Performance-Based Versus Informant-Reported IADL in Dementia: A Person–Environment–Occupation Perspective for Occupational Therapy Outcome Selection

Objectives Selecting an instrumental activities of daily living (IADL) outcome is important in occupational therapy intervention for older adults with dementia. Inspired by the Person–Environment–Occupation (PEO) framework, this study compared older adults with AD and non-AD dementia on performance-based and informant-reported IADL outcomes and examined correlates by group. Methods Eighty older adults with mild-to-moderate dementia (49 AD; 31 non-AD: 17 vascular dementia, 14 dementia with Lewy bodies) and 30 controls were recruited in Taiwan. Cognition, physical performance, neuropsychiatric symptoms, and caregiver distress were assessed with the Montreal Cognitive Assessment (MoCA), modified Physical Performance Test, and Neuropsychiatric Inventory. IADL was measured using Taiwan Performance-based IADL (TPIADL) and the Disability Assessment for Dementia–IADL (DAD-IADL). ANCOVA was used to compare groups, hierarchical regression was used to examine correlates, and Pearson correlations was used to examine within-group TPIADL–DAD-IADL associations. Results AD and non-AD participants had comparable cognitive, physical, and neuropsychiatric profiles. Non-AD participants had poorer DAD-IADL scores ( p = .019), whereas TPIADL did not differ ( p = .256). TPIADL and DAD-IADL were correlated in AD ( r = −.697, p < .001) and non-AD dementia ( r = −.374, p = .038). MoCA was the only consistent correlate of TPIADL (β = −.66 to −.87). For DAD-IADL, MoCA was the primary correlate in AD (β = .57), whereas hyperactivity (β = .59) and caregiver distress (β = −.58; ΔR 2 = .287) were identified in non-AD. Conclusion Performance-based and informant-reported IADL measures may provide complementary information about occupational performance in older adults with dementia. Their associations may be interpreted within the PEO framework as reflecting person-related and contextual influences.