If you choose to join this study, you will come in for a screening visit to make sure that you are eligible to participate. During this visit, you will have an MRI scan taken of your brain and do some cognitive testing. If you are eligible to continue, you will get a random assignment (like drawing numbers from a hat) to 1 of 3 brain training groups. Your group assignment might be:

• High-frequency puzzles: If you are in this group, you will do crossword puzzles provided by the study team 4 times per week. OR
• Low-frequency puzzles: If you are in this group, you will do 1 crossword puzzle provided by the study team each week. OR
• Health education: If you are in this group, you will get a book that discusses how health conditions and lifestyle can affect health. The study team will give your reading assignments from this book during the study.

This study lasts for about 78 weeks (1.5 years). Your assigned brain training will last for 12 weeks. After the 12 weeks are done, we will schedule you to come in for follow-up visits to see how you are doing and to do some cognitive testing. During the time you come in for follow-up visits, you will have some periodic "booster sessions" of brain training. These booster sessions will be similar to your assigned brain training. To participate, you will need to have a study partner who is close to you and who can speak with the study team about how you are doing while you are taking part in the study.