Mental disorders are common in individuals suffering from chronical physical conditions, with symptoms of depression being most prevalent (Deschênes et al., 2015). Particularly psychosomatic diagnoses have been found to be the most common cause of disability pensions in the past years (Dannenberg et al., 2010). As a result, early retirement or extensive psychosocial and vocational rehabilitation programs may be necessary in order to restore work capacity and well-being (Köllner, 2014; Linden, 2014).

Connected to this notion, cognitive functions, such as the working memory (WM) have been found to be impaired in a range of psychosomatic and mental disorders. The WM is a prominent system central to cognitive functioning with limited capacity and is, therefore, restricted in how much information can be actively held in WM (Eriksson et al., 2015). Recent evidence indicates that the WM is frequently impaired in psychosomatic disorders (Haley et al., 2008; Schmitz et al., 2008) as well as in mental disorders, including depression (Snyder, 2013) and anxiety (Moran, 2016). For example, Wagner et al. (2006) found cognitive impairments in 24% of the patients from a rehabilitation clinic who suffered from psychosomatic and mental disorders. These results highlight that especially in patients with psychosomatic disorders, impairments in WM functioning may be even more disabling, a fact that might further impact the rehabilitation process (Wagner et al., 2006; Köllner, 2014).

In the past decades, research has identified various factors contributing to WM impairments, one of them being repetitive negative thinking (RNT; Snyder, 2013; Moran, 2016; Zetsche et al., 2018) which has been found in a range of mental disorders (McEvoy et al., 2013) as well as in psychosomatic populations (Trick et al., 2016). RNT is characterized by repetitive thinking about negative topics which is experienced as difficult to control (Ehring and Watkins, 2008). It has been proposed that RNT occupies available WM capacities by acting as a dual task and thereby leading to impaired WM functioning (Beckwé et al., 2014; Zetsche et al., 2018). Indeed, WM impairments have been consistently observed in individuals suffering from a mental disorder when engaging in RNT (Watkins and Brown, 2002; Joormann and Gotlib, 2008; Gustavson and Miyake, 2015; Sari et al., 2016). However, to date, no study has investigated the effect of RNT of WM performance in psychosomatic populations.

In addition, a growing amount of evidence suggests that depressive symptomatology might be another relevant factor contributing to WM impairments (Wagner et al., 2006; Snyder, 2013). The majority of studies investigated outpatients with depressive disorders and found significant associations between depressive symptoms and WM deficits (Christopher and MacDonald, 2005; Joormann and Gotlib, 2008). However, to the best of our knowledge, only one study investigated the effects of depressive symptoms on WM performance in psychosomatic inpatients (Wagner et al., 2006). The results of this study indicated that subjective memory impairments were most pronounced in psychosomatic patients with depressive symptoms.

Taken together, although there is substantial evidence suggesting that WM impairments in individuals with mental disorders may result from interference with cognitive processes (i.e., RNT) and severe clinical symptoms (i.e., depression) there seems to be a lack of studies investigating these concepts in patients with psychosomatic disorders. The majority of studies investigated outpatients (Joormann and Gotlib, 2008) and it still unclear whether WM functioning is affected in psychosomatic inpatients or not. As pointed out above, many psychosomatic patients are adult individuals who are unable to work and therefore, considering these characteristics (age and inability to work), it might further be of importance to investigate WM performance. Moreover, the majority of participants in the past studies were either young adults (30–40 years) or older patients (70 years) and therefore, we have limited information about how these mechanisms manifests in adults more generally (Mattay et al., 2006). Finally, few studies assessed WM performance in more than one WM block (i.e., assessing more than 15 min; Sari et al., 2016) and one advantage of using two blocks over the standard use of one block is the ability to examine the WM performance stability across the two block (Scharfen et al., 2018).

This study seeks to investigate WM performance in psychosomatic inpatients who referred to a psychosomatic rehabilitation clinic. All participants performed a WM task which consisted of two blocks (WM Block 1 and 2) lasting in total 30–40 min. Block denotes a complete WM task which is usually performed by participants as a single task (e.g., Sari et al., 2016). WM performance was measured as accuracy and reaction time. First, we explore the change of accuracy and reaction time in WM from Block 1 to Block 2 (Research Question 1; RQ1). Second, we explore the potential relevance of cognitive factors (RNT), depressive symptom severity, age and incapability to work on accuracy and reaction time (RQ2).

Descriptive statistics and correlations of key variables are displayed in Supplementary Table 1A. To analyse the subjective workload as well as the emotional experiences during the assessment, each item from the extended NASA was analyzed individually in univariate multilevel models with a random intercept. Results indicate that from T1 (before Block 1) to T2 (after Block 1), patients felt significantly more alert [t (150) = 2.97, p = 0.003], more interested [t (150) = 2.35, p = 0.01], less afraid [t (150) = −2.83, p = 0.005], less distressed [t (150) = −2.79, p = 0.005], but also more jittery [t (148) = 2.10, p = 0.04; Supplementary Table 2A]. After Block 2 at T3, patients’ rating of physical demands and level of effort were significantly higher in comparison to T1 [physical demands: t (75) = 2.19, p = 0.03; effort: t (75) = 2.55, p = 0.01].

There is cumulative evidence suggesting that WM performance is impaired in individuals suffering from a psychosomatic or mental disorder (Snyder, 2013; Moran, 2016). The present study examines WM performance in a two-block WM task (Block 1 and Block 2) in highly distressed psychosomatic inpatients and results indicate that RNT, depressive symptoms and patient age is associated with lower WM performance.

First, we observed a significant decrease in accuracy as well as in reaction time over the course of the WM task (RQ1), meaning that patients made more errors but at the same time became faster in their answering speed from Block 1 to Block 2. One possible explanation for this finding might be the nature of the task itself: Initially, when confronted with an unknown WM task, patients may have perceived the situation as highly stressful (Eysenck et al., 2007). However, during Block 1, patients may have gotten familiar with the task and gained confidence to increase their answering speed. Indeed, participants indicated feeling less distressed and less afraid in the self-reports. When the WM task continued in Block 2, patients indicated an increase in physical task demands and a higher level of effort. As a result, patients may have made more errors. However, since this is a starting point of understanding WM processing across two blocks, future research is needed to better understand WM functioning across two- or more blocks.

With regard to RQ2, we found that patients who reported higher RNT scores as well as more severe depressive symptoms showed lower accuracy scores in Block 1. This is in line with recent meta-analytic evidence indicating that individuals with high RNT seem to have impaired WM performance, specifically, in difficulty in discarding no longer relevant material from WM (k = 94; Zetsche et al., 2018). However, Zetsche et al. (2018) only obtained low correlations between measures of psychopathology (i.e., anxiety and depression) and WM deficits, but hypothesize that they may have underestimated this relation by summarizing correlation coefficients within diagnostic groups, resulting in limited variance. Indeed, our results indicate that WM impairments may even be greater in psychosomatic patients with high depressive symptoms which confirms previous work in this field (Christopher and MacDonald, 2005; Wagner et al., 2006). Taken together, the results highlight that RNT and depressive symptoms seems to be relevant factors affecting WM performance in psychosomatic inpatients.

Furthermore, we found that older patients made significantly more errors (i.e., lower accuracy) in Block 1. These results are in line with prior findings which indicate a progressive effect between age and mental disorders, leading to a decreased WM performance (Snyder, 2013). Therefore, particularly in older employees suffering from psychosomatic disorders, WM impairments might be particularly challenging. Moreover, our results indicate that duration of work incapability prior to clinic admission did not affect WM performance. In a similar study, Wagner et al. (2006) did not find differences between psychosomatic patients with or without memory impairments with regard to capability to work at discharge. Taken together, the present results highlight the need to consider multiple factors, such as age, symptom severity and their potential interaction when assessing WM functioning across adulthood.

There are several limitations to consider when interpreting the results of this study. First, the recruitment context might impact the representativeness of the sample: Participation in the WM assessment was solely voluntary; therefore, it is possible that only those not so severely impaired signed up for participation. By assessing WM functions as a standardized part of intake and discharge assessments in clinics, it could further help shaping the treatment according to the patients’ cognitive abilities (Beblo, 2002). Moreover, integrating cognitive training programs focusing on compensating and improving WM functioning within the psychosomatic rehabilitation context could be beneficial (Wagner et al., 2008). Second, we did not recruit a comparison group (i.e., ambulatory or healthy participants). Hence, in order to be able to disentangle how RNT influences WM functioning, it would be helpful to investigate individuals with more variability in RNT and/or (sub-)clinical symptoms. Third, the majority of the patients were female and a contrast between gender would be underpowered based on the obliquely distributed characteristic and the limited sample size. Therefore, we were not able to rule out potential gender differences for this particular WM task. Forth, even though we used a WM task whose practicality was previously tested in patient samples, fatigue effects (e.g., Li et al., 2020) and further aspects of the self-paced format could have an impact on the particular WM task (e.g., Bailey, 2012).

To conclude, the present study investigated WM performance in an adult psychosomatic inpatient population and found that RNT, depressive symptom severity and age significantly is associated with lower WM functioning. Assessing WM functioning may help to better personalize treatment planning in psychosomatic populations in respect to their challenges in psychosocial functioning and work conditions.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the ethical committee of the Federal Medical Association (“Landesärztekammer”) of Brandenburg. The patients/participants provided their written informed consent to participate in this study.

All authors were involved in conceptualizing and writing up this study report. JH, LR, VK, and CF were responsible for the study conceptualization. JH performed the data analysis and was the major responsible in writing up the manuscript. LR was responsible for the data collection and preliminary analyses. CF and VK were the principal investigators. CF, AV, PH, and VK provided advice for the data analysis and study report.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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