Teen drinking can have lasting effect on memory
Researchers at Duke University Medical Center say that repeated consumption of alcohol during adolescence may cause long-lasting changes to parts of the brain that control learning and memory. The findings were published in the journal Alcoholism: Clinical & Experimental Research.
The research team exposed young rats to high levels of alcohol that would cause impairment in humans, but not sedation. The rats were not exposed to alcohol again. Once those rats matured into adulthood, they had greater difficulty with memory tasks compared to rats that were not exposed to alcohol--even though the first group of the rats had not consumed it since adolescence.
Small electrical stimuli were applied to the hippocampus—the region of the brain responsible for memory and learning—to measure a cellular mechanism called long-term potentiation, or LTP. LTP strengthens brain synapses that are involved with learning new tasks and memories. The stronger these neuron signals are, the more effective the brain is at learning.
The researchers found LTP in the rats exposed to alcohol was hyperactive compared to rats that were not exposed to alcohol. This hyperstimulation of the LTP circuit prevents it from working optimally because the brain reaches a point where it can’t produce any more LTP for a period of time and the animal will stop learning. This LTP abnormality was also accompanied by a structural change in individual nerve cells. Tiny protrusions from the branches of the cells, called dendritic spines, appeared immature because they were long and thin, compared to the mushroom look they are supposed to have. The researchers also found structural changes in regions of the brain that control impulsiveness and emotionality.
The scientists say the brain is still developing at the age of 18, even though humans are considered adults by that age, and continues to develop into the mid-20s. Consuming alcohol during this time period may have a significant impact because the brain is still in the development stages. Additional studies will explore how alcohol disrupts the maturation process of cells and the long-term effects it has on cognitive function.