Subthreshold Posttraumatic Stress Disorder Symptoms Research Articles

Is inflammatory change associated with psychological risk and resilience in high-risk military personnel?

IntroductionIn military populations, the potential for under-reporting of Post-traumatic Stress Disorder (PTSD) symptoms and challenges in recognising early changes can make it difficult to detect an emerging disorder. However, early...

Examining the prevalence and health impairment associated with subthreshold PTSD symptoms (PTSS) among frontline healthcare workers during the COVID-19 pandemic

The COVID-19 pandemic has increased healthcare workers' (HCWs) risk for posttraumatic stress disorder (PTSD). Although subthreshold PTSD symptoms (PTSS) are common and increase vulnerability for health impairments, they have received little attention. We examined the prevalence of subthreshold PTSS and their relationship to physical health symptoms and sleep problems among HCWs during the pandemic's second wave (01/21–02/21). Participants (N = 852; 63.1% male; Mage = 38.34) completed the Short-Form PTSD Checklist (SF-PCL), the Cohen-Hoberman Inventory of Physical Symptoms, and the PROMIS Sleep-Related Impairment-Short-Form 4a. We created three groups with the SF-PCL: scores ≥11 = probable PTSD (5.5%); scores between 1 and 10 = subthreshold PTSS (55.3%); scores of 0 = no PTSS (39.2%). After controlling for demographics, occupational characteristics, and COVID-19 status, HCWs with subthreshold PTSS experienced greater physical health symptoms and sleep problems than HCWs with no PTSS. While HCWs with PTSD reported the greatest health impairment, HCWs with subthreshold PTSS reported 88% more physical health symptoms and 36% more sleep problems than HCWs with no PTSS. Subthreshold PTSS are common and increase risk for health impairment. Interventions addressing HCWs' mental health in response to the COVID-19 pandemic must include subthreshold PTSS to ensure their effectiveness.

Prevalence and Correlates of Anxiety, Depression, Perceived Stress, and Post-Traumatic Stress Symptoms in Parents with Adolescents in Residential Treatment

ABSTRACT Previous studies have suggested that parents with adolescents in residential treatment (RT) may struggle with their own mental health. However, few have comprehensively described parents’ mental health using valid and reliable measures and examined parent mental health in reference to other contextual factors that may be intertwined and intervenable. Therefore, the purpose of this exploratory study was to describe the perceived stress, symptoms of anxiety and depression, and post-traumatic stress disorder (PTSD) in parents with adolescents in RT in the United States. This cross-sectional study included a sample of parents (N = 71) with adolescents in RT. On average, parents reported elevated depressive symptoms, moderate stress, mild-to-moderate anxiety symptoms, and subthreshold PTSD symptoms. However, there were differences in mental health based on gender, race, ethnicity, adolescent living location, and adolescent psychiatric diagnoses (e.g., bipolar, depressive, and substance use disorders). Findings provide a more comprehensive description of parents’ mental health during the RT admission, underscoring the bidirectionality of parent-adolescent mental health and well-being. Practice Implications Parent mental health screening and treatment may be necessary because of elevated depressive symptoms, anxiety, and stress Parent stress is chronically elevated across the treatment trajectory, highlighting the need for parent preparation, support, and stress management Assessment of trauma and social support is needed because PTSD scores were higher in unpartnered parents Parent and adolescent mental health is bidirectional and providing treatment and support to parents benefits adolescents

The Phenomenology and Correlates of Flashbacks in Individuals With Posttraumatic Stress Symptoms

Reexperiencing symptoms are a hallmark of posttraumatic stress disorder (PTSD). Relatively little research has examined flashbacks in individuals with PTSD, and theoretical attempts to define and conceptualize flashbacks continue to be marked by considerable controversy. We compared individuals with PTSD or subthreshold PTSD symptoms (PTSS) with ( n = 45) and without flashbacks ( n = 32) to trauma-exposed controls ( n = 33) and control participants without trauma exposure ( n = 33). We compared the qualities of flashbacks of individuals with PTSS to those simulated by individuals without flashbacks. As predicted, individuals with PTSS reported significantly greater sleep disturbances, experiential avoidance, and lower trait mindfulness than those without PTSS. Individuals without PTSS underestimated the vividness, emotional intensity, distress, and functional impact associated with flashbacks. Consistent with basic-mechanisms theory, we did not find evidence of fragmentation of flashbacks in individuals with PTSS. Additional implications and future directions are discussed.

Longitudinal Changes in Combat-Related Posttraumatic Stress Disorder Among Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn Veterans With Hazardous Alcohol Use: The Role of Avoidance Coping.

Military personnel who have experienced combat trauma are at risk for developing posttraumatic stress disorder (PTSD). A greater recognition of the complex array of vulnerability factors that contribute to PTSD severity has led researchers to examine other non-combat-related factors. This longitudinal study examined a number of pre-, peri-, and postdeployment factors hypothesized to contribute to PTSD symptomatology among returning Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn veterans presenting with at least subthreshold PTSD symptoms and hazardous alcohol use in a primary care setting. Purported risk factors included childhood family environment, severity of combat exposure, postdeployment social support, alcohol dependence severity, and an avoidant coping style. At baseline, postdeployment social support and avoidant coping contributed to PTSD severity. Only avoidant coping was associated with changes in PTSD symptom at 1-year follow-up. Reducing avoidant coping may deter the maintenance of PTSD among veterans with PTSD symptoms and hazardous alcohol use.

Pilot study comparing telephone to in-person delivery of cognitive-behavioural therapy for trauma-related insomnia for rural veterans

Introduction It is estimated that 70% of patients with posttraumatic stress disorder (PTSD) have chronic insomnia. A recent meta-analysis examined cognitive-behavioural therapy for insomnia (CBT-I) in veterans with and without PTSD, and suggested that most studies had questionable methodology, but generally supported its effectiveness in this population. Further, while CBT-I via telehealth (i.e. using telecommunication and information technology to deliver health services) has shown effectiveness for primary insomnia, it has not been applied to PTSD-related insomnia. Methods Veterans with insomnia who were diagnosed with PTSD (n = 12) or having significant subthreshold PTSD symptoms (n = 6) on the Clinician Administered PTSD Scale were randomly assigned to receive CBT-I in-person (n = 7) or by telephone (n = 11), to pilot test the potential effectiveness, acceptability, and feasibility of administering CBT-I in rural veterans. A six-week CBT-I protocol was delivered, and the veteran’s insomnia was assessed at post-treatment and follow-up. Results Given the small sample size, Cohen’s d was used to detect group differences, finding large effect sizes favouring the in-person delivery, until three-months post-treatment when this difference diminished. Most veterans found the treatment acceptable, regardless of mode of delivery. Based on the results, a larger project is feasible. Feasibility for a larger project is favourable. Discussion In summary, our findings uphold and extend previous research. Specifically, current pilot data suggest that telephone-delivered CBT-I may be able to reduce trauma-related insomnia symptoms. Future trials are needed to assess the effectiveness of CBT-I delivered to rural veterans with posttraumatic insomnia.

An App a Day Keeps the Doctor Away: Guided Education and Training via Smartphones in Subthreshold Post Traumatic Stress Disorder.

Post traumatic stress disorder (PTSD) symptoms are common in military service members (SMs), but stigma can impede treatment initiation. Smartphone applications (apps) are available anywhere, anytime, with the potential to both mitigate the impact of stigma and reduce PTSD symptom severity. We provided 144 SMs or family members, with subthreshold PTSD symptoms (PTSD Checklist [PCL] scores of 28-49), with apps promoting psychoeducation, social engagement, and relaxation and randomized them to 6 weeks of resilience enhancement (brief cognitive-behavioral session, followed by daily text messages directing app use) or a control group (daily text messages of inspirational quotes). Participants (54 percent males, 87 percent SMs) in both groups reported reductions in PTSD, anxiety, and depression symptoms during the 6-week intervention, which were sustained at 3 months, but exhibited partial rebound at 6-12 months. Our preliminary results suggest that app use, with or without specific direction, feasibly and effectively reduces symptom severity. Future studies should consider a longer intervention, enhanced compliance tracking, or boosters to sustain benefits.

Post-traumatic stress disorder dimensions and asthma morbidity in World Trade Center rescue and recovery workers

ABSTRACTObjective: Using data from a cohort of World Trade Center (WTC) rescue and recovery workers with asthma, we assessed whether meeting criteria for post-traumatic stress disorder (PTSD), sub-threshold PTSD, and for specific PTSD symptom dimensions are associated with increased asthma morbidity. Methods: Participants underwent a Structured Clinical Interview for Diagnostic and Statistical Manual to assess the presence of PTSD following DSM-IV criteria during in-person interviews between December 2013 and April 2015. We defined sub-threshold PTSD as meeting criteria for two of three symptom dimensions: re-experiencing, avoidance, or hyper-arousal. Asthma control, acute asthma-related healthcare utilization, and asthma-related quality of life data were collected using validated scales. Unadjusted and multiple regression analyses were performed to assess the relationship between sub-threshold PTSD and PTSD symptom domains with asthma morbidity measures. Results: Of the 181 WTC workers with asthma recruited into the study, 28% had PTSD and 25% had sub-threshold PTSD. Patients with PTSD showed worse asthma control, higher rates of inpatient healthcare utilization, and poorer asthma quality of life than those with sub-threshold or no PTSD. After adjusting for potential confounders, among patients not meeting the criteria for full PTSD, those presenting symptoms of re-experiencing exhibited poorer quality of life (p = 0.003). Avoidance was associated with increased acute healthcare use (p = 0.05). Sub-threshold PTSD was not associated with asthma morbidity (p > 0.05 for all comparisons). Conclusions: There may be benefit in assessing asthma control in patients with sub-threshold PTSD symptoms as well as those with full PTSD to more effectively identify ongoing asthma symptoms and target management strategies.

Psychophysiological Investigation of Combat Veterans with Subthreshold Post-traumatic Stress Disorder Symptoms.

Military service members (SMs) with subthreshold combat-related post-traumatic stress disorder (PTSD) symptoms often have clinically significant functional impairment, even though they do not meet full PTSD criteria. We therefore assessed the psychophysical responses of SMs, upon their return from Afghanistan or Iraq, to a fear conditioning paradigm to better understand the biological underpinnings of symptom severity. Heart rate (HR), skin conductance, electromyography startle, and respiratory rate (RR) were monitored throughout three distinct phases of the paradigm-fear acquisition, fear inhibition, and fear extinction-while plasma catecholamines (epinephrine, norepinephrine, and dopamine) were measured at the end of fear inhibition. Those with higher PTSD symptom severity demonstrated elevations in HR and startle response to danger cues; elevated self-reported depression and anxiety; impaired functional status; poor skin conductance discrimination between danger and safety; and increases in HR and RR during fear extinction. Moreover, an inverse relationship was seen between plasma dopamine and HR during fear inhibition for those with high symptoms. Overall, the physiological responses we observed in our subthreshold PTSD population parallel what has been previously observed in full PTSD, making a case for addressing subthreshold PTSD symptoms in combat veterans.

White matter microstructure of the uncinate fasciculus is associated with subthreshold posttraumatic stress disorder symptoms and fear potentiated startle during early extinction in recently deployed Service Members

Early intervention following combat deployment has the potential to prevent posttraumatic stress disorder (PTSD), but there is a need for greater understanding of the factors that contribute to PTSD symptom progression. This study investigated: (1) fear-potentiated startle during a fear extinction, (2) white matter microstructure, and (3) PTSD symptom severity, in 48 recently deployed service members (SMs) who did not have sufficient PTSD symptoms to meet criteria for a clinical diagnosis. Electromyography startle during a conditional discrimination paradigm, diffusion tensor imaging, and the Clinician Administered PTSD Scale were assessed in a cohort of SMs within 2 months after their return from Iraq or Afghanistan. Significant correlations were found between left uncinate fasciculus (UF) white matter tract integrity and total PTSD symptoms, r=−0.343, p=0.018; the left UF and hyperarousal symptoms, r=−0.29, p=0.047; right UF integrity and total PTSD symptoms r=−0.3371, p=0.01; right UF integrity and hyperarousal symptoms r=−0.332, p=0.023; left UF and startle during early extinction, r=.31, p=0.033. Our results indicate that compromise of UF tract frontal-limbic connections are associated with greater PTSD symptom severity and lower startle response during extinction. In a subthreshold population, such a relationship between brain structure, physiological reactivity, and behavioral expression may reveal vulnerabilities that could have significant implications for PTSD symptom development.

Psychophysiological response to virtual reality and subthreshold posttraumatic stress disorder symptoms in recently deployed military.

Subthreshold posttraumatic stress disorder (PTSD) has garnered recent attention because of the significant distress and functional impairment associated with the symptoms as well as the increased risk of progression to full PTSD. However, the clinical presentation of subthreshold PTSD can vary widely and therefore is not clearly defined, nor is there an evidence-based treatment approach. Thus, we aim to further the understanding of subthreshold PTSD symptoms by reporting the use of a virtual combat environment in eliciting distinctive psychophysiological responses associated with PTSD symptoms in a sample of subthreshold recently deployed US service members. Heart rate, skin conductance, electromyography (startle), respiratory rate, and blood pressure were monitored during three unique combat-related virtual reality scenarios as a novel procedure to assess subthreshold symptoms in a sample of 78 service members. The Clinician-Administered PTSD Scale was administered, and linear regression analyses were used to investigate the relationship between symptom clusters and physiological variables. Among the range of psychophysiological measures that were studied, regression analysis revealed heart rate as most strongly associated with Clinician-Administered PTSD Scale-based measures hyperarousal (R = 0.11, p = .035,) reexperiencing (R = 0.24, p = .001), and global PTSD symptoms (R = 0.17, p = .003). Our findings support the use of a virtual reality environment in eliciting physiological responses associated with subthreshold PTSD symptoms.

Connecting combat-related mild traumatic brain injury with posttraumatic stress disorder symptoms through brain imaging

Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) may share common symptom and neuropsychological profiles in military service members (SMs) following deployment; while a connection between the two conditions is plausible, the relationship between them has been difficult to discern. The intent of this report is to enhance our understanding of the relationship between findings on structural and functional brain imaging and symptoms of PTSD. Within a cohort of SMs who did not meet criteria for PTSD but were willing to complete a comprehensive assessment within 2 months of their return from combat deployment, we conducted a nested case–control analysis comparing those with combat-related mTBI to age/gender-matched controls with diffusion tensor imaging, resting state functional magnetic resonance imaging and a range of psychological measures. We report degraded white matter integrity in those with a history of combat mTBI, and a positive correlation between the white matter microstructure and default mode network (DMN) connectivity. Higher clinician-administered and self-reported subthreshold PTSD symptoms were reported in those with combat mTBI. Our findings offer a potential mechanism through which mTBI may alter brain function, and in turn, contribute to PTSD symptoms.

A Pilot Study of a Randomized Controlled Trial of Yoga as an Intervention for PTSD Symptoms in Women

Posttraumatic stress disorder (PTSD) is a debilitating condition that affects approximately 10% of women in the United States. Although effective psychotherapeutic treatments for PTSD exist, clients with PTSD report additional benefits of complementary and alternative approaches such as yoga. In particular, yoga may downregulate the stress response and positively impact PTSD and comorbid depression and anxiety symptoms. We conducted a pilot study of a randomized controlled trial comparing a 12-session Kripalu-based yoga intervention with an assessment control group. Participants included 38 women with current full or subthreshold PTSD symptoms. During the intervention, yoga participants showed decreases in reexperiencing and hyperarousal symptoms. The assessment control group, however, showed decreases in reexperiencing and anxiety symptoms as well, which may be a result of the positive effect of self-monitoring on PTSD and associated symptoms. Between-groups effect sizes were small to moderate (0.08-0.31). Although more research is needed, yoga may be an effective adjunctive treatment for PTSD. Participants responded positively to the intervention, suggesting that it was tolerable for this sample. Findings underscore the need for future research investigating mechanisms by which yoga may impact mental health symptoms, gender comparisons, and the long-term effects of yoga practice.

Occurrence of delayed-onset post-traumatic stress disorder: a systematic review and meta-analysis of prospective studies

Post-traumatic stress disorder (PTSD) develops according to consensus criteria within the first 1-6 months after a horrifying traumatic event, but it is alleged that PTSD may develop later. The objective was to review the evidence addressing occurrence of PTSD with onset >6 months after a traumatic event (delayed-onset PTSD). Through a systematic search in PubMed, EMBASE, and PsycINFO, we identified 39 studies with prospective ascertainment of PTSD. A meta-analysis was performed in order to obtain a weighted estimate of the average proportion of delayed-onset PTSD cases, and meta-regression was used to examine effects of several characteristics Delayed-onset PTSD was reported in all studies except one, and the average prevalence across all follow-up time was 5.6% [95% confidence interval (95% CI) 4.3-7.3%]. The proportion with delayed-onset PTSD relative to all cases of PTSD was on average 24.5% (95% CI 19.5-30.3%) with large variation across studies. In six studies with sub-threshold symptom data, delayed-onset PTSD seemed most likely an aggravation of early symptoms. The proportion with delayed-onset PTSD was almost twice as high among veterans and other professional groups compared to non-professional victims. Descriptive follow-up data suggest that PTSD may manifest itself >6 months after a traumatic event, delayed-onset PTSD most often, if not always, is preceded by sub-threshold PTSD symptoms, and a higher proportion of PTSD cases are delayed among professional groups. Contextual factors and biased recall may inflate reporting of PTSD and a cautious interpretation of prevalence rates seems prudent.

Heart rate response to fear conditioning and virtual reality in subthreshold PTSD.

Posttraumatic stress disorder (PTSD) is a significant health concern for U.S. military service members (SMs) returning from Afghanistan and Iraq. Early intervention to prevent chronic disability requires greater understanding of subthreshold PTSD symptoms, which are associated with impaired physical health, mental health, and risk for delayed onset PTSD. We report a comparison of physiologic responses for recently deployed SMs with high and low subthreshold PTSD symptoms, respectively, to a fear conditioning task and novel virtual reality paradigm (Virtual Iraq). The high symptom group demonstrated elevated heart rate (HR) response during fear conditioning. Virtual reality sequences evoked significant HR responses which predicted variance of the PTSD Checklist-Military Version self-report. Our results support the value of physiologic assessment during fear conditioning and combat-related virtual reality exposure as complementary tools in detecting subthreshold PTSD symptoms in Veterans.

Attention to threat images in individuals with clinical and subthreshold symptoms of post-traumatic stress disorder

Attention to general and trauma-relevant threat was examined in individuals with clinical and subthreshold symptoms of post-traumatic stress disorder (PTSD). Participants’ eye gaze was tracked and recorded while they viewed sets of four images over a 6-s presentation (one negative, positive, and neutral image, and either a general threat image or a trauma-relevant threat image). Two trauma-exposed groups (a clinical and a subthreshold PTSD symptom group) were compared to a non-trauma-exposed group. Both the clinical and subthreshold PTSD symptom groups attended to trauma-relevant threat images more than the no-trauma-exposure group, whereas there were no group differences for general threat images. A time course analysis of attention to trauma-relevant threat images revealed different attentional profiles for the trauma-exposed groups. Participants with clinical PTSD symptoms exhibited immediate heightened attention to the images relative to participants with no-trauma-exposure, whereas participants with subthreshold PTSD symptoms did not. In addition, participants with subthreshold PTSD symptoms attended to trauma-relevant threat images throughout the 6-s presentation, whereas participants with clinical symptoms of PTSD exhibited evidence of avoidance. The theoretical and clinical implications of these distinct attentional profiles are discussed.

Prevalence of post-traumatic stress disorder among the inpatients in a tertiary clinic and relationship with suicidal attempts

ObjectiveTo determine traumatic experiences, prevalence of post-traumatic stress disorder (PTSD) among psychiatric inpatients in a tertiary clinic and the relationship between suicidal attempts. Material and methodsWhile a total of consecutive 175 patients (97 females, 78 males) who were hospitalized in the clinic for a period of six months were being assessed with usual diagnostic processes, they also filled out Posttraumatic Diagnostic Scale (PDS) and socio-demographic assessment form. ResultsWhile diagnosis of PTSD was made in 0.017% of the patients when they were evaluated with usual diagnostic methods of the clinic, 63.8% of females and 64.1% of males reported traumatic experiences when they were evaluated through scales. 30.3% of patients met criteria for PTSD according to PDS, and 8% of patients reported subthreshold PTSD symptoms. There was the history of suicidal attempts in 40.2% of females and in 30.8% of males. When evaluated with regression analysis, presence of PTSD according to PDS, physical violence, emotional abuse, exposure to economic abuse and high scores of PDS were found to be predictive factors for suicidal attempt. Three subjects who did not report traumatic experiences at the time of hospitalization reported sexual trauma during outpatient follow up. ConclusionPTSD is common among hospitalized psychiatric patients; diagnosis of PTSD is usually related with suicidal attempt. Diagnosis of PTSD is not recognized in many cases unless investigated especially.

Post-traumatic disorder symptoms and blunted diurnal cortisol production in partners of prostate cancer patients

Prostate cancer (PC) is the most common cancer diagnosed in men, and research suggests that coping with this illness can cause significant distress in patients as well as their partners. This study examined the relationship of caregiving for a partner with PC with diurnal cortisol output in women between the ages of 42 and 75 years old. Participants were women whose partners had PC (n = 19) and women who were in relationships with men with no diagnosed medical illness (n = 26). Women provided saliva samples (4 times per day over 3 days) in their natural environment. The Structured Clinical Interview for DSM-IV Axis-I Disorders was also conducted to assess for the presence of post-traumatic stress disorder (PTSD) and major depression. Partners of men with PC had lower daily cortisol output across the three days than controls, F(1,444.08) = 20.72, p<.001). They were also more likely to report PTSD symptoms with 68.4% of PC partners fulfilling criteria for sub-threshold PTSD as compared to 23.1% of controls (χ(2) = 11.30, p = .01). Mixed model analyses revealed that the presence of sub-threshold PTSD symptoms significantly predicted cortisol production, F(1,419.64) = 5.10, p<.01). Regardless of caregiver status, women who reported at least sub-threshold PTSD symptoms had lower cortisol production than those with no PTSD symptoms. Major depression did not explain differences in cortisol production between partners of PC patients and controls. Although these findings are preliminary, they highlight the importance of developing interventions aimed at reducing risk of psychopathology in partners of men with PC.

Examining posttraumatic stress symptoms in a national sample of homicide survivors: Prevalence and comparison to other violence victims

The present study examined posttraumatic stress disorder (PTSD) symptoms among friends and family members of homicide victims (homicide survivors). Out of a national sample of 1,753 young adults who completed follow-up interviews after participating in the National Survey of Adolescents, 268 homicide survivors and 653 victims of other interpersonal violence were selected for the study. Participants completed structured telephone interviews that covered the loss of a family member or close friend to homicide, violence exposure, and PTSD symptomatology. Findings indicated that 39% of homicide survivors met criteria for all 3 symptom clusters and 30% of homicide survivors met criteria for 2 PTSD clusters (functional impairment was not assessed). Multivariate logistic regression analyses demonstrated that homicide survivors were more likely than victims of other violence to meet criteria for all 3 PTSD symptom clusters (OR = 1.91, p < .05) and 2 symptom clusters (OR = 1.77, p < .05) when demographic characteristics and number of violent events were included in the model. These findings highlight the high prevalence of subthreshold PTSD symptoms among homicide survivors. Results suggest that homicide survivors are at elevated risk for PTSD symptoms in comparison to victims of other interpersonal violence.

Pathological Gambling and Posttraumatic Stress Disorder: A Study of the Co-Morbidity versus Each Alone

This report is the first empirical study to compare pathological gambling (PG), posttraumatic stress disorder (PTSD), and their co-occurrence. The sample was 106 adults recruited from the community (35 with current PG; 36 with current PTSD, and 35 with BOTH). Using a cross-sectional design, the three groups were rigorously diagnosed and compared on various measures including sociodemographics, psychopathology (e.g., dissociation, suicidality, comorbid Axis I and II disorders), functioning, cognition, life history, and severity of gambling and PTSD. Overall, the PG group reported better psychological health and higher functioning than PTSD or BOTH; and there were virtually no differences between PTSD and BOTH. This suggests that it is the impact of PTSD, rather than comorbidity per se, that appears to drive a substantial increase in symptoms. We also found high rates of additional co-occurring disorders and suicidality in PTSD and BOTH, which warrants further clinical attention. Across the total sample, many reported a family history of substance use disorder (59%) and gambling problems (34%), highlighting the intergenerational impact of these. We also found notable subthreshold PTSD and gambling symptoms even among those not diagnosed with the disorders, suggesting a need for preventive care. Dissociation measures had mixed results. Discussion includes methodology considerations and future research areas.