Study suggests that adolescent exposure to alcohol can negatively affect learning, memory and behavior in adulthood

A study at Duke University suggests that repeated exposure to alcohol during adolescence causes long-lasting changes in the part of the brain that controls learning and memory. The study, published in the journal Alcoholism: Clinical & Experimental Research, helped explain how exposure to alcohol before the brain has fully developed can cause cellular and synaptic abnormalities and negatively affect behavior. Kentucky is ranked 9th in the nation for the percentage of children who drank alcohol before age 13 (25.1 percent), according to the state Department for Public Health.

"In the eyes of the law, once people reach the age of 18, they are considered adult, but the brain continues to mature and refine all the way into the mid-20s," said lead author Mary-Louise Risher, a post-doctoral researcher in Duke's Department of Psychiatry and Behavioral Sciences. "It's important for young people to know that when they drink heavily during this period of development, there could be changes occurring that have a lasting impact on memory and other cognitive functions.

Studies had shown that animals exposed to alcohol at an early age do not perform as well in memory tasks as those not exposed to it. The new study, which involved exposing young rodents to alcohol and waiting for them to grow into adulthood, found that the exposure also affects the hippocampus, the area of the brain that controls memory and learning. The researchers measured a cellular mechanism called long-term potentiation, which involves the strengthening of brain synapses being used to learn new tasks or bring up memories. Ideally, LTP should be high, especially in young people. The researchers found that the adult rodents exposed to the alcohol during adolescence had higher levels of LTP, which may seem to be a positive outcome but is actually not.

"If you produce too much LTP in one of these circuits, there is a period of time where you can't produce any more," said senior author Scott Swartzwelder, a Duke professor. "The circuit is saturated, and the animal stops learning. For learning to be efficient, your brain needs a delicate balance of excitation and inhibition—too much in either direction, and the circuits do not work optimally."

The researchers also observed a structural change in individual nerve cells: those exposed to alcohol at a young age have brain cells that appear immature, even in adulthood. "It's quite possible that alcohol disrupts the maturation process, which can affect these cognitive functions later on," Risher said. She also noted that the immature appearance of the cells might be associated with behavioral immaturity.

Fragile X Syndrome, a little known disorder, is the leading inherited cause of intellectual disabilities; U of L has only clinic for it in Ky.

A common but little-known genetic disorder called Fragile X Syndrome is the leading inherited cause of intellectual disability, autism and developmental delay, and the University of Louisville is home to the only Fragile X clinic in Kentucky, the university said in a press release.

Varying levels of disability are associated with the syndrome, depending on whether the FMR1 gene associated with the condition is fully mutated or merely changed but not fully mutated, according to the release.

The federal Centers for Disease Control and Prevention explains that the FMR1 gene is responsible for making a protein that is needed for normal brain development. Those with the syndrome don't make this protein, and those with altered genes don't make enough of it.

Infants born with the fully mutated gene may have intellectual disability, autism and/or delays in development, speech and language. Those with altered genes are more likely to have milder problems in childhood, such as a learning disability or issues with anxiety and social difficulty, which can occur both in childhood and adulthood, says the release. They can also develop infertility and neurological problems such as tremors, imbalance and dementia. Some carriers of the altered genes have no symptoms.

Fragile X Syndrome affects one in approximately 4,000 men and 6,000 women, according to the release. Carriers of the altered gene, who pass it along to later generations, are much more common, with approximately one in 250 women and 800 men.

The Weisskopf Child Evaluation Center at U of L is home to one of 27 clinics affiliated with the National Fragile X Foundation.

John and Shannon Casasfranco had their 2-year-old son John, who had been diagnosed with autism, genetically tested at the center on their doctor's recommendation. They learned that he had Fragile X, and that they were both carriers of the altered gene.

They encourage families to speak to their doctor about genetic testing if they are concerned about children not meeting milestones or suspect that Fragile X is an issue in their family. “If we hadn’t have gotten John tested, we wouldn’t know anything. There is no blood test for autism but there is for Fragile X. Now we know there’s a biological reason for his disability. It’s a hard thing to swallow but you’ve got to plan,” Shannon said.

“Because of our affiliation with the Fragile X Clinical & Research Consortium, we can provide care to patients and families like the Casasfrancos that is based on the most up-to-date knowledge and recommendations of clinicians across the United States who have expertise in Fragile X,” Lisa Craft, ;medical director of the WCEC Fragile X clinic, said.

According to Craft, Fragile X genetic testing should be considered for:

• A child with autism or developmental delays
• Adults with autism or developmental disabilities with no known cause
• Adults with a tremor or balance problem, even if no family members have been diagnosed with Fragile X.
• Women with fertility problems, even if no family members have been diagnosed with Fragile X.

“With knowledge comes power. Knowing that a child or adult has Fragile X provides the family with a ‘road map’ to help them understand the individual’s needs, challenges and strengths,” Craft said. “A diagnosis helps families find the most appropriate services and connect to other families and professionals who can help them on their journey across the lifespan.”

July 22 is National Fragile X Day.