Research out of California’s Stanford University has uncovered three potential treatments for Down syndrome and has shed more light on how the condition works.
According to the National Down Syndrome Society, more than 350,000 people in the U.S. are currently living with “Down syndrome.” This condition is caused by the presence of an extra chromosome (a duplicate of chromosome 21), usually created by an error in division of the cells around the time of conception. It’s not yet known why this occurs, but the age at which a mother has a baby is considered a potential risk factor.
Unlike other syndromes, Down syndrome is largely recognized through physical traits, such as a smaller or differently-shaped head, flatter-looking face, small nose, eyes with an upward slant to them, skin folds on the inner corner of the eyes, a single, deep crease across the middle of the palm (rather than two), very little muscle tone, and shorter limbs and stature.
Based on these characteristics, a doctor will perform a blood test and examine the chromosomes of the patient to make a definitive diagnosis. Many (but not all) Down syndrome sufferers will also demonstrate delayed mental and/or social skills to a greatly varying degree.
There are other complications associated with this genetic condition, including congenital heart defects, vision difficulties, Alzheimer’s disease, and problems with the esophagus, duodenum or gastrointestinal system. Shockingly, Down syndrome patients are at a 15 to 20 times’ greater risk for leukemia. There is currently no treatment for the syndrome itself, just for the related health issues.
The latest research focuses on the treatment of the cognitive impairment associated with Down syndrome. It’s not yet known exactly how the genetic condition impacts the brain to cause problems with memory and learning, but it’s thought that a specific place in the brain, the “hippocampus,” is involved.
So, in this study out of California, scientists decided to try out several drugs in mice to see if the cognitive problems in Down syndrome patients could be reversed. Using some mice subjects engineered to exhibit the same type of learning and memory impairment as humans with the condition, the research team tested three drugs.
The three drugs tester were: “picrotoxin,” a plant-based toxin that can promote the function of neurotransmitters in the brain; “bilobalide,” a main component of “terpenoids” (chemicals related to scent) found in “Gingko biloba,” which you’ve probably heard of as a herbal treatment for memory problems; and “pentylenetetrazol” (PTZ), a drug once used to treat psychiatric problems and dementia. The mice were given low doses of one of these three drugs every day for two to four weeks.
The researchers found that all three of the substances greatly improved the brain function of the test mice in a task involving object recognition, which they were tested on before and after treatment. In a spontaneous alternation task, which tested the ability to navigate spatially, the rodents that had been given PZT showed significant improvement. Even two months after treatment with PZT, when tested again, the mice still showed increased mental capacity — which is great, because it means that the benefits could be long-term!
Before this study, the Stanford University scientists believed that, in Down syndrome patients, the communication between the cells in the hippocampus is disrupted, leading to imbalanced signals and, thus, problems with memory and learning. Since the three drugs chosen for the study are all known to block a certain type of signal in the hippocampus, it seems that this theory could be correct. That’s one reason that this study is so exciting; it could back up this theory, leading to greater understanding of the condition.
The other reason is obviously that there are now three new possible treatments for the cognitive problems of Down syndrome, which means the chance for greater quality of life for those born with the condition.
However, as usual, I need to point out a couple of things. Firstly, this is a study on mice, not humans. It cannot be said definitively that picrotoxin, bilobalide, or PTZ will have the same effect on us as they do on rodents; therefore, more studies into their effectiveness and safety for humans are required.
Secondly, PZT, which seemed to be the top performer in this study, was taken off the market by the Food and Drug Administration (FDA) many years ago due to the fact that it could cause seizures. Another good reason for thorough and careful testing.