Developing a Measure of Sluggish Cognitive Tempo, a Comorbid Symptoms of ADHD in Adults: Discrimination from Depression

Abstract

This study developed and validated a measure of sluggish cognitive tempo (SCT) for adults, which is a comorbid symptom in about half of the adults with ADHD. The aim of this new measure was to overcome the shortcoming of existing scales to discriminate SCT from depression due to contaminated items. The items to measure SCT were identified by a literature review, and their content validity was evaluated by experts. The items were rated in reference to situations when the participants were not depressed. Responses of 471 undergraduate students were used for factor analyses to help select the items. The results of a joint factor analysis, combining depression items and SCT items, showed that this new measure of SCT for adults demonstrated a good ability to discriminate SCT from depression. The resultant 9-item SCT scale showed adequate convergent validity, discriminant validity, and internal consistency.