Posttraumatic stress disorder (PTSD) is a psychological condition that can develop following exposure to traumatic events, characterized by intrusive thoughts and re-experiencing symptoms, avoidance of trauma reminders, negative cognitions and mood, and heightened arousal [1]. A proposed mechanism underlying the development and maintenance of PTSD is disruptions in the encoding, consolidation, and retrieval of negatively- and positively-valenced autobiographical memories [2-4]. Evidence suggests that survivors of trauma with PTSD report difficulties accessing and detailing positive autobiographical memories [5-7], akin to reported difficulties with traumatic autobiographical memories [8]. Unsurprisingly, PTSD interventions typically target the content, processes, and phenomenological characteristics of autobiographical memories [9,10]. While such trauma-focused interventions (eg, prolonged exposure and cognitive processing therapy) are effective for many survivors of trauma, a significant proportion of survivors of trauma do not respond to these treatments, and there is a high degree of dropout from these interventions [11]. This highlights the need to develop alternative therapeutic approaches.

While most PTSD interventions address engagement with only traumatic autobiographical memories, only a few other interventions address both traumatic and positive autobiographical memories or only positive autobiographical memories and have been shown to be effective. For instance, Memory Specificity Training (targeting one’s ability to retrieve specific autobiographical memories irrespective of valence) is effective for PTSD and posttrauma distress [12,13]. Also, Broad-Minded Affective Coping, a positive emotion induction technique through the retrieval of positive autobiographical memories, improves mood among individuals with PTSD [14]. Such evidence suggests that a focus on positive autobiographical memories may be a helpful target in PTSD interventions.

The PTSD-Positive Memory Model [15,16] outlines that when survivors of trauma repeatedly retrieve, relive, and detail specific positive autobiographical memories, they may experience an improvement in PTSD symptoms, affect, and beliefs over time [15]. This model was foundational to the development of the Processing of Positive Memories Technique (PPMT), which is a 4- to 5-session intervention tailored to PTSD symptoms. During PPMT sessions, survivors of trauma are guided to narrate details of salient positive autobiographical memories; to access and strengthen positive values, affect, strengths, and thoughts associated with these memories; and to engage in positive affective, cognitive, and behavioral changes [17]. PPMT is influenced by positive psychology, a field that emphasizes factors and mechanisms that enhance psychological well-being rather than focusing solely on pathology [18,19]. PPMT draws from positive psychology interventions (eg, sharing positive narratives with others and using mental imagery to re-expereince positive events) [19-21] and from interventions that increase memory retrieval to improve mental health [22]. The detailed session-by-session content of PPMT is outlined by Contractor and colleagues [17].

Practicing PPMT may help survivors of trauma retrieve more positive autobiographical memories over time, which may also translate to retrieving fewer negative autobiographical memories. Consequently, survivors of trauma may be able to better contextualize and integrate traumatic autobiographical memories with existing beliefs [23] and with other memories [2,24], which in turn could aid recovery after a trauma [2,25]. Positive autobiographical memories may also become primary reference points to interpret experiences and influence self-concept [26-28]. Furthermore, by repeatedly retrieving positive autobiographical memories and associated content, survivors of trauma may lessen their focus on negative material, experience more positive affect, and downregulate negative affect [29-32]. This may be especially helpful for survivors of trauma who experience emotional distress from retrieving negative autobiographical memories. In turn, this improved affect may help survivors of trauma positively interpret events [29,33] and note more positive content in their thoughts [34]. Overall, retrieving positive autobiographical memories may improve well-being [35], resilience [36], and adaptive coping [37], serving as a reminder that there are positive values and thoughts to hold on to despite the hardships faced by survivors of trauma.

Pilot studies have shown that PPMT is feasible and may improve therapeutic outcomes for survivors of trauma. Using an experimental design, a 2-session modified-PPMT [38] and a 5-session PPMT protocol [39] were compared to a neutral memory condition among survivors of trauma. In the first study, authors found that participants who repeatedly narrated the content of positive autobiographical memories reported decreases in PTSD symptom severity and negative affect, as well as increases in positive affect across time compared to the control condition [38]. In the second study, authors found that survivors of trauma who repeatedly retrieved positive (and neutral) memories reported less PTSD and depression severity, fewer posttrauma cognitions, and improved affect [39]. Using an open-label pilot trial, the feasibility and effects of the 5-session PPMT were examined among 12 survivors of trauma [40,41]. The authors found that PPMT reduced PTSD symptoms, reduced negative affect, and improved regulation of positive affect, and there were good feasibility indicators for PPMT (eg, PPMT was acceptable).

Critically, no study has examined PPMT’s effects using a larger community sample, nor has there been any exploration of whether PPMT is associated with postintervention changes in how survivors of trauma react to events in daily life. We can hypothesize that PPMT may impact individuals’ daily-life affect and cognitions; these impacts represent hypothesized mechanisms through which PPMT may reduce PTSD symptom severity over time. Most studies examining PTSD intervention impacts use case-series designs, in which data are collected from a group of individuals pre- and postintervention and an aggregate assessment of symptomatology pre- and postintervention is conducted and compared. However, this approach has some noteworthy limitations. Affect, cognitions, and PTSD symptoms are dynamic and vary daily in response to trauma reminders and experiences [42-44]; thus, evaluating intervention effectiveness using 2 snapshot assessments of symptomatology is not sufficiently reliable or nuanced. Furthermore, case-series designs do not examine the daily-level mechanisms of change for an intervention. Given that PPMT may impact daily life affect, cognitions, and symptoms, it is crucial that the data enable an examination of these constructs at the daily level.

These limitations can be overcome by integrating case-series designs with a daily diary framework for the pre- and post-PPMT assessments. Daily diary studies are an intensive longitudinal data collection method in which participants provide daily reports of their experiences each day over a period of time. Compared to retrospective assessments, daily diary data are considered more ecologically valid as they are collected in an individual’s everyday life rather than in a laboratory, more accurate and robust, and less vulnerable to recall bias [45]. Thus, the proposed study outlines information on the protocol of an ongoing study that combines case-series design and daily diary approaches to provide novel insights into PPMT’s effects on daily-level cognitive and affective experiences. This approach can be conceptualized as a special subtype of case-series design that enables an examination of within-person changes at the daily level.

Specifically, the proposed study aims to use daily diary data pre- and post-PPMT to examine changes in daily PTSD, daily affect, and daily cognitions. We hypothesize that at the daily level, participants will report (1) a lower count of endorsed daily PTSD symptoms pre- to post-PPMT, (2) increases in daily positive affect and decreases in daily negative affect pre- to post-PPMT, (3) increases in positive affect reactivity to daily positive events (a within-person index of linear relations between daily positive events and daily positive affect) pre- to post-PPMT, and (4) decreases in daily posttrauma cognitions pre- to post-PPMT. The aim of this study is to detail the proposed research protocol and our hypotheses regarding daily PTSD, daily negative affect, and daily cognitions pre- and post-PPMT. As a supplementary analysis, we will examine if participants report a greater count of retrieved specific positive memories pre- to post-PPMT.

Year 1 of the study (October 2021-September 2022) was primarily devoted to recruiting and training research personnel, obtaining ethics approvals, and preparing to launch the study. Year 2 of the study (October 2022-September 2023) has been focused on participant recruitment and data collection. During Year 3 of the study (October 2023-September 2024), we will complete data collection from our targeted sample and start the data cleaning and analysis process. During Year 4 of the study (October 2024-October 2025), we will complete the data analyses and prepare planned scientific outputs (eg, publications and presentations).

Data collection was initiated in March 2022. As of November 28, 2023, a total of 515 participants had consented to the study in the screening phase. Of those, 258 (50.1%) participants were eligible, 92 (35.7%) of which gave their consent by phone and attempted the first daily survey of the study. Of the 92 participants who completed the first daily survey, a total of 58 (63%) participants completed all intervention sessions and ≥13 daily surveys (≥60% of the daily surveys), and 28 (30.4%) participants dropped out in various stages of the study, mostly before the PPMT intervention. As of November 29, 2023, a total of 6 (6.5%) participants are currently participating in various phases of the study. Data collection is expected to end by June 2024. No analyses will be conducted until data collection has been completed.

This study aims to examine the daily-level impacts of PPMT, a promising adjunct or alternative to traditional PTSD treatments, in a trauma-exposed, nonclinical community sample. This study combines a case-series design and a daily diary design to examine potential mechanisms of change in PTSD symptoms by assessing daily affect, daily cognitions, and daily PTSD symptoms before and after the PPMT intervention. This approach enables a more nuanced and ecologically valid exploration of changes as compared with retrospective aggregate assessments. We outline the research protocol for this study, including the hypotheses and the proposed analyses. When data collection has been completed (estimated date: June 2024), we will test our hypotheses that, at the daily level, in comparison to their own pre-PPMT levels, following the PPMT intervention, participants will report (1) a lower count of endorsed daily PTSD symptoms, (2) increases in daily positive affect and decreases in daily negative affect, (3) increases in positive affect reactivity to daily positive events, and (4) decreases in daily posttrauma cognitions.

The findings of this proposed study could have significant implications. Results could clarify whether deficits in positive autobiographical memory processes (eg, retrieval and encoding) may also characterize PTSD alongside deficits in traumatic memory processes [7]. If the study’s hypotheses are confirmed, PPMT could be an additional therapeutic tool for clinicians to help clients with posttraumatic distress. Unlike other trauma interventions, PPMT exclusively targets positive autobiographical memories in treatment while redirecting attention away from negative content embedded in the positive memories. By uniquely combining positive and symptom-focused techniques and theories, PPMT aims to increase positive elements (eg, values, affect, and thoughts) while simultaneously decreasing PTSD severity [17].

There are some limitations to this study that should be considered. The study uses a self-report approach, which, although it reduces recall bias, is still subject to potential difficulties in the recall of experiences over the course of each day. Relatedly, while it reduces participant burden, the PC-PTSD measure is a PTSD symptom screener and usually is coupled with a comprehensive structured diagnostic interview for PTSD or a self-report measure assessing all 20 PTSD symptoms (which we do not do in this study due to the daily-level methodology and associated participant and time burdens). Furthermore, we are not gathering information on trauma characteristics such as the ages at which the trauma was experienced, the frequency or chronicity of each experienced trauma, or the time since the trauma has elapsed. Such information can impact posttrauma distress [78-80] and may moderate the impacts of PPMT in this study; hence, it should be empirically investigated in future research. In addition, while the research design of one assessment per day enables examination of changes in daily symptoms, affect, and cognition before and after the intervention, it does not have a sampling frequency nor sufficient power to examine fine-grained dynamic interactions between symptoms, affect, and cognition using even more complex modeling techniques. Lastly, our eligibility criterion permits individuals endorsing even 1 PTSD symptom at a clinical level to be included in the study. While such an approach accounts for impairment among individuals endorsing sub-threshold PTSD [81], it may also make it statistically difficult to detect any changes in PTSD symptoms (ie, the floor effect).

In conclusion, this study will contribute to the development of more personalized and alternative PTSD interventions for survivors of trauma who drop out or do not benefit from existing PTSD treatments. Further studies could examine PPMT as an ecological momentary intervention, wherein individuals receive daily reminders and instructions for engaging in therapy-relevant behaviors (eg, processing of positive memories). Such interventions can particularly benefit communities that do not have easy access to mental health services and are underserved in that regard [82]. Finally, this study will give insight into the mechanisms of change in the PPMT intervention through elucidating daily-level changes in affect, cognition, symptoms, and event reactivity.