Throughout human history, many unfortunate individuals have fallen victim to crippling phobias, from natural fears such as arachnophobia, to fears acquired from traumatic events, leading to PTSD. These conditions can take sometimes years, even lifetimes to cure, and some individuals never truly overcome their phobias. However, a new therapy that re-writes the memories associated with these fears can cure an individual of their phobia — in roughly two minutes.

A recent experiment conducted at the University of Amsterdam involved fifteen individuals, each suffering from arachnophobia. The subjects were administered a drug called propranolol, while being instructed to contemplate touching a spider, something they wouldn’t ordinarily be able to force themselves do. In all 15 cases, the subjects were able to successfully, and more confidently, touch a live tarantula. The effect also did not diminish, with the subjects still being able to approach spiders a year after their treatment.

“They couldn’t believe it,” remarked psychologist Merel Kindt, who co-authored the study. “They went on and on. One even asked if they could have it in their hand.”

The theory behind what is happening is that the process of “memory reconsolidation”, the strengthening of one’s synapses during the recall of a memory, are being interrupted, allowing a new memory to overwrite it. When the brain forms a new memory, our synapses, the spaces between the individual neurons, write themselves, chemically recording a pattern that corresponds to the new memory. When the memory is recalled, it is consolidated, in that it is made permanent, forming a long-term memory. And until recently, scientists assumed that these permanent pathways couldn’t be re-written.

This changed in 1999, when neuroscientist Karim Nader ran an experiment on lab mice: he first conditioned them to associate a high-pitched beep with an electric shock, so that whenever the beep sounded alone, the mice would still react with fear, anticipating the electric shock. He then administered anisomycin to the mice, while replaying the same beep. While typically used as an antibiotic, anisomycin is also known to be a protein-synthesis inhibitor, preventing the formation of long-term memories. Following the treatment, the mice began to disregard the beep, indicating that their fear of it was gone.

This prompted the theory that long-term memories actually need to be re-written each time they are accessed, instead of being the permanent recordings that they were assumed to be. This enables these memories to be re-written as they are being accessed, using a compound like propranolol, to interrupt their reconsolidation. While the subjects in the arachnophobia study wouldn’t forget what they knew about spiders — a complex set of patterns that would still be reinforced — the memory associated with the fear associated with spiders would be interrupted during the procedure, replacing it with the memory of a positive experience with the arachnids.

There are still a number of hurdles to overcome before this new concept becomes an accepted form of therapy: while exposing a patient to a spider in a clinical setting is easy, some conditions are much harder to address, such as the PTSD that a combat veteran might suffer. There are also concerns regarding the effectiveness it will have across different types of fear. Regardless, Kindt and her colleagues have high hopes for the development of this form of therapy: "Here we show for the first time that an amnesic drug given in conjunction with memory reactivation transformed avoidance behavior to approach behavior in people with a real-life spider fear. The new treatment is more like surgery than therapy."