Does Dosage Drive Durability? A Longitudinal Study on Digital Cognitive Training for Sustained Functional Independence

Background: This study aimed to investigate whether a higher cumulative dose of digital cognitive training leads to greater and more sustained improvements in cognition and functionality among older adults with Mild Neurocognitive Disorder. Methods: We recruited participants aged 60 or older with mild neurocognitive disorder to a double-blinded, randomized, stepped wedge clinical trial of digital cognitive training (DCT) compared to an active control group of commercial computer games. Participants were evaluated for functionality and cognition before, after 10 h and 20 h of intervention and in the follow-up. Results: Sixty-seven participants completed DCT and were evaluated. The group that received 20 h of DCT showed significant improvements in functionality and satisfaction, as well as gains in processing speed, verbal fluency, and inhibitory control. The 10 h group also showed improvements in specific areas such as processing speed and recognition. In the 20 h group, the benefits were maintained at 3- and 6-month follow-ups, especially in functionality. Discussion: This study suggests that a higher cumulative dose of DCT may lead to more sustained improvements in functionality performance among older adults with mild neurocognitive disorder. Findings highlight the need for further research to determine optimal training dosage for long-term improvements in cognition and functionality. Trial Registration: The studies reported in the manuscript were pre-registered at ClinicalTrials.gov under the identifier NCT03911765. © 2026 The Author(s). Geriatrics & Gerontology International published by John Wiley & Sons Australia, Ltd on behalf of Japan Geriatrics Society.