Psychological therapy for psychogenic amnesia: Successful treatment in a single case study

What are the neural correlates of dissociative amnesia? A systematic review of the functional neuroimaging literature

AIM

Dissociative amnesia is an emblematic psychiatric condition in which patients experience massive memory loss ranging from focal to global amnesia. This condition remains poorly understood and this review aims to investigate the neuroanatomical feature of this disease.

METHODS

We conducted a systematic review of the scientific literature available on PubMed, up to December 1, 2022, using a combination of keywords referring to dissociative amnesia. We included every scientific report involving patients undergoing a functional imaging procedure.

RESULTS

Twenty-two studies met our inclusion criteria (gathering 49 patients). Only one was a controlled study with a large sample. The other 21 were case reports and case series. In resting state, neuroimaging studies mostly showed a hypo-activated right inferolateral prefrontal cortex, associated with limbic hypoactivity and lesser activation of the hippocampal and para-hippocampal structures. The patients also presented abnormal patterns of cerebral activation when performing memory tasks. When testing recognition of memories from the amnestic period, patients showed increased activation across temporal areas (hippocampal and para-hippocampal gyri) and the limbic network. When trying to recollect memories from an amnestic period compared to a non-amnestic period, patients failed to activate these structures efficiently. Most of these patterns tended to return to normal when symptoms resolved.

CONCLUSION

This review identified a paucity of controlled studies in the field of dissociative amnesia neuroimaging, which restricts the extrapolation of results. Patients with dissociative amnesia present a broad prefronto-temporo-limbic network dysfunction. Some of the brain areas implicated in this network might represent potential targets for innovative treatments.

The measurement of participant-reported memory across diverse populations and settings: a systematic review and meta-analysis of the Multifactorial Memory Questionnaire

The Multifactorial Memory Questionnaire (MMQ) is a participant-reported measure of memory satisfaction, ability, and strategy use. Initially validated with healthy older adults, it has since been used in many different populations and settings for a variety of purposes. We conducted a systematic review and meta-analysis of the measurement properties of the MMQ across multiple, diverse studies.

METHODS

The study was designed using the Consensus-Based Standards for the Selection of Health Measurement Instruments and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We calculated aggregate statistics and evaluated the methodological quality of 29 studies retrieved from PsycINFO, MEDLINE, EMBASE, and Web of Science.

RESULTS

Analyses revealed high-quality evidence for internal consistency, stability, measurement error, convergent validity, and known-groups validity of the three MMQ scales. There was moderate-quality evidence for responsiveness and structural validity, with some studies identifying separate factors for internal and external memory strategy use. Measurement properties were similar across languages, participant samples, and study designs.

CONCLUSIONS

The MMQ is a valid, reliable, and responsive measure across diverse settings and populations. Future research is needed to determine whether more detailed information can be obtained from the scales, specifically, internal versus external strategy use.

State-Dependent Memory: Neurobiological Advances and Prospects for Translation to Dissociative Amnesia

In susceptible individuals, overwhelming traumatic stress often results in severe abnormalities of memory processing, manifested either as the uncontrollable emergence of memories (flashbacks) or as an inability to remember events (dissociative amnesia, DA) that are usually, but not necessarily, related to the stressful experience. These memory abnormalities are often the source of debilitating psychopathologies such as anxiety, depression and social dysfunction. The question of why memory for some traumatic experiences is compromised while other comparably traumatic experiences are remembered perfectly well, both within and across individuals, has puzzled clinicians for decades. In this article, we present clinical, cognitive, and neurobiological perspectives on memory research relevant to DA. In particular, we examine the role of state dependent memory (wherein memories are difficult to recall unless the conditions at encoding and recall are similar), and discuss how advances in the neurobiology of state-dependent memory (SDM) gleaned from animal studies might be translated to humans.