Validation of the German Version of the Mind Excessively Wandering Scale (MEWS-G).

Increasing evidence shows that unintentional mind wandering is linked to Attention Deficit Hyperactivity Disorder (ADHD) and that its frequency contributes to symptom severity and functional impairment in ADHD. However, empirical data on mind wandering in adult ADHD are still scarce, and a validated scale to assess mind wandering in German adult ADHD patients is lacking. The primary aim of this study is to assess the psychometric properties of the German version of the recently published Mind Excessively Wandering Scale (MEWS-G) in terms of factorial structure and factor stability, internal consistency and construct validity. Analyses were performed in 128 adults with ADHD, clinical and healthy controls. As described for the original English 15-item version of the scale, we found lowest item-total-correlations for items 6, 10 and 14 with item-total correlation of all: 0.54/ADHD: 0.32 (item 6), all: 0.55/ADHD: 0.39 (item 10) and all: 0.11/ADHD: -0.04 (item 14). Item-total correlations for the remaining items were 0.65-0.86 and Cronbach Alpha was 0.96 indicating good internal consistency of the 12-item version of scale, on which we based all further analyses. Principal component analysis indicated a one- and two- factorial scale structure respectively explaining 71.7 % and 78.7 % of variance. Both factors showed good stability with lower stability of the factor-2 solution if sample size was reduced. The two-factorial solution also had many cross-loadings and a strong correlation of both factors in confirmatory factorial analysis (rf1f2 = 0.87). It probably describes related and interdependent, but not distinct facets of mind wandering, which strongly argues for the one factorial structure of the scale. Mean MEWS-G score in ADHD was 23.77 ± 7.85 compared to 7.64 ± 7.27 in controls (p < .0001). According to ROC, the optimal cut-off point to discriminate ADHD and controls is at MEWS-G score = 13. On the symptom level, MEWS-G score was correlated with ADHD, depressive and total psychiatric symptom scores, on the personality level with neuroticsm and negatively with conscientiousness and on the functional level with social interaction difficulties and impaired self-efficacy. In summary, our study shows that MEWS-G is a reliable, valid instrument to assess spontaneous mind wandering in adult ADHD and to discriminate between ADHD and controls.