Great question Mattias. There are some studies comparing neurofeedback effects across young and old age groups, and several of those do not find major differences between them. Here is one example if you’re interested: https://www.sciencedirect.com/science/article/pii/S1388245713006949

It‘ll be interesting to watch how this work develops over the next few years because neurofeedback could be a useful tool for assisting with natural age-related cognitive decline.