MSACD Project: Effects of Prenatal Alcohol Exposure: What do we know?
The MSACD study of effects of prenatal alcohol on development has been in place for over 20 years. It has been federally-funded and is just one of the studies completed in the MSACD laboratory. In this section we will provide a little information about the study and summarize the findings.
When was the study done?The study began in the early 1980’s before a lot of information was available about effects of prenatal alcohol exposure (PAE) on children. Both children whose mothers drank alcohol during pregnancy and children whose mothers did not were included in the study. Since that time, the children and their mothers have continued to participate. After the initial study in infancy, subsets of the sample were seen in early childhood. Large-scale follow-ups were completed when the children were seven years of age, when they were teenagers, and in early adulthood. Additional studies are planned
Who was in the study?
Pregnant women were recruited at a hospital serving a predominantly low income, African-American community. The original sample included children whose mothers used alcohol during pregnancy as well as children whose mothers did not. When mothers were recruited, usually during the second trimester, they were provided with information that drinking and drug use during pregnancy could be harmful to the infant. They were urged not to use substances in pregnancy (Link to Smith et al., 1986; Coles et al. 1985). Whether the drinking mothers stopped or continued drinking was made part of the study.
Two additional comparison groups were added to the study over time:
When the children were seven years old, we added a group diagnosed with attention-deficit-hyperactivity disorder (ADHD). With this group, the researchers could compare the attention problems related to ADHD to those experienced by children with prenatal alcohol exposure.
When they were about 15 years old, we added a group of teenagers who were enrolled in special education classes. This group was added to control for the influence of disability status on outcomes. This Special Education Contrast group helps the researchers understand the unique effects of prenatal alcohol exposure.
What aspects of development were studied?
The researchers studied many aspects of development. In the early years, the focus was on physical development, for instance, weight and head circumference. Prenatal exposure can affect facial features and cause other kinds of birth defects. The researchers developed an instrument (checklist) to measure these physical features. Infant behavior such as motor performance, orienting behavior, and state regulation also were studied.
At school-age and later, the focus of the study changed. to intellectual development, attention, and social development. Behavior problems, peer relations, and substance use also were concerns, especially at the older age levels. Through adolescence, researchers interviewed mothers or current caregivers about the home situation to see whether characteristics of the environment affected development. At adulthood, the researchers asked permission to interview someone who knew the participant well. This person was called the collateral. Often the collateral was the mother, but could also be another relative, spouse, or friend.
In early adulthood, the researchers studied brain structure and function. They did this by using magnetic resonance imaging techniques (MRI). These brain scans were collected in addition to the social and psychological variables studied all along. These studies have helped us understand how the brain works when it has been affected prenatally by alcohol.
What is important about this study?
The sample is unusual for several reasons:People have been followed since birth. Information on maternal substance use was collected during pregnancy. Participants have been evaluated at several points in time between infancy and early adulthood.
The sample includes both exposed and non-exposed individuals. Alcohol-exposed participants can be compared to non-exposed participants recruited from the same type of urban community and at the same point in historical time.
People were recruited from the community rather than from a clinic, so the sample includes individuals who are exposed, but less affected than participants in a clinic sample might be. This allows for analysis of effects of a range of alcohol exposure, not just heavy exposure.
The data set now includes information on brain structure and function. This information was collected through brain–imaging sessions. It can be related to other physical and psychological variables collected throughout the study.
How was this study funded?
The researchers received grants from the State of Georgia and the March of Dimes in the early years of the study. Beginning with the 7-year-old follow-up, funding was provided by the National Institute on Alcoholism and Alcohol Abuse (NIAAA), one of the National Institutes of Health.
What have the researchers found out about effects of prenatal alcohol exposure?
Researchers have studied many different aspects of development through the lives of the individuals in the study. Children were first studied as infants and the study has continued to early adulthood. Below is a description of how the participants were grouped to make sense of the results; a short description of the findings in several areas of development also is included.
How were participants grouped for analyses?
In the studies when the children were still young, the groups studied were based on maternal reports of drinking in pregnancy. Usually, children of three groups of mothers were studied:
mothers who did not drink in pregnancy;
mothers who drank at the beginning of pregnancy, but stopped after an intervention (mothers were told about possible harm of substance use in pregnancy) at the prenatal interview;
mothers who drank throughout pregnancy.
For adolescents and adults, four groups were studied. For participants who were recruited at birth, two variables were used in combination to define the groups:
1) maternal report of drinking during pregnancy and
2) ratings of physical features related to prenatal alcohol exposure. These ratings are called dysmorphia scores.
Three groups from the original sample were created. In addition, the Special Education Contrast group was added at adolescence to control for disability status. The four groups used to analyzed information from adolescent and adult time frames are:
1) Control. Mothers did not drink during pregnancy;
What are the results of the study to date?
Infants of mothers who drank throughout pregnancy were smaller in weight, length, and head circumference than infants whose mothers did not drink at all.
Alcohol-exposed infants can be identified at birth through assessment of growth and specific physical features such as small eye openings or a thin upper lip. These features have been included in a measure called the Dysmorphia Checklist. It has been used by the researchers throughout the study.
Effects of prenatal alcohol exposure on growth can be identified at birth, in childhood, and in adulthood. Growth variables did not show significant differences due to prenatal alcohol exposure at adolescence. It is possible that the lack of effect at this time is due to variation in timing and rate of pubertal change.
The researchers have looked at the relationship between how much the mother drank during pregnancy and the child’s score on the Dysmorphia Checklist. A positive relationship was identified. The more the mother drank, the higher the dysmorphia score. This relationship occurred from birth through adulthood. It is called a dose-response relationship.
Intellectual development and academic achievement:
Prenatal alcohol exposure has been linked to difficulties with arithmetic and thinking about math problems. Deficits in math achievement were found in childhood and adolescence. Programs are being developed to help children with math skills.
Through magnetic resonance imaging (MRI) studies, the researchers are studying how prenatal alcohol exposure affects the brain. With this method, they can study pictures of how the brain works when participants work on math problems or complete other thinking tasks.
Prenatal alcohol exposure has been related to problems with memory. The researchers have studied how well participants complete memory tasks at several time points.
Results from childhood and adolescence suggested that memory is affected in a complex way. For instance, in childhood and adolescence, the most severely affected participants had problems with memory for pictures or visual input, but not with memory for words or stories. Studies at later follow-up points, however, suggest that both kinds of memory are affected.
Attention has been studied at several points in time with this group. When the children were 7 years old, those affected by prenatal alcohol exposure were compared to children with attention deficit hyperactivity disorder (ADHD). Tasks were included to measure four aspects of attention described by Mirsky (1991). The alcohol-affected group (FAS/E) had more problems in two areas: encoding and shifting attention. The ADHD group had more difficulty with two other areas: focusing and sustaining attention. These results suggest that attention problems of alcohol-affected children are not the same as those experienced by children with ADHD.
Attention problems seem to be more pronounced when visual stimuli are used. In the teen follow-up, sustained attention was examined using a vigilance task where letters were presented and the teen had to respond in specific situations. Both visual (letters viewed on screen) and auditory (letters heard) stimuli were presented. For the participants overall, task performance was better for the visual form of the task. For the Dysmorphic participants, however, performance was better when stimuli were heard.. These results suggest difficulties with visual attention may be a characteristic effect of prenatal alcohol exposure.
In the adult part of the study, the researchers studied the brain and how it works during a visual sustained attention task. Two parts of the results were important. First, dysmorphic participants showed a significant reduction in brain volume in the occipital-temporal area. Second,, there was less activation in the ventral occipital-temporal area. This area is involved in perception of objects. These results are important because they show both structural and functional effects on approximately the same area of the brain.
There has been a great deal of concern about the relation between prenatal exposure to alcohol and later substance use in offspring. Substance use was examined at the adolescent and the adult follow-up. Prenatal alcohol exposure did not appear to be strongly related to drug or alcohol use in later life.
At adolescence, there was no significant relationship between prenatal exposure and drug or alcohol use. Rates of use were lower than those reported at the time for national samples.
Teens who were more likely to use alcohol were older and more likely to have a mother who used marijuana during pregnancy. They also were likely to receive less parental supervison.
For the young adults, there were no significant relationships between prenatal exposure and urine tests for drug use. The urine test for marijuana was positive for 37.8% of the sample of adults. When the adults were asked about drug use, those in the Dysmorphic and Special Education groups were more likely to report currently using tobacco and marijuana.
In early adulthood, there was no relation between prenatal exposure and self-reported alcohol use. When amount of use was examined, participants in the Special Education group reported using more alcohol than those in the Control group. The two alcohol-exposed groups reported amounts intermediate between them. It is worth noting, that none of the average amounts reported were high for any group; they ranged from a little over 1 drink per week for the Control group to a little over 5 drinks per week for the Special Education group.
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