Perhaps try working memory training software of the type that Suzanne Jaeggi used in her studies. The software is called Brain Workshop. It is free. Note the s

Perhaps try working memory training software of the type that Suzanne Jaeggi used in her studies. The software is called Brain Workshop. It is free. Note the science on this is messy. Jaeggi's paper suggested transfer to fluid intelligence, then another paper questioned that, then she wrote a better designed follow up, then another paper questioned that. Anecdotally I think it worked for me. I personally think the difference in study outcomes may have been driven by differences in how diligently study participants stuck to the regime, or perhaps even how well they understood what they were supposed to do. A second recommendation is to read John Medina's book 'Brain Rules for ageing well' which has lots of tips for combating cognitive decline.