Great article! but I would caution against the claim that any activities can "strengthen" memory. In all of the psychology courses I've taken in undergrad and graduate school, professors have hammered in the fact that (as far as they know), you cannot strengthen memory.
The article that you've cited (Lambert et al., 2019) states that certain activities can help "maintain" healthy brain function during adulthood, including memory, but it doesn't say anything about improving memory. It does mention that certain targeted practices can help improve memory function during early development (i.e., childhood), and they do mention some studies on mice. They also mention that some exercises can help strengthen concentration and high-level processing during adulthood- just not memory.