There are currently no effective treatments for the core symptoms of autism spectrum disorder (ASD), such as social and communication difficulties. A new study uses a computer-based protein interaction network to identify whether existing drugs provide a new therapeutic approach. The researchers found that a common anti-diarrheal drug may have potential in treating the social problems associated with ASD.
Can you teach old medicine new tricks? Although drug treatments for the core symptoms of autism spectrum disorder (ASD) are not currently available, could a new treatment be offered even if existing medication has not been previously associated with ASD? That was the question posed by a new study in the journal. Frontiers in Pharmacology. The researchers used a computer model that included the proteins and interactions involved in ASD.
By looking at how different drugs affect the proteins in the system, they identify candidates for treating it. A commonly used antidiarrheal drug, loperamide, has shown great promise, and researchers have an intriguing hypothesis about how it might work to treat ASD symptoms. Some of the most common symptoms in ASD include problems with social interaction and communication.
“There are currently no drugs approved for the treatment of social communication disorders,” said Dr. Elise Koch of the University of Oslo. “However, most adults and about half of children and adolescents with ASD are treated with antipsychotic medications, which have serious side effects or are ineffective in ASD.”
Using drugs as a new treatment
Researchers have turned to medicine to find new ways to treat ASD, which involves using existing drugs to treat different conditions. The approach has many advantages, as there is often extensive knowledge about existing drugs in terms of their safety, side-effects and the biological molecules they interact with in the body.
To identify new treatments for ASD, the researchers used a computer-based protein interaction network. Such networks include proteins and the complex interactions between them. When studying biological systems, it is important to take this complexity into account, because affecting one protein can often have knock-on effects elsewhere.
The researchers constructed a protein interaction network that included ASD-related proteins. By examining existing drugs and their interactions with proteins in the network, the team identified several candidates that may target the biological process underlying ASD.
The most promising drug is called loperamide, which is commonly used for diarrhea. While it may seem strange that an anti-diarrheal drug can treat the main symptoms of ASD, the researchers hypothesized how it might work.
From an upset gastrointestinal system to ASD
Loperamide binds to and activates a protein called the μ-opioid receptor, which is commonly attacked by opioid drugs such as morphine. Along with the commonly expected effects of opioid drugs, such as pain relief, the μ-opioid receptor also influences social behavior.
In previous studies, genetically engineered mice lacking μ-opioid receptors exhibited social deficits similar to those seen in ASD. Interestingly, drugs that activate μ-opioid receptors helped to restore social behavior.
These results in mice suggest that loperamide or other drugs that target the μ-opioid receptor may represent a new way to treat social symptoms in ASD, but further work is needed to test this hypothesis. In any case, the current study shows the power of conjecture that old drugs can indeed learn new tricks.