A research group led by Professor Yuko Hakamata from the Faculty of Medicine at the University of Toyama, Professor Hirokuni Tagaya from the Kitasato University School of Allied Health Sciences, and Director Hiroaki Hori from the National Institute of Mental Health at the National Center of Neurology and Psychiatry, in collaboration with the National Institute of Occupational Safety and Health, Japan, Kanazawa University, and Kyoto University, announced the development of a memory intervention program to alleviate "memory bias," the brain's tendency to recall only negative events. The researchers developed a cognitive intervention program called "CBM-M" to reduce memory bias. The program's intervention was confirmed to reduce the secretion of cortisol, a stress hormone. This is expected to contribute to the prevention and treatment of stress-related mental disorders. The results were published in Psychological Medicine.
Compared with sham training, CBM-M specifically lowered cortisol levels and stress vulnerability, whose magnitudes were correlated with reduced negative memory bias. Brain scans showed it also strengthened connectivity between the amygdala and the anteromedial orbitofrontal cortex, suggesting a neural mechanism for its benefits. CC BY-NC-ND 4.0
Provided by Professor Yuko Hakamata from the University of Toyama, Japan
In modern society, mental disorders related to stress, including depression, are believed to be increasing both domestically and internationally, with one-fifth of the general population said to experience them at least once in their lifetime. The onset and exacerbation of these mental disorders are closely associated with information processing biases (cognitive biases), such as focusing only on the negative aspects of things while disregarding the positive aspects. However, the development of psychological intervention programs to alleviate cognitive biases has made little progress.
Therefore, the research group developed CBM-M, a program designed to alleviate memory bias. They verified its effectiveness and investigated the neural mechanisms of action.
A parallel-group randomized controlled trial was conducted on 58 adults at risk of developing depression or anxiety disorders. Twenty-nine participants were randomly assigned to either the CBM-M group or to a sham training group. The participants completed eight online sessions (approximately 10 minutes each) of the program over one month.
CBM-M was developed based on word recall and completion tasks. The CBM-M group's tasks involved memorizing both positive and negative words while simultaneously completing a module to facilitate the recall of positive memories. In contrast, the sham training group's tasks involved memorizing both positive and negative words but did not include the positive memory retrieval facilitation module.
Before and after the intervention, anxiety and depressive traits, anxiety and depressive symptoms, implicit and explicit memory biases, and the degree of autobiographical memory specificity were measured. In addition, intrinsic functional connectivity was measured using functional magnetic resonance imaging (fMRI) and basal cortisol secretion levels (saliva collected at 10 time points over two consecutive days) were assayed before and after the intervention.
As a result, both groups showed reductions in depressive and anxiety traits and symptoms. However, compared with the sham training group, the CBM-M group showed significantly greater reductions in "stress vulnerability," a subscale of anxiety and depression-related traits; self-related explicit memory bias; and daytime cortisol secretion levels (which increase under stress). Furthermore, the magnitude of memory bias reduction was correlated with the magnitude of stress vulnerability and cortisol secretion reduction. It was also confirmed that functional connectivity between the right amygdala and medial orbitofrontal cortex (mOFC) increased more from before to after the intervention in the CBM-M group than in the sham training group.
Stress vulnerability refers to susceptibility to the effects of stress, and memory bias refers to the tendency to remember and recall negative information more than other information. Implementation of the program alleviated memory bias and enhanced resilience to stress.
The researchers also found that CBM-M demonstrated its effectiveness in strengthening the connectivity between the amygdala, which is involved in memory recall, and the mOFC
Hakamata commented: "We do not normally question our memories of events we have experienced. However, our brains can unconsciously distort reality in a negative direction and make us believe it to be true. These automated information processing patterns (in other words, habits) that occur in the brain can cause serious anxiety and depression and be a factor in prolonging them. This research led us to new discoveries as we attempted to develop methods to directly alleviate the brain's habits, which have not been addressed in conventional treatments. Based on these findings, we aim to refine and develop future research to establish methods that can be widely delivered to clinical practice and society."
Journal Information
Publication: Psychological Medicine
Title: The effectiveness and neurobiological actions of memory bias modification: a randomized controlled trial
DOI: 10.1017/S0033291725102535
This article has been translated by JST with permission from The Science News Ltd. (https://sci-news.co.jp/). Unauthorized reproduction of the article and photographs is prohibited.