Objective This study aims to provide effect size estimates of the impact of two cognitive rehabilitation interventions provided to patients with mild cognitive impairment: computerized brain fitness exercise and memory support system on support partners' outcomes of depression, anxiety, quality of life, and partner burden. Methods A randomized controlled pilot trial was performed. Results At 6 months, the partners from both treatment groups showed stable to improved depression scores, while partners in an untreated control group showed worsening depression over 6 months. There were no statistically significant differences on anxiety, quality of life, or burden outcomes in this small pilot trial; however, effect sizes were moderate, suggesting that the sample sizes in this pilot study were not adequate to detect statistical significance. Conclusion Either form of cognitive rehabilitation may help partners' mood, compared with providing no treatment. However, effect size estimates related to other partner outcomes (i.e., burden, quality of life, and anxiety) suggest that follow‐up efficacy trials will need sample sizes of at least 30–100 people per group to accurately determine significance. Copyright © 2017 John Wiley & Sons, Ltd.