Can We Erase Painful Memories with Electroconvulsive Therapy?
by Xiaomeng Han
figures by Abigail Burrus
What comes to mind when you hear the term electroconvulsive therapy (ECT)? A cruel torture method for disobedient psychiatric patients portrayed in films like One Flew Over the Cuckoo’s Nest? Or a last-resort for treatment-resistant depression with less discomfort and fewer side-effects? New developments in using ECT to treat Post-Traumatic Stress Disorder might soon give us a new way to think about ECT: a tool to erase one’s painful memories, like the memory modification method in the film, Eternal Sunshine of the Spotless Mind.
Dealing with Painful Memories:The focus of PTSD treatment
Post-Traumatic Stress Disorder (PTSD) affects individuals who have gone through extremely frightening, painful, or stressful events in their life. A variety of situations can trigger PTSD symptoms: a war veteran can have flashbacks of fierce combat scenes, a terror attack victim can re-experience the horror of an explosion triggered by the sounds of firecrackers, and a victim of childhood abuse can have vivid nightmares well into adulthood. People who suffer from PTSD are haunted by their painful memories in a way that disturbs their daily functioning. The central focus of PTSD treatment has always been dealing with patients’ painful memories. Given its utility in many areas of psychiatry, ECT has been studied for its potential effects in modifying painful memories.
ECT is a medical procedure in which a brief, monitored seizure is generated in the patient’s brain by passing small electrical current through the brain while the patient is under general anesthesia. This treatment restores the chemical balance of the brain and is effective at alleviating the symptoms of a variety of mental illnesses, including severe depression, mania, and psychosis. Due to the fact that this treatment was given to patients without general anesthesia in its early days, ECT treatment has been stigmatized, particularly in the past several decades. However, nowadays, ECT actually is a safe, quick and effective procedure with few side effects and is used to achieve faster recovery in some patients with depression.
An Almost Forgotten ECT Study in Rats
When people first administered ECT to patients in the 1930s to 1950s, they found that it caused memory impairments. In retrospect, that might have been an early sign of the possible utility of ECT for treating PTSD.
Another early indicator of ECT as a potential treatment for PTSD came from a study of rats in the 1960s. A group of researchers at Rutgers University led by Dr. Donald J Lewis showed that ECT might be able to specifically erase fear memories. The researchers first made rats associate a tone with a fearful memory by playing this tone as they electrically shocked the rats’ feet. Then, when the researchers played the tone again, the rats froze in fear and licked their water bottle less due to their memory of being shocked upon hearing the tone.
Dr. Lewis and his team then tried using ECT to erase the rats’ memories of being shocked. To do this, they first reactivated the fearful memories in rats by playing the tone that the rats found frightening and then gave the rats ECT immediately afterwards. Surprisingly, they found that rats that were given ECT treatment licked their water bottle more when they heard the tone compared to control rats that were not given the treatment. This suggests that ECT impaired the fearful memory of being shocked.
Interestingly, the researchers found that in order for the ECT treatment to successfully impair the fearful memory, it had to be administered immediately after the researchers reactivated the memory by playing the tone that the rats found frightening. If Dr. Lewis’s team did not play the tone immediately before the ECT, the treatment had no effect on the rats. This suggests that ECT works by interfering with a memory as the rat is actively remembering it.
Rediscovering the Effect of ECT on Bad Memories
In 2014, nearly 50 years after the initial rat study, another group of researchers from Europe tested if ECT could help erase traumatic memories in patients with depression who were already undergoing ECT treatment. In their study, patients heard two traumatic stories involving violence or emotional pain through slide shows and narrative storytelling. One week later, only one story was “reactivated,” meaning the patients heard the traumatic story again. Immediately after the story was reactivated, patients received ECT treatment. The researchers then tested the patients’ memories of these two stories through multiple choices tests. As with the rats, the patients’ memories of the story that was “reactivated” immediately before ECT treatment were impaired. Impressively, they remembered the other story well, suggesting that ECT can be used to erase specific traumatic memories.
Possible Treatment Regimen for Erasing Painful Memories
Another 2014 study by group of psychiatrists from Germany showed that an ECT treatment regimen could be effective in ameliorating a PTSD patient’s symptoms. In this study, a single patient suffering from PTSD from a serious car accident and several episodes of sexual abuse underwent eight sessions of ECT. Before each ECT treatment, he was asked to describe one of his traumatic memories (the car accident), which is equivalent to “reactivating” that specific memory like playing the tone for those rats or re-hearing one of the traumatic stories by those depression patients. Right after his description, he was anesthetized and administered an ECT treatment. As the treatment progressed, the patient began to have fewer flashbacks and reduced anxiety and depression, indicating that his PTSD was improving. Incredibly, by the end of the treatment course, the patient could barely remember the car accident.
Moving into Clinical Trials? Explore Underlying Mechanisms? Or Be Cautious of Ethical Problems?
Based on these past studies, the use of ECT treatment to free PTSD patients from their devastating and painful memories seems promising. With inventions such as ultrabrief pulse width (a new method with minimal discomfort and side-effects), nowadays, ECT treatment is no longer as frightening as it used to be. Considering that knowledge and acceptance of ECT are growing in the general population, we can imagine that in the near future, there will be an increasing number of clinical trials with attempts to use ECT to treat people with PTSD. ECT is still not perfect. Scientists are still trying to improve and perfect memory reactivation techniques, treatment frequency, and length. However, as it stands, ECT is an incredibly promising choice for psychological treatment.
Moreover, these ECT studies may help neuroscientists understand how memories are formed in the brain. Based on several significant research papers also published around 2014, scientists now know that memories can be stored in certain neural cells or their connections. However, what happens to these cells and their connections during memory reactivation and ECT is still mysterious. One can only imagine how our memories are created, retrieved, and recreated in our mysterious brain.
Xiaomeng Han is a second year graduate student in the Harvard PhD Program in Neuroscience. She uses electron microscopy to study neuronal connectivity.
For more information:
- To grasp the basics of electroconvulsive therapy (ECT), check out this Scientific American article.
- For a more in-depth history of ECT, read this Scientific American article.
- The 1960s research on rats in the Science magazine can be found here. (http://science.sciencemag.org/content/160/3827/554.long)
- This National Institute of Mental Health page explores the definition, causes, symptoms and treatments of post-traumatic stress disorder (PTSD).
- For more on using ECT to erase painful memories in humans, check out this TIME article.