Recent research into what causes working memory deficits in older adults has found that

The correct answer is older adults have more trouble juggling all of the information in their working memory.

Working memory (WM) refers to a short-term memory storage system that is temporary and has limited capacity. WM temporarily stores information so that we can quickly use or manipulate it. For example, if you are following a recipe from a recipe book, your working memory stores the steps you just read so that you can execute it while your prepare your dish. WM also comes into play when you memorize a list of ten words. Older adults experience working memory deficits because they have trouble juggling all the information in their WM.