How Are New Medications for Autism Evaluated?

pillsThere are several drugs that are commonly prescribed to treat symptoms of autism, but there is no drug that treats the core deficits of the condition. Researchers face several challenges in the quest for that “miracle” drug, and the medications that are currently on the market don’t necessarily work for everyone.

The main difficulty lies in a lack of understanding the core biological cause of autism. Current research points to relatively rare genetic syndromes, copy number variants which duplicate or delete stretches of DNA, and spontaneous single-nucleotide mutations, which appear to increase the risk of autism in over 15 percent of children with the diagnosis. Since a single cause is yet to be discovered, it’s difficult to find a particular pharmaceutical that will address the core symptoms in the majority of cases.

There are two common approaches to testing new medications for autism. The first is to evaluate a treatment in a group of individuals with the diagnosis, while excluding those who suffer from a known genetic syndrome. Many of the medications that have been approved through this procedure target co-occurring symptoms of autism, rather than the core issues. This approach often results in a significant placebo effect, and doesn’t always explain why a particular drug is effective for some patients, but not others. Medications such as methylphenidate for hyperactivity in children, and fluoxetine for compulsive behaviors in adults were approved using this method.

The second approach is to target a specific sub-group of patients who suffer from a single defined genetic syndrome. These studies can be more specifically tailored to a particular biological effect, and the resulting treatment may be dramatic for a small sub-group of patients. However, these medications may not be as effective for the larger population of individuals on the spectrum.

Studies of mice with Fragile X syndrome found drugs that blocked a signaling receptor called mGlu5 promising, but the results on humans were mixed. Another clinical trial testing the effects of insulin-like growth factor 1 (IGF-1) on patients with Rett Syndrome is also underway.

Both of these syndromes account for less than 2 percent of individuals with autism, but researchers can target specific factors that are known to cause these disorders. Until scientists uncover the underlying biological cause of autism, these conditions are a good place to start targeted research of potential treatments, which may eventually be tested on a larger subgroup of patients with similar biological markers. This approach would be likely to find treatments that would help more patients. The difficulty lies in pinpointing the genetic markers that have the biggest effect on the symptoms of autism.

Clearly, autism is a complex condition that affects patients in various ways. It’s still unclear whether there is a single cause for autism, or whether many interlocking factors come into play to determine how the condition will manifest in a particular individual. For now, scientists are working to find treatments that will help as many patients as possible.