non-alcoholic status with "fair" sensitivity and "good" specificity. "These data indicate that the sweet preference itself may not be sufficient for prediction of alcoholism in humans," said Kampov-Polevoy. "However, if combined with some personality traits, it has a better predictive value regarding alcoholism," he said.

"Unlike the association between sweet preference and excessive alcohol intake," Kampov-Polevoy added, "the association between salty and sour taste and risk for alcoholism [has been] studied to a much lesser extent. If confirmed, these data may contribute to the development of physiological markers of alcoholism. For example, [we already know] there is a high correlation between sweet preference and voluntary alcohol intake. Therefore, you may take a rat that has never tasted alcohol, measure its intake of sweets, and exactly predict how much alcohol it will drink if it will be given a chance. Just imagine for a second if we [were] able to design a similar test for humans [based on our knowledge of taste perception of sweet, salty, sour and bitter.] It [would] allow us to evaluate a child's risk of becoming an alcoholic long before he or she touches an alcoholic beverage. I think it is important for the reader to know that the creation of such a test is not as far away as one might think."