BACKGROUND: Patients with mild cognitive impairment (MCI) show lower decision making and ratio processing abilities as compared to healthy peers.

OBJECTIVE: To evaluate whether cognitive training on number processing and/or executive functions improves performance on ratio processing and decision making under risk.

METHODS: In a controlled cross-over study, patients with MCI (n = 23; mean MMSE 26.48, SD 2.43) underwent a week of numerical training followed by a week of executive-functions training (subgroup A), or vice versa (subgroup B). Before training (T1), patients performed experimental tasks of decision making (Game of Dice Task, GDT; Probability-Associated Gambling task, PAG-60 task) and of ratio processing as well as a neuropsychological background assessment. Experimental tasks were also administered after the first (T2) and the second (T3) training week.

RESULTS: The numerical training and the training of executive functions had a differential effect on experimental tasks of ratio processing. Only the numerical training proved to be effective. The effects of the two training types on decision making under risk were less clear-cut. While no changes over time were observed in the GDT, performance on the PAG-60 task improved in both training subgroups. These improvements were apparent in one subgroup after a period of executive-functions training, in the other subgroup after both training weeks. That means, improvements are not attributable to one specific training type.

CONCLUSION: Patients with MCI can profit from a cognitive training on number processing and executive functions. Improvements are reflected in higher ratio processing abilities and more advantageous decisions after training. These results are consistent with assumptions of current cognitive models.