My Ma had a close friend who had memory loss before she did and the son sent mum a lovely letter giving a couple of paragraphs of news and just saying that x had been unwell and was too frail at the moment to write and so they were doing the letters together as she didn't want to lose touch. I thought it was a really nice idea - it kept the links between the two friends and left the door open for future communication and preserved dignity too. We continued to correspond through the son