The field of cognitive training has moved way beyond preliminary promise.
Here's a meta-analysis of 97 published randomized controlled trials, showing reliable improvements in cognitive function and transfer to real-world function [1]
Here's an NIH-funded study of more then 2,800 older adults followed for 10 years showing that speed-of-processing training reduces the risk of dementia by 29% [2]
Disclosure: I work at a cognitive training company.
From [2], above: (hazard ratio [HR] 0.71, 95% confidence interval [CI] 0.50–0.998, P = .049)
Yowzers -- just squeaked by on that one, didn't they. Given the unknowns around dropouts, I would be frankly astonished if these results stood up. It mainly looks like the "speed" category dubiously "benefited" from a higher death rate; the ~20 excess deaths in that subset can neatly account for ~2 additional cases that drives significance to random-chance levels again.
In addition, the meta-analysis seems to indicate that only memory-based interventions work, while the individual study linked showed differently. Hopefully as pre-registration becomes mandatory it should become clearer how many of these studies were abandoned because of null results.
From [1] (the meta-analysis), "Working memory interventions proved most effective (g = 0.479), though memory, processing speed, and multi-domain interventions also significantly improved cognition."
From [2] (the crash results), deaths and drop-outs were handled by adjusting crash rates to total person-year exposure times. In this study as a whole, non-completion rates were not significantly different across groups.
Yowzers -- just squeaked by on that one, didn't they. Given the unknowns around dropouts, I would be frankly astonished if these results stood up. It mainly looks like the "speed" category dubiously "benefited" from a higher death rate; the ~20 excess deaths in that subset can neatly account for ~2 additional cases that drives significance to random-chance levels again.
In addition, the meta-analysis seems to indicate that only memory-based interventions work, while the individual study linked showed differently. Hopefully as pre-registration becomes mandatory it should become clearer how many of these studies were abandoned because of null results.