Ketamine, an anesthetic, has been used off-label to treat depression since the 1990s. There are more than 500 ketamine infusion clinics in the U.S.
Researchers at Cleveland Clinic are investigating exactly how ketamine works on the brain through an imaging study. Brian Barnett, MD, clinical director of the Cleveland Clinic Psychiatric Treatment Resistance Program, told Becker’s most research in ketamine treatment has focused on unipolar depression. This particular study focuses on treatment-resistant bipolar depression.
Bipolar depression is less common, and often more difficult to treat, than unipolar depression, Dr. Barnett said.
Ketamine therapy may be slightly less effective in treating bipolar than unipolar depression, Dr. Barnett added, but still delivers results for a disease that can often be resistant to other medication.
In previous studies, around half of patients with treatment-resistant bipolar depression respond to ketamine, and see a 50% or more decrease in depression symptoms, he said.
“When you’re talking about treatment-resistant depression, there’s often a 10% or fewer chance that the next antidepressant or medication is going to work. So these are still pretty astounding results,” he said. “We want to gain a better understanding of how ketamine is doing this.”
The study will use a 7-Tesla MRI to study patients’ brain activity before and after they receive ketamine infusions. The specialized MRI machine provides more detailed images than a typical MRI, Steven Jones, MD, PhD, vice chair of research and academic affairs at the Cleveland Clinic Neuroradiology Institute told Becker’s.
The detailed imaging the 7 Tesla MRI provides makes it easier to see the blood oxygenation level dependent — or BOLD — effect in the brain, Dr. Jones said. Small changes in brain blood flow can reveal networks, he said.
“We’re looking for the networks — places in the brain that are functionally connected,” he said. “We want to find out is, do these networks get changed with the introduction of ketamine? And moreover, does change due to ketamine vary if you’re a responder or a nonresponder?”
Ketamine treatment tends to work very quickly, Dr. Barnett said. Individuals often have an improvement in symptoms by the next day.
“In the long run, within psychiatry, we’d love to be able to reverse-engineer ketamine as a treatment. It is involved logistically, and there are some challenges with using it,” he said. “Eventually, we’d like to design other treatments that work the same way, without the same logistical barriers.”
Ketamine is prescribed off-label to treat depression, meaning most insurers do not pay for treatment, Dr. Barnett said. While the drug itself is cheap, individuals have to receive the drug in an infusion center, which can cost between $500 and $2,000 a treatment, meaning the treatment is only available to patients with the means to pay for it.
Patients in the Cleveland Clinic study will be able to receive up to nine ketamine infusions at no cost, Dr. Barnett said. The study is open label, so no participants will receive placebos.
Though ketamine treatment often drives headlines, not every psychiatrist will refer patients to the treatment, Dr. Barnett said, over concerns about the addictive potentials of the drug.
The study will allow researchers to get a better understanding of ketamine’s safety in bipolar depression, Dr. Barnett said.
“Ultimately, we hope the results will show this is a safe and effective treatment for bipolar depression, and encourage providers to refer patients for that treatment if they’re able to pay for it,” he said.
