Abstract
BACKGROUND: Sluggish cognitive tempo (SCT) is associated with-but distinct from-attention-deficit/hyperactivity disorder (ADHD). This study examined SCT rates in adult outpatients seeking an ADHD assessment, differences in rates based on ADHD status, impact of assessment method (i.e., reporting source, symptom count, and functional impairment), and age of SCT symptom onset. METHODS: Outpatients (n = 124) completed an SCT measure (n = 120 other-reporters). SCT was based on reporting source (i.e., self-report, other-report, either reporting source ["or" rule], and both reporting sources ["and" rule]), symptom count (i.e., age-based norms at or near the 93rd percentile, and a higher symptom count threshold of five), and functional impairment (i.e., 0, 1, and ≥2 domains). RESULTS: SCT rates varied based on assessment method for the full sample (26%-82%) and among those with (32%-91%) and without (16%-66%) ADHD. Rates decreased with stricter functional impairment and symptom count criteria. SCT was higher in the ADHD group than the non-ADHD group based on other-reporters and the "or" rule, but not the "and" rule. Functional impairment and symptom count criteria did not impact these comparisons. For self-reported SCT rates, ADHD/non-ADHD group comparisons did not differ based on age-based symptom count threshold, but did with a symptom count threshold of five. Self-reported SCT symptom onset was 13.36 years-old and was significantly younger for the ADHD group (11.69 years) than the non-ADHD group (16.36 years). CONCLUSIONS: Elevated SCT symptoms and related impairment are common among adults seeking an ADHD evaluation. These rates and ADHD/non-ADHD group differences vary substantially based on diagnostic methods.