Examination on Brain Training Method: Effects of n-back task and dual-task [version 1; peer review: 1 not approved]

Background: Alzheimer's dementia (AD) is the most common dementia, accounting for more than 60% of all dementia cases. For adults aged >65 years, the incidence rate doubles for every 5 years of increased age; therefore, preserving cognitive function is a pressing issue. Thus, our team screens for AD in older adults with mild cognitive impairment, at 11 public halls in Kashihara City, Japan, and offers follow-up to those with cognitive difficulties. The purpose of this research was to measure the effects of two interventions, a dual-task (requiring the participant to perform two tasks at the same time) and an n-back task (test of memory retention, requiring the participant to identify the item occupying the nth-back position in a sequence of items). A comparison group performed a single learning task in place of the dual-task. Moreover, the majority of non-drug therapies for the maintenance of cognitive function help promote a positive mood, activating reward systems in the brain and motivating the individual to continue the task. Therefore, the correlation between cognitive function, and positive and negative mood was investigated. Methods: Dual and n- back task (n = 304) and single-task (n = 78) groups were compared in a 6-month intervention. Salivary α-amylase concentration was measured, which reflects positive and negative mood, and correlations with cognitive function were analyzed. Results: Cognitive function improved in both the dual-task and the single-task groups, and many cognitive domains had improved in the dual-task group. A correlation between salivary α-amylase and cognitive function was found, indicating that a greater positive mood was associated with greater cognitive function. Conclusion: The results of this research show that functional decline can be improved by a cognitive intervention. Positive mood and cognitive function were correlated, suggesting that encouraging comfort in the participant can increase the effectiveness of the intervention.