Prenatal Exposure to Alcohol Influences Taste and Smell
> 12/13/2007 2:21:39 PM

It is well established that alcoholic parents are more likely to have alcoholic children, a sad fact that has perpetuated a cycle of abuse for much of human history. It was not clear though whether this was due to poor parenting, genetics, or a neurological change resulting from fetal exposure to alcohol. While all of these probably play a role, it was not until relatively recently that researchers found convincing evidence of a neurological change not tied to addiction. Two new studies, released concurrently by the SUNY Developmental Exposure Alcohol Research Center, shed light on specific neurological alterations that can be caused by prenatal exposure.

Both of the studies found that rats whose mothers consumed alcohol while pregnant underwent perceptual changes. One study exposed rats to alcohol in the womb and then gave them access to unlimited alcohol from a feeding tube. This group drank far more than a control group that was allowed to drink whatever it wanted. This difference held even when the alcohol-exposed group's diet was controlled to assure that all important nutrients were consumed at each meal regardless of the amount of ethanol in a meal. This finding is useful for a number of reasons. For one, it shows that genetic factors cannot be even close to the whole story. The mothers chosen for exposure were picked randomly by scientists, not self-selected by genetic predispositions. In addition, children showed a higher propensity for alcohol consumption even when separated from their mothers, demonstrating that alcoholism cannot be just a learned behavior.

This first study offers strong proof that a neurological change occurs in the fetus, but it does little to narrow in on exactly what kind of change occurs. Do rats drink more because they come out of the womb already addicted to alcohol and suffering withdrawal, or do they like the taste more? For obvious reasons, it is hard to interrogate rats about their tastes and motivations. Even so, a second study by the same authors goes far towards pinpointing the nature of neurological change.

The second study tested prenatally exposed rats' sense of smell with two methods of evaluation. The first was a chamber with carefully controlled airflow and the capability to monitor the exact levels of ethanol scent flowing through and the amount of air inhaled and exhaled by the rats. The chamber showed that exposed rats took much deeper and more frequent sniffs of ethanol in addition to displaying other obvious signs of heightened interest. The second method of evaluation directly measured the patterns of activation in the olfactory mucosa. The patterns were undeniably altered towards greater activation.

All of the heightened responses described above tapered off by adulthood. Further study is required to figure out why alcohol predisposition faded with age, but one plausible explanation is that while prenatal taste tuning is of primary importance to a child, other life experiences begin to weight in and associate more healthy food with positive results. Even though it is possible to outgrow the predisposition, prenatal exposure is still dangerous if the phenomenon observed in rats also occurs in humans. Children who are drawn to the taste and smell of alcohol are much more likely to abuse it, and if they become addicted they may continue to abuse it throughout their lives. Hopefully, these studies will reach expectant mothers and impress upon them the dire consequences that can come with any alcohol consumption during pregnancy.

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