A green tea compound called epigallocatechin gallate could benefit cognitive functioning for people with Down syndrome.
Study co-leader Dr. Mara Dierssen, of the Centre for Genomic Regulation (CRG) in Barcelona, Spain, and colleagues reveal how the compound epigallocatechin gallate (EGCG) improved the cognitive function of individuals with the condition.
According to the researchers, their study represents the first time a treatment has shown some improvement in cognitive skills for people with Down syndrome.
According to the National Down Syndrome Society, around 1 in every 691 babies in the United States are born with Down syndrome, and there are more than 400,000 Americans living with the condition.
Down syndrome is the most common genetic condition in the U.S., occurring when an individual has a partial or full additional copy of chromosome 21, meaning they have three copies of this chromosome, rather than the normal two.
This extra chromosome leads to overexpression of genes, which can cause a number of physical symptoms, including reduced muscle tone, a small head, ears, and mouth, a flattened facial profile, and upward-slanting eyes.
Individuals with Down syndrome may also experience problems with cognitive function, such as delayed language and speech development, learning and memory impairments, and poor concentration.
According to Dr. Dierssen and colleagues, research has shown that such cognitive impairments are down to overexpression of a gene called DYRK1A, and studies in mice have suggested the compound EGCG could reduce DYRK1A overexpression.
Now, the new study indicates that the compound could do the same for people with Down syndrome, achieving an improvement in cognitive function.
Daily dose of EGCG improved three areas of cognitive function
For their study, Dr. Dierssen and colleagues enrolled 84 individuals aged 16-34 who had Down syndrome.
- A form of Down syndrome called trisomy 21 accounts for around 95 percent of all cases
- Life expectancy for people with Down syndrome has more than doubled since the early 1980s
- Down syndrome may increase the risk of other illnesses, including congenital heart defects, respiratory problems, childhood leukemia, and Alzheimer's disease.
For 12 months, participants were randomized to receive a daily dose of decaffeinated green tea containing EGCG - 9 milligrams per kilogram - or a placebo. Both groups also underwent weekly cognitive training.
The trial was double-blind, meaning the researchers, the participants, and their families were unaware of what treatment each subject received.
All participants underwent cognitive tests and brain imaging at 3, 6, and 12 months, as well as 6 months after treatment had ceased.
Compared with participants who were treated with the placebo, the researchers found that those treated with EGCG scored much better in certain areas of cognitive function.
Specifically, they showed significant improvements in three areas:
- Visual recognition memory - the ability to remember and distinguish between objects
- Inhibitory control - the ability to resist distractions and avoid acting on first impulses
- Adaptive behavior - the ability to use conceptual, social, and practical skills for everyday functioning.
Furthermore, on assessing the brain scans of each participant, the team found that those who were treated with EGCG showed greater functional connectivity between nerve cells than those who received the placebo.
"It was surprising to see how the changes are not just cognitive - in the reasoning, learning, memory and attention capacities - but suggest that the functional connectivity of the neurons in the brain was also modified," says study co-leader Dr. Rafael de la Torre, of the Hospital del Mar Medical Research Institute in Barcelona, Spain.
Overall, the researchers believe their results indicate that EGCG may be an effective treatment for people with Down syndrome.
"This is the first time that a treatment has shown some efficacy in the improvement of some cognitive tasks in persons with this syndrome.
It must be made clear that our discovery is not a cure for Down syndrome and that our results have to be proven in larger populations, but it may be a treatment to improve these individuals' quality of life."
Dr. Mara Dierssen
As well as further trials investigating the efficacy and safety of EGCG in larger cohorts, the team plans to assess how the green tea compound may impact the cognitive functioning of children with Down syndrome.
"Our results have been already marginally positive in the adult population, in which cerebral plasticity is limited because the brain is already completely developed," the authors note. "We believe that if the treatment is applied to children, the results might be even better."