The research provides clues that may eventually help doctors to better understand and treat aging patients, a field of increasing interest as the population bulge known as baby boomers nears retirement age.
The neurotransmitter serotonin plays an important role in learning, memory, cognition, sleep regulation and the experience of pain, anxiety and depression, according to pharmacologist Joan M. Lakoski, Ph.D., associate professor at Penn State University's Milton S. Hershey Medical Center and co-author of the study. Serotonin-enhancing drugs such as Prozac are now commonly used to treat depression, a condition marked by low levels of certain neurotransmitters.
The current study indicates that the ability to recover the serotonin function of a key part of the brain appears to decline with age, according to this female rodent model of aging. In these investigations, the researchers studied the area of the brain known as the hippocampus, and applied to it a neurotoxin that causes lesions. Young adult rats of two months were compared to an older group of 17 months.
The results indicated that the older rats had an impaired ability to compensate for the damage, "which may further be associated with deficits in cognitive function found with both normal and pathological aging," according to the article.
"With this research we've identified a specific change in a brain area which has a critical role in learning and memory," she said. "As a pharmacologist, my long-term goal is to take what we've identified and see how it gives us new therapeutic approaches to treat injuries to that region of the brain.
"The normal function is to respond to injury," said Lakoski. "But as we age our bodies are less able to compensate for damage." As the serotonin function weakens, then depression and related problems often occur. "Elderly women are particularly at risk for depression and anxiety," said Lakoski.