[tgv]

I did check [1]. That's where the differences between the four groups can be found. There are 12 effect sizes, only two or three medium (≥0.5). Some of the others are even negative. It's pretty suspicious that the type of training matters so much. It's as if it's training to the test.

But if this is what it is, then by all means, do cognitive training for the elderly: it can't do any harm. But there doesn't seem to be any point in further research.