Measuring Subjective Vitality and Depletion in Older People from a Self-Determination Theory Perspective: A Dual Country Study

As the global older population grows research increasingly focuses on their well-being and quality of life, aspects that are often impacted by a perceived loss of energy and fatigue. To describe individuals' energy dynamics, Self-Determination Theory (SDT) recently proposed a dual-process model based on two constructs: Subjective Vitality and Depletion. The present study aims to validate the Subjective Vitality/Depletion Scale (SVDS), an SDT instrument based on this model. A sample of 726 older adults (over 65) from two countries USA and Italy (343 USA and 383 Italy; 51.1% females; age range = 65 - 95 years; Mage = 72.57, SDage = 6.49) completed the SVDS, the Big Five Inventory 2 – Extra Short Form (BFI-2-XS), and the 12-item Short Form Health Survey (SF-12). Confirmatory factor analyses of the SVDS support the SDT hypothesis that Subjective Vitality and Depletion are two distinct, yet related constructs. Full measurement invariance for the scale was achieved across gender and age subgroups, while partial scalar invariance was established across different countries, suggesting some specific influence of cultural factors. Correlations with BFI-2-XS and SF-12 support the SVDS convergent, discriminant, and nomological validity. In conclusion, we provided evidence that the SVDS based on SDT is a valid and reliable instrument for assessing Subjective Vitality and Depletion among older individuals. Vitality and Depletion appear to be constructs that are conceptualized and interpreted consistently across older adults with diverse characteristics and cultures.