A Novel Rating Scale for the Measurement of Apathy in Institutionalized Persons with Dementia: The APADEM-NH

Apathy is one of the most frequent symptoms of dementia, still needing better measurement methods. The objective of this study was to validate a new scale for apathy in institutionalized persons with dementia (APADEM-NH). Methods: The scale includes 26 items distributed in three dimensions: Deficit of Thinking and Self-Generated behaviors (DT): 13 items, Emotional Blunting (EB): 7 items, and Cognitive Inertia (CI): 6 items. The sample included 100 institutionalized patients (90% female) with probable Alzheimer disease (AD) (57%), possible AD (13%), AD + cerebral vascular disease (17%), Lewy body dementia (11%), and Parkinson associated to dementia (2%), covering all stages of dementia severity according to the Global Deterioration Scale and Clinical Dementia Rating. Additional assessments were the Apathy Inventory, Neuropsychiatric Inventory, Cornell Scale for Depression, and the tested scale. Re-test and inter-rater reliability were carried out in 50 patients. Results: All subscales lacked relevant floor and ceiling effects (<15%). Internal consistency for each dimension was (Cronbach's alpha): DT = 0.88, EB = 0.83, CI = 0.88; item-total correlations were >0.40; and item homogeneity 0.36-0.51. Test-retest reliability for the items was k(W) = 0.48-0.92; for the subscales, intraclass correlation coefficient (ICC) - 0.80-0.88; and for the total score, ICC = 0.90. Inter-rater reliability reached kW values of 0.84-1.00; subscales ICC, 0.97-0.99, and total score ICC, 0.99. Standard error of measurement for total score was 6.41 and internal validity ranged from r(S) = 0.69-0.80. Conclusions: APADEM-NH proved to be feasible, reliable, and valid for apathy assessment in institutionalized patients suffering mild to severe dementia, discerning well between apathy and depression.