Current drugs are not effective in treating Fragile X syndrome as they target only one of several neurotransmitters that contribute to the disorder, according to a study published October 23. Researchers determined that to effectively treat Fragile X, a drug would need to act on several neurotransmitter systems, reports C.J. Malanga, M.D., Ph.D., of the University of North Carolina School of Medicine.
Malanga and his team used a mouse model to test three different drugs. The drugs included one drug that blocked dopamine receptors, another drug that blocked mGluR5 receptors, and another drug that blocked mAChR1, or M1, receptors. They noted that three neurotransmitters - dopamine, glutamate and acetylcholine - acted on the receptors. The research team also observed different drug sensitivities in the mice. “Fragile X kids likely have very different sensitivities to prescribed drugs than do other kids with different biological causes of autism,” Malanga said.
The researchers' findings indicate that each person with Fragile X syndrome may respond differently to any specific drug. “There likely won’t be one magic bullet that really helps people with Fragile X,” said Malanga. “It’s going to take therapies acting through different receptors to improve their behavioral symptoms and intellectual outcomes.”
Fragile X syndrome explained
Fragile X syndrome causes learning disabilities and cognitive impairments, according to the National Institutes for Health. It is an inherited condition that affects almost 1 million people in the United States. Fragile X syndrome is caused by mutations in the gene FMR1.
Fragile X affects both sexes although it is usually more severe in boys than girls. The March of Dimes indicates that symptoms of Fragile X can vary, but typically include intellectual disabilities, behavioral problems, autistic like behaviors and sensitivity to light, touch and sound .
There is no cure for Fragile X syndrome. Typical treatments for the disorder include occupational therapy, speech and language therapy, physical therapy and psychological therapy. Some children take antidepressants or other drugs to help with behavioral issues.
Neurotransmitters and Fragile X
Neurotransmitters are chemicals that help transmit signals between neurons or brain cells. In people with Fragile X syndrome, the gene that makes a protein needed for the brain cells to communicate with each other is not working properly. Without this protein, the communication between the neurons weakens.
The study "Changes in Sensitivity of Reward and Motor Behavior to Dopaminergic, Glutamatergic, and Cholinergic Drugs in a Mouse Model of Fragile X Syndrome" is published in the online journal PLoS One.