Recurrent involuntary autobiographical memories: characteristics and links to mental health status

Neural signatures of default mode network subsystems in first-episode, drug-naive patients with major depressive disorder after 6-week thought induction psychotherapy treatment

Evidence indicates that the default mode network (DMN) plays a crucial role in the neuropathology of major depressive disorder (MDD). However, the neural signatures of DMN subsystems in MDD after low resistance Thought Induction Psychotherapy (TIP) remain incompletely understood. We collected functional magnetic resonance imaging data from 20 first-episode, drug-naive MDD and 20 healthy controls (HCs). The DMN was segmented into three subsystems and seed-based functional connectivity (FC) was computed. After 6-week treatment, the significantly reduced FCs with the medial temporal lobe memory subsystem in MDD at baseline were enhanced and were comparable to that in HCs. Changed Hamilton Depression Rating Scale scores were significantly related with changed FC between the posterior cingulate cortex (PCC) and the right precuneus (PCUN). Further, changed serotonin 5-hydroxytryptamine levels were significantly correlated with changed FCs between the PCC and the left PCUN, between the posterior inferior parietal lobule and the left inferior temporal gyrus, and between the retrosplenial cortex and the right inferior frontal gyrus, opercular part. Finally, the support vector machine obtained an accuracy of 67.5% to distinguish between MDD at baseline and HCs. These findings may deepen our understanding of the neural basis of the effects of TIP on DMN subsystems in MDD.

Recurrent involuntary memories and mind wandering are related but distinct

Spontaneous thought is common in daily life, and includes recurrent involuntary autobiographical memories (IAMs; memories retrieved unintentionally and repetitively) and mind wandering (MW). Both recurrent IAMs and MW are often unintentional or unconstrained, and both predict symptoms of mental health disorders. However, not all MW is unintentional, and not all IAMs are unconstrained. To what extent do recurrent IAMs and MW converge versus diverge? Undergraduates (N = 2,701) completed self-report measures of recurrent IAMs, trait MW, and psychopathology (i.e., PTSD, depression, anxiety). Regressions indicated that recurrent IAMs were significantly associated with spontaneous MW, but not deliberate MW. Further, both spontaneous MW and recurrent IAMs had unique relationships with disorder symptoms. Results suggest that recurrent IAMs are related to MW to the extent that recurrent IAMs are spontaneous. Conversely, recurrent IAMs are distinct from MW to the extent that recurrent IAMs' associations with disorder symptoms could not be solely explained by trait MW (and vice versa). This work highlights related, but distinguishable, forms of spontaneous thought and their transdiagnostic links with psychopathology.

Specific topics, specific symptoms: linking the content of recurrent involuntary memories to mental health using computational text analysis

Researchers debate whether recurrent involuntary autobiographical memories (IAMs; memories of one's personal past retrieved unintentionally and repetitively) are pathological or ordinary. While some argue that these memories contribute to clinical disorders, recurrent IAMs are also common in everyday life. Here, we examined how the content of recurrent IAMs might distinguish between those that are maladaptive (related to worse mental health) versus benign (unrelated to mental health). Over two years, 6187 undergraduates completed online surveys about recurrent IAMs; those who experienced recurrent IAMs within the past year were asked to describe their memories, resulting in 3624 text descriptions. Using a previously validated computational approach (structural topic modeling), we identified coherent topics (e.g., "Conversations", "Experiences with family members") in recurrent IAMs. Specific topics (e.g., "Negative past relationships", "Abuse and trauma") were uniquely related to symptoms of mental health disorders (e.g., depression, PTSD), above and beyond the self-reported valence of these memories. Importantly, we also found that content in recurrent IAMs was distinct across symptom types (e.g., "Communication and miscommunication" was related to social anxiety, but not symptoms of other disorders), suggesting that while negative recurrent IAMs are transdiagnostic, their content remains unique across different types of mental health concerns. Our work shows that topics in recurrent IAMs-and their links to mental health-are identifiable, distinguishable, and quantifiable.

Emotional autobiographical memory retrieval in time domain

Autobiographical memory (AM) is an important psychological phenomenon that has significance for self-development and mental health. The psychological mechanisms of emotional AM retrieval and their association with individual emotional symptoms remain largely unclear in the literature. For this purpose, the current study provided cue words to elicit emotional AMs. Event-related potentials (ERPs) associated with the retrieval process of AMs were recorded and analyzed. We found that the ERP component N400 was sensitive to both emotional valence and retrieval state, such that its amplitude was larger for negative compared to positive AMs, and larger responses for unrecalled compared to recalled AMs. Further, the N400 amplitude in the positive recalled condition was correlated with individual difference in depression (measured by the Beck Depression Inventory). Another ERP component, the late positive potential (LPP), was also sensitive to emotional valence, such that its amplitude was larger (i.e., more positive-going) for positive compared to negative cues. No significant effect was observed on the early ERP components P1, N1, or P2. The current findings bring new understanding on the difference between positive and negative AMs retrieval in the time domain. Also, the importance of this difference to the individual level of depression is worth noting.

Understanding autobiographical memory content using computational text analysis

Although research on autobiographical memory (AM) continues to grow, there remain few methods to analyze AM content. Past approaches are typically manual, and prohibitively time- and labour-intensive. These methodological limitations are concerning because content may provide insights into the nature and functions of AM. In particular, analyzing content in recurrent involuntary autobiographical memories (IAMs; those that spring to mind unintentionally and repetitively) could resolve controversies about whether these memories typically involve mundane or distressing events. Here, we present computational methods that can analyze content in thousands of participants' AMs, without needing to hand-code each memory. A sample of 6,187 undergraduates completed surveys about recurrent IAMs, resulting in 3,624 text descriptions. Using frequency analyses, we identified common (e.g., "time", "friend") and distinctive words in recurrent IAMs (e.g., "argument" as distinctive to negative recurrent IAMs). Using structural topic modelling, we identified coherent topics (e.g., "Negative past relationships", "Conversations", "Experiences with family members") within recurrent IAMs and found that topic use significantly differed depending on the valence of these memories. Computational methods allowed us to analyze large quantities of AM content with enhanced granularity and reproducibility. We present the means to enable future research on AM content at an unprecedented scope and scale.

Narrative thinking lingers in spontaneous thought

Some experiences linger in mind, spontaneously returning to our thoughts for minutes after their conclusion. Other experiences fall out of mind immediately. It remains unclear why. We hypothesize that an input is more likely to persist in our thoughts when it has been deeply processed: when we have extracted its situational meaning rather than its physical properties or low-level semantics. Here, participants read sequences of words with different levels of coherence (word-, sentence-, or narrative-level). We probe participants’ spontaneous thoughts via free word association, before and after reading. By measuring lingering subjectively (via self-report) and objectively (via changes in free association content), we find that information lingers when it is coherent at the narrative level. Furthermore, and an individual’s feeling of transportation into reading material predicts lingering better than the material’s objective coherence. Thus, our thoughts in the present moment echo prior experiences that have been incorporated into deeper, narrative forms of thinking.

Some experiences linger in our minds, while others quickly fade. Here, the authors show that the extent to which our recent experiences linger into subsequent thought increases as a function of processing depth.

Emotional autobiographical memory impairment features in three mental disorders

We proposed the Emotional Autobiographical Memory Test (EAMT) as a specialized method for measuring emotional autobiographical memory impairment in patients with mental disorders. The EAMT was tested with 32 patients with schizophrenia, 18 patients with bipolar disorder, 32 patients with depression, and 42 people undiagnosed with such disorders. We extracted 13 indices of five kinds of features from participants' emotional autobiographical memory and compared them among the four groups. The overgeneralization result in the schizophrenia and depression groups was consistent with previous results, supporting the EAMT's validity. However, inconsistent with previous results, overgeneralization was not found in the bipolar disorder group. Further, the count of involuntary memories in the patient groups (vs. control group) was significantly smaller, which can guide future researchers in investigating the psychopathology of mental disorders.

Sense of purpose in life, cognitive function, and the phenomenology of autobiographical memory

There are individual differences in the phenomenological re-experiencing of autobiographical memories. We examine whether sense of purpose in life and cognitive function are associated with the phenomenology of a recent memory related to the coronavirus pandemic. Participants reported on their sense purpose and completed tasks that measured processing speed and visuospatial ability before the pandemic in January-February 2020 and subsequently retrieved and rated a memory related to the pandemic in July 2020 (N=796; Mage=58.05, SD=14.14, range 19-85). Participants with a greater sense of purpose reported memories that were more phenomenologically rich (e.g., more vivid, coherent, accessible), whereas cognitive function was primarily related to greater perceived accessibility of the memory but not to most other aspects of phenomenology. The pattern of associations was similar when accounting for depressive symptoms, and none of the associations was moderated by age. The present research suggests that individuals with a higher sense of purpose in life have autobiographical memories with richer phenomenology. To the extent that memories function to sustain well-being, social connections, and cognitive health, rich phenomenology may be one pathway through which purpose leads to these better outcomes.