Neuroscience: Memory treatment is possible, when impairment is not disastrous.

This is a media release, obviously, but I know from experience that its basic thesis is true, and that it can work with seniors of advanced age:

Increasing scientific evidence shows that actively participating in appropriately designed brain fitness workouts aids mental agility. Scientific Brain Training PRO exercises were developed by a team of neurologists, cognitive psychologists and educational scientists to offer unique and challenging configurations that target various areas of cognitive impairment. The Memory Treatment Program is the latest program to take advantage of the SBT PRO online platform features of clinician-managed patient accounts and consistent patient records to meet the need of professionals who treat patients with cognitive impairment.

One caution: Success is greatly increased if the seniors' relatives actually care, visit, phone, and write, send cards, and bring mementoes. People are motivated to try harder when they think others care too - team spirit and all that.