The D2 Test of Attention and Concentration is a neuropsychological test used to assess selective and sustained attention. It is employed to evaluate an individual's visual scanning, concentration, and information processing speed. The D2 Test involves scoring based on the number of correctly marked items minus the number of errors. The scoring method considers both the quantity and accuracy of responses. The goal is to mark as many target items as possible within a specified time limit while avoiding errors. A higher score is considered a better outcome, indicating more correct responses and effective attention and concentration.

The Sociodemographic Questionnaire (DEMO) is a 30-item questionnaire that was developed to collect sociodemographic (e.g., gender, socioeconomic status, professional status, relationship satisfaction) and health-related data (e.g., medication, inpatient and outpatient treatment).

The Mini-DIPS is a short, structured clinical interview for diagnosing mental disorders and is based on the DIPS-OA. The Mini-DIPS allows for a quick yet reliable diagnosis. It is applicable in adulthood and captures lifetime diagnoses, current and past diagnoses, based on the criteria of DSM-5 and ICD-10. The Mini-DIPS covers the mental disorders most commonly observed in clinical settings.

The Beck Scale for Suicide Ideation (BSS) is a clinical assessment tool designed to measure the severity of suicidal ideation in individuals. It is used in clinical and research settings to assess the risk of suicide. The BSS consists of 19 items, and each item is scored on a 3-point scale (0 to 2). The total score, which ranges from 0 to 38, reflects the severity of suicidal ideation. The minimum score is 0, indicating no suicidal ideation and the maximum score is 38, indicating the highest level of suicidal ideation. Higher scores indicate a greater severity of suicidal ideation, and thus, higher scores are generally associated with a worse outcome.

The Beck Depression Inventory (BDI-II) is a self-assessment questionnaire and contains 21 items which assess the severity of depressive symptoms. A participant's score is calculated by summing up the scores from each item. The total score ranges from 0 to 63. Values between 0 and 11 lie within the norm, between 11 and 17 moderate depressive symptoms and a total score up to 18 is assessed as a clinically relevant depressive disorder.

The Mee-Bunney Psychological Pain Assessment Scale (MBPPAS) is a 10-item self-report questionnaire to assess intensity and frequency of psychological pain. Psychological pain is defined as an experience of unbearable agony which can be linked to a psychiatric disorder. Each of the 10 items is rated on a 5-point Likert scale from 1 (never) to 5 (always) or from 1 (none) to 5 (unbearable). The item scores are added up to a total score. A higher score indicates higher psychological pain.

The General Self-Efficacy Scale (GSE) is a 10-item self-report questionnaire to assess the general sense of self-efficacy. Items are rated from 1 (do not agree) to 4 (totally agree). A higher score indicates a stronger belief in one's ability to cope with and navigate different situations.

The Three-Item UCLA (University of California, Los Angeles) Loneliness Scale is a short questionnaire with three items from the Revised UCLA Loneliness Scale (R-UCLA). These items can be rated from 1 (hardly ever) to 3 (often). A higher score indicates a higher level of perceived loneliness. The scale is designed to measure subjective feelings of loneliness, so individuals who score higher on the UCLA Loneliness Scale report more frequent experiences of loneliness and social isolation.

The Internal-External Locus of Control Short Scale-4 (IE-4) is a brief measure designed to assess an individual's locus of control orientation. Locus of control refers to the extent to which individuals believe they control events in their lives. The IE-4 is typically scored by summing the responses to its four items, each rated on a Likert scale. The possible score range is determined by the specific scoring method researchers or practitioners use. The scores may range from 4 to 16, depending on the scoring system employed. Higher scores on the IE-4 may suggest a more internal locus of control, indicating a belief that one has control over their life events. Lower scores may indicate a more external locus of control, suggesting a belief that external factors or luck play a significant role in life events.

Coping with suicidal ideation and behavior will be assessed with the Suicide-Related Coping Scale (SRCS). The self-report scale SCRS consists of 17 items, with each rated on a five-point Likert scale from "strongly disagree" = 0 to "strongly agree" = 4. A total SRCS sum score is calculated by inverting the negatively worded items and then summing the 17 items. A higher sum score indicates better suicide-related coping.

The German Dissociation-Tension Scale - 4 (DSS-4) is a four-item brief self-report instrument to assess dissociation. It was developed based on the DSS-acute, a longer scale to measure dissociative symptoms. The four DSS-4 items assess somatic and psychological dissociation and each item is rated on a 10-point Likert scale ranging from "not present" = 0 to "very strong" = 9. Based on the DSS-4, a dissociation score per participant is calculated as the mean of the four items.

The Questionnaire for the Analysis of Motivational Schemas (FAMOS) assesses the motivational goals of psychotherapy in terms of central components of motivational schemas in self-report format. The questionnaire FAMOS assesses motivational goals as approach goals on 14 scales and avoidance goals on 9 scales, with a total of 94 items. Each item is rated on a five-point Likert scale. For each scale, the scale mean of the corresponding items is calculated. In addition, three summary values can be calculated: 1) total value for approach goals; 2) total value for avoidance goals; and 3) the ratio of avoidance to approach goals.

The Incongruence Questionnaire (INK) measures unsatisfactory realization of motivational goals, whereas the personal relevance of motivation is measured in the FAMOS. The questionnaire INK assesses the realization of approach and avoidance goals on 14 and 9 scales, respectively, with a total of 94 items. Each item to assess approach goals is assessed on a five-point Likert scale. For each scale, the mean value of the corresponding item values must be determined. In addition, it is possible to calculate three composite scales: 1) incongruence with avoidance goals; 2) incongruence with approach goals; and 3) total incongruence.

The Alcohol Use Disorders Identification Test (AUDIT-C) is an alcohol screen that is used to identify patients who are hazardous drinkers or who may have an active alcohol use disorder. The minimum score (for non-drinkers) is 0, and the maximum possible score is 12. The higher the AUDIT-C score, the more likely it is that the patient's drinking is affecting their health and safety.

Electrodermal activity (EDA), also known as skin conductance or galvanic skin response, is a valuable physiological marker in suicide research. EDA measures the skin's electrical conductance, reflecting sympathetic nervous system activity. Suicidal individuals often experience heightened emotional distress and arousal, challenging assessment via self-reports alone. EDA offers an objective, non-invasive means to quantify this emotional response, with distinct patterns observed in those at risk of suicide.