Reliability of the Two-dimensional Mood Scale for self-reported mood assessment by older adults with dementia

The purpose of this study was to evaluate the reliability of the Two-dimensional Mood Scale (TDMS) for mood assessment among older adults with dementia. The study included 100 elderly patients with dementia admitted to two hospitals. For each mood state measured by the TDMS, the intraclass correlation coefficient of agreement (ICC_agreement) was calculated to evaluate test-retest reliability. Scores corresponding to the minimal detectable change (MDC) in each mood state at the individual level (MDC_ind) was also calculated to evaluate measurement error, while McDonald's omega was calculated to evaluate internal consistency. The TDMS ICC was 0.54 for vitality, 0.74 for stability, 0.70 for pleasure, and 0.55 for arousal. The MDC_ind was 6.89 for vitality, 5.88 for stability, 9.96 for pleasure, and 4.11 for arousal. McDonald's omega ranged from 0.60 to 0.84. The TDMS has generally acceptable reliability for the self-assessment of mood states by older adults with dementia.