Sam Hening is not your average 14-year-old boy—he has Down syndrome, which leads to mental retardation and developmental delay. But after participating in a Duke University Medical Center study that examined a drug that could treat Down syndrome, Sam became more expressive and his memory improved—in the researchers’ minds, a success.
The preliminary clinical trial, published in the American Journal of Medical Genetics Oct. 15, investigated the potential use of the drug donepezil hydrochloride, a treatment for Alzheimer’s disease, to boost patients’ learning capacities. In both Down syndrome and Alzheimer’s, the lack of a certain chemical in the brain causes learning and memory difficulties.
The drug treatment has shown promise for maximizing patients’ mental capacities, although it does not address any of the other health issues. “Results suggest that there could be an expressive language improvement due to an improvement in memory, mood and attention,” said Dr. Priya Kishnani, study investigator and co-director of the Down syndrome clinic at Duke.
Down syndrome, the result of an extra copy of chromosome 21, is the most frequent genetic cause of mental retardation worldwide and affects one in every 800 live births. Individuals with Down syndrome exhibit mild to severe mental retardation and tend to suffer from other medical conditions, including thyroid and heart disease.
In patients with Down syndrome, as in those with Alzheimer’s disease, the drug directly affects the parts of the brain that are related to learning and development. Although the drug prevents further decline in patients with Alzheimer’s disease, DUMC’s 22-week trial studied the drug’s success in improving cognition in children with Down syndrome, Kishnani said.
The trial tracked seven children with Down syndrome between the ages of eight and 13. The investigators found significant improvements over the children’s pre-study performance on a language test. Before the study, the children’s average test score was equivalent to that of a child four years and three months old. After 16 weeks of treatment with donepezil, that score increased to an average level of four years and seven months old, the researchers reported.
The children’s most significant improvement was in their word and sentence structure. Although the researchers found some children’s test scores improved substantially, other children’s scores after treatment did not improve at all.
Suzanne Hening, Sam’s mother, kept a journal at home to record her own observations of her son throughout the course of the study, to supplement the researchers’ tests.
“We wrote down anything he came up with out of the blue as well as physical sickness—you don’t know if changes are real or imagined,” she said.
The researchers said more testing was necessary before doctors could prescribe the drug to children with Down syndrome. Since the children and their families were aware that they were receiving donepezil, a placebo effect and other study biases were possible.
“This was an open study for safety reasons,” Kishnani said.”An open study for adults yielded similar results but we are still trying to get funding for a double-blind study for children.
Dr. Kendall Morgan, a spokesperson for DUMC, said the researchers were already working on a larger trial to confirm the initial trial’s results.
Although she said she loves her son as he is, Suzanne Hening said she hoped the donepezil treatment would prove successful.
“I appreciate Dr. Kishnani’s work,” she said. “If there are similarities between people with Alzheimer’s and Down syndrome and the drug can truly help them become more expressive, then that’s a great thing.”
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