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Letter to the Editor: Simply avoiding reactivating fear memory after exposure therapy may help to consolidate fear extinction memory

Published online by Cambridge University Press:  10 July 2014

R. Dardennes*
Affiliation:
Faculty of Medicine, University Paris Descartes, Paris, France
N. Alanbar
Affiliation:
Centre of Psychiatry and Neurosciences, Sainte-Anne Hospital, Paris, France
A. Docteur
Affiliation:
Hospital Sainte-Anne, Paris, France
S. M. Divac
Affiliation:
Hospital Sainte-Anne, Paris, France
C. Mirabel-Sarron
Affiliation:
Hospital Sainte-Anne, Paris, France
*
Address for correspondence: Prof. R. Dardennes, CMME, 100 rue de la Santé, 75674 Paris Cedex 14, France. (Email: r.dardennes@ch-sainte-anne.fr)
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Abstract

Type
Correspondence
Copyright
Copyright © Cambridge University Press 2014 

Enhancing the efficiency of psychotherapy has become a central issue in its recent development as cost-effective approaches and many studies have shown that it is indeed possible to increase the efficacy of psychological treatment. In the recent study of Kleim et al. (Reference Kleim, Wilhelm, Temp, Margraf, Wiederhold and Rasch2014), going to sleep immediately after exposure increased the efficacy of the treatment of spider phobia, compared to staying awake after a session. The authors explain this effect by the benefits of sleep on memory consolidation found in earlier studies. Therefore, if exposure is followed by sleep, the spider non-fearful memories will be better reactivated when competing with spider fearful memories.

Kleim et al. (Reference Kleim, Wilhelm, Temp, Margraf, Wiederhold and Rasch2014) used a 90 min-long documentary about European cities for the awake condition. We can assume that this documentary contains some cues associated with spiders, as spiders can be found in most modern homes. Thus, this experiment may have compared a post-exposure period devoid of spider cues, that is a 90-min sleep period where less than 20% of recorded sleep gave the opportunity to dream and have nightmares about spiders, to a post-exposure period that may have contained spider fear-associated cues. These cues could reactivate spider fear memories and thus impair memory consolidation of non-fearful spider memories.

It is considered that fearful memories consolidate progressively into persistent traces through synthesis of new proteins (McGaugh, Reference McGaugh2000). When retrieval of a consolidated fear memory occurs, this memory returns transiently to a labile state, thus requiring a new protein synthesis to persist further (Nader et al. Reference Nader, Schafe and Le Doux2000). This unstable period, called a consolidation window, lasts a few hours. Exposure therapy is based on the experimental fear extinction model that helps to develop new, non-fearful memories that follow the same consolidation process. During this labile state, the memory is amenable to enhancement or disruption (Nader et al. Reference Nader, Schafe and Le Doux2000). Monfils et al. (Reference Monfils, Cowansage, Klann and LeDoux2009) elegantly demonstrated that when fear extinction training occurs within the consolidation window of a learned fear (i.e. within 6 h after triggering fear), fear memory is disrupted and later permanently attenuated. We can deduce, therefore, that it is important for phobic subjects to avoid reactivating fear memories during the consolidation period of non-fear memories.

The study of Kleim et al. (Reference Kleim, Wilhelm, Temp, Margraf, Wiederhold and Rasch2014) emphasizes that, to ensure that the next 6 h needed for memory consolidation will not be disturbed by exposure to phobic cues (and reactivate the fear), behaviour therapists must enquire about post-exposure session activities of treated patients.

We need further studies assessing the specific positive effects of sleep, in the post-exposure period, compared to the vigilant state in a phobic cue-free environment, to determine whether it might be considered a necessary condition for better consolidation of non-fear memories.

Declaration of Interest

None.

References

Kleim, B, Wilhelm, FH, Temp, L, Margraf, J, Wiederhold, BK, Rasch, B (2014). Sleep enhances exposure therapy. Psychological Medicine 44, 15111519.Google Scholar
McGaugh, JL (2000). Memory – a century of consolidation. Science 287, 248251.Google Scholar
Monfils, MH, Cowansage, KK, Klann, E, LeDoux, JE (2009). Extinction-reconsolidation boundaries: key to persistent attenuation of fear memories. Science 324, 951955.Google Scholar
Nader, K, Schafe, GE, Le Doux, JE (2000). Fear memories require protein synthesis in the amygdala for reconsolidation after retrieval. Nature 406, 722726.Google Scholar