## 4 Discussion  
Towards our goal of supporting the independent administration of cognitive training in home and community settings of stroke survivors, we developed a serious game solution, namely _Neuro-World_, and evaluated its therapeutic effectiveness on cognitive function in chronic stroke survivors through  
Figure 3: The means and the standard deviations of the total MMSE score and its category scores at baseline and post-intervention (**a**–**f**). The means and the standard deviations of the DFS, DBS, and GDS scores by groups at baseline and post-intervention (**g**–**i**). a randomized controlled study. The results herein demonstrate that routine use of _Neuro-World_ (i.e., 30 min per day, twice a week) leads to improvements in several aspects of cognitive function, as well as depressive symptoms, in chronic-stage stroke survivors. Specifically, we observed statistically and clinically significant improvements in the total MMSE score [53] and the DBS [54]. We also observed statistically significant improvements in the GDS and all the MMSE sub-categories other than language. However, the improvement in the GDS was not clinically significant [55]. Furthermore, we observed clinically significant improvements, although not statistically significant, in the DFS [54]. In the rest of this section, we discuss in detail the results pertaining specifically to cognitive function (i.e., changes in the total MMSE scores, DFS, and DBS). The discussions related to the results of the sub-categories of MMSE and the GDS could be found in Appendixes D and E.  
Previous randomized controlled studies that investigated the therapeutic effectiveness of cognitive rehabilitation solutions suggest that _Neuro-World_ has yielded comparable or greater improvements in cognitive function. For instance, [PERSON] et al. reported that acute-stage stroke survivors showed a mean improvement of 2.6 points from 22.8 to 25.5 in the MMSE after 16 sessions of one-hour conventional cognitive therapy (i.e., a total of up to 16 h per person) [56]. [PERSON] et al. also showed a mean improvement of 3 points from 24 to 27 in the MMSE after 14 sessions (i.e., a total of up to 15 h of training) of computer-based cognitive therapy [57]. Similarly, [PERSON] et al. reported that 20 sessions (i.e., a total of 10 h) of a combined program of virtual reality-based upper-limb motor rehabilitation and computerized cognitive rehabilitation resulted in a mean improvement of 3.6 MMSE points from 17.4 to 21.0 in acute-phase stroke survivors [58]. Although promising, the improvements reported in the above-mentioned studies--because they involved acute-stage stroke survivors--might have been affected by spontaneous biological recovery during the initial months following the stroke [59]. Furthermore, the reported improvements in MMSE are not particularly greater than the minimal clinically important changes (MCID) that are necessary to conclude clinical significance, which is from 2 to 4 points in MMSE [53]. On the other hand, our study involved stroke survivors who were in the chronic stage with no spontaneous recovery, and the participants in the experimental group showed a mean improvement of 5.93 MMSE points from 21.64 to 27.57 after 24 sessions (e.g., a total of 12 h) of _Neuro-World_. Furthermore, the training dosage used in our study was smaller than previous studies except for the study by [PERSON] et al., which collectively emphasizes the clinical effectiveness and lower burden of _Neuro-World_ in cognitive training. We also demonstrated the therapeutic effectiveness of _Neuro-World_ in improving working memory as assessed by the DBS. Previously, [PERSON] et al. reported that chronic-stage brain injury survivors who completed 25 sessions of 30-45 min (e.g., a total of up to 19 h and 45 min) of _CogMed_--a set of serious games that are specifically designed to train working memory--showed an average increase of 0.61 points in the DBS [60], although the improvement was not greater than the MCID of the DBS (i.e., 1 point) [54]. [PERSON] et al.