The discovery raises the possibility of helping victims of post-traumatic stress disorder by freeing them of their demons.
However, currently in the UK, electroconvulsive therapy (ECT) is only reserved for certain forms of mental illness, including severe depression and mania.
ECT triggers a brief epileptic fit by delivering a jolt of electricity to the brain via electrodes placed on the head.
In the new study, researchers tested its effect on memory on 39 patients already receiving ECT for depression.
Participants were told two emotionally unpleasant stories presented in the form of a slideshow accompanied by a voice over. A week later story memories were "cued" by showing the first slide partially covered.
Immediately afterwards, one group of patients were given ECT.
A day later, patients were tested on what they could recall about events relating to the first slide. Those who had undergone ECT struggled, while the memories of patients who had not received the therapy were unaltered.
Only those memories that were reactivated by the cue were disrupted by ECT, according to the findings reported in the journal Nature Neuroscience.
Commenting on the results, Dr Aidan Horner, from the University College London Institute of Cognitive Neuroscience, said: "The ability to disrupt or even abolish specific memories, whilst leaving others intact, could have important therapeutic applications. For example, selectively disrupting memories in patients with conditions such as post-traumatic stress disorder."