Having won Wimbledon, Andy Murray is reputed to have been in a state of shock, without the ability to recall a single detail of his game. "He had no recollection whatsoever about that final game today. It was just a blur," Tim Henman, a tennis player who saw Murray in the locker room immediately after the game, told the BBC.

Some might say that what Murray experienced is a form of dissociative amnesia, where the continuity of memory is disrupted, such that important information and whole events may be forgotten due to trauma or severe stress. In cases of dissociative amnesia, formerly called "psychogenic" amnesia, the information that is lost is usually too extensive to be attributed to ordinary absentmindedness or forgetfulness related to aging. Unlike amnesia as its portrayed in movies, this form of amnesia pertains only to very specific events. Generally, dissociative amnesia is more common in women than in men and there may be a genetic component, or at least a suggestible element, since people reporting this disorder usually have close relatives who have had similar conditions. Although dissociative amnesia is considered uncommon, the fact is that remembering is even less common.

Forgetting, after all, is the common fate of most of our experiences.

Why Remember?

Scientists speculate that the purpose of memory is not to reminisce about the past, but to allow us to think, reason, and plan for the future. Episodic memory is the capacity to recall specific experiences and to reexperience individual events. With accumulating evidence to indicate that birds and rodents demonstrate similar cognitive ability, it is reasonable to assume that episodic memory offers significant advantages, some of which are common across species, others species-specific.

For instance, the ability to simulate plausible future events or scenarios is what allows humans to plan for the days ahead. In fact, episodic memory and episodic future thought are linked; the neural circuits involved in retrieving episodic memories and those involved in simulating future events overlap, suggesting the two capacities are intrinsically linked. Episodic memory, some researchers hypothesize, might also be useful for processing and using social information. Many aspects of group intelligence, such as family relationships, remain static, but others change over time (the tendency of someone to cooperate, say, or act aggressively) so interpretation of social action may depend on our capacity to remember specific experiences.

Emotional arousal enhances and encourages the storage of memories and so selectively creates enduring memories of our experiences. Emotion, then, by prioritizing our memories, establishes the importance and meaning of our lives. In fact, the neurobiological systems mediating emotional arousal and memory are closely linked. The adrenal stress hormones epinephrine and corticosterone released by emotional arousal regulate the consolidation of long-term memory while the amygdala plays a crucial role in mediating the influence of these stress hormones. In the amygdala, a release of norepinephrine and the activation of noradrenergic receptors are essential for stress hormone-induced memory enhancement. Both animal and human studies provide evidence that stress-induced activation of the amygdala as well as its interactions with other regions of the brain that are involved in processing memory play a role in ensuring that emotionally significant experiences are well-remembered.

Murray, in forgetting his Wimbledon game — which in all likelihood required an extraordinary amount of emotional as well as physical energy — may be unusual but his experience is not completely beyond the ordinary. Many people are unable to remember highly stressful events. In the case of those who do remember their experience of a major trauma, such as those who suffer from post-traumatic stress disorder (PTSD), some might rather forget like Murray.

Magic Pill

In various studies, propranolol, a beta-adrenergic blocker used for treating both cardiovascular disorders and anxiety disorders, shows promise in reducing subsequent memory for new emotional material in healthy adults. Propranolol has been examined in phases of memory: the phase of acquisition, formation, and encoding; the phase of emotional response and consolidation; and the phase of retrieval and reconsolidation. Having analyzed data from a variety of studies, researchers found that propranolol given before memory consolidation reduced subsequent recall for negatively-perceived stories, pictures, and word lists. Use of propranolol before reconsolidation also reduced subsequent recall for words with negative impact as well as the expression of cue-elicited fear responses.

Considering the pivotal role of harsh and powerful experiences in the development and persistence of mental disorders, interfering with the consolidation or reconsolidation of any memory naturally opens the door to new therapeutic approaches in psychiatry.

Many, though, argue against the use of propranolol as well as any other drug that could cause a deletion of memory. Fearful memories, after all, serve a protective purpose in that they remind you to avoid harmful situations. They play a role in the formation of our personalities and tastes, and inform our lives in other more subtle ways. The formation of memories is the formation of our sense of selves.

Others turn the ethical issue surrounding "forgetting drugs" on its head. The ethical issue is not about how the treatment might disrupt the sense of self of those who has undergone trauma and who may suffer from PTSD. Rather, the ethical issue is whether withholding a treatment for people suffering from PTSD, many who already have a disrupted sense of self and can no longer function in society because of it, can ever be justified.

Sources: Lonergan MH, Olivera-Figueroa LA, Pitman RK, Brunet A. Propranolol's effects on the consolidation and reconsolidation of long-term emotional memory in healthy participants: a meta-analysis. Journal of Psychiatry and Neuroscience. 2013.

Donovan E. Propranolol use in the prevention and treatment of posttraumatic stress disorder in military veterans: forgetting therapy revisited. Perspectives in Biology and Medicine. 2010.

Allen TA, Fortin NJ. The evolution of episodic memory. PNAS. 2013.