Objective: We evaluated the ability of the three cognitive training interventions (memory, reasoning, or speed of processing) fielded in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) multisite randomized controlled trial to protect against two thresholds of extensive decline in health-related quality of life (HRQoL) at 2 and 5 years post-training.
Method: Adults aged 65 years or older (2802) were enrolled and randomized to three cognitive interventions or a no-contact control group. Data on 1804 participants were available at both the 2- and 5-year follow-ups. HRQoL was measured by the eight MOS 36-Item Short-Form Health Survey (SF-36) scales. Clinically relevant decline on each scale was defined as a drop of > or = 0.5 standard deviations from baseline. Extensive HRQoL decline was defined as clinically relevant drops on (i) > or = 4 SF-36 scales, and (ii) > or = 3 SF-36 scales, and was assessed using multiple logistic regressions, weighted to adjust for potential attrition bias. Results. At 2 years post-training, 23.7% and 36.6% had clinically relevant drops on > or = 4 and > or = 3 SF-36 scales, respectively. At 5 years post-training, 32.9% and 47.3% had clinically relevant drops on > or = 4 and > or = 3 SF-36 scales, respectively. Participants in the speed of processing intervention arm were significantly less likely to have extensive HRQoL decline compared to participants in the control group regardless of the threshold or time period, whereas participants in the memory and reasoning intervention arms were significantly less like to have extensive HRQoL decline only at 5 years post-training and only at the lower threshold. Conclusion. The effect of the speed of processing intervention was stronger and evident earlier than those for the memory and reasoning interventions. This result stems from the speed of processing intervention being the most procedural intervention, operating through sensory-motor elaboration and repetition, bringing about a broader pattern of regional brain activation. At 5 years post-training, however, all three interventions were successful in protecting against a lower threshold of age-related extensive declines in HRQoL.