Wednesday, February 10, 2010
Kids' Sweet Tooth Linked to Alcoholism, Depression
A new study finds that children are more likely to have an intense sweet tooth if they have a family history of alcoholism, or if they've suffered from depression themselves.
The research was conducted by scientists at the Monell Chemical Senses Center in Philadelphia, and published online in the journal Addiction.
Sugary foods and alcohol trigger many of the same reward circuits in the brain, so scientists in this case decided to test the sweet tooth of children with a family history of alcohol dependence. They also hypothesized that children who suffer from depression might be more likely to crave sweets, because they make them feel better.
The study involved 300 children between the ages of 5 and 12. About half of them had a family history of alcoholism, defined as having a parent, sibling, grandparent, aunt or uncle diagnosed with alcohol dependence. About a quarter of the children were classified as showing depressive symptoms.
Researchers gave the children five different sweetened water samples, with varying levels of sugar saturation, and asked them which one they liked best. The children who preferred the sweetest sample were also the ones who had both a family history of alcoholism, as well as symptoms of depression.
The findings suggest that a preference for sweets might not be solely about taste buds, but instead could have to do with the child's chemical makeup and family history.
"We know that sweet taste is rewarding to all kids and makes them feel good," the study's lead author, Julie Mennella, said in a news release from Monell, where she works as a developmental psychobiologist. "In addition, certain groups of children may be especially attracted to intense sweetness due to their underlying biology."
Previous studies have illustrated a link between adult alcoholism and a sweet tooth. But other research has also shown that children's preference for sweet drinks coincides with growth spurts, rather than any underlying family biology.
For the 37 children in this study who had both the alcoholism and depression factors, the level of sweetness they most preferred was a solution with 24 percent sugar – the equivalent of about 14 teaspoons of sugar dissolved in a cup of water. That's more than twice the level of sweetness in a typical can of cola.
It was also a third more intense than the sweetness level preferred by the other children without the same family history, which was an 18 percent solution.
The study is careful to note that children with a sweet tooth won't necessarily grow up to become alcoholics or suffer debilitating depression. "At this point, we don't know whether this higher 'bliss point' for sweets is a marker for later alcohol use," Mennella said.
She and her colleagues also measured the ability of sweets to mitigate pain, by timing how long the children could keep their hand submerged in a tub of cold water while holding a sugary substance in their mouth. The sweets worked best for the non-depressed children, who kept their hands in the cold water for 36 percent longer.
"It may be that even higher levels of sweetness are needed to make depressed children feel better," Mennella said.
An outside expert at the U.K.'s Cardiff University, professor Tim Jacob, told the BBC the Monell study's findings were interesting, but that it's tough to make firm conclusions from one study alone. The results could reveal something about children's brain chemistry, but also might be explained by behavior and upbringing, he said.
"While it is true that sweet things activate reward circuits in the brain, the problem is that sweets and sugar are addictive, because the activation of these reward circuits causes opioid release, and with time more is needed to achieve the same effect," Jacob said. "But the taste difference may be explained by differences like parental control over sweet consumption."
The Monell research received funding from the National Institute on Alcohol Abuse and Alcoholism and the National Institute of Child Health and Human Development.