Forget where you left your keys this morning? Or maybe you left your umbrella in the office before a rainy evening. Don't worry, it's probably not a sign of Alzheimer's — everyone is a little forgetful now and then. But the prevalence of Alzheimer's and other types of dementia, which slowly deteriorate the brain's capacity to make new memories, retrieve older ones and perform other mental and physical tasks, is on the rise as the baby boomer generation hits retirement age. A 2007 Alzheimer's Association report estimated that more than 5 million Americans were currently living with the disease and that that total could reach 16 million by 2050. Scientists are still trying to unravel the many mysteries of the brain — how our brain processes information, how memory works, how the brain ages and how diseases like Alzheimer's develop — so that we better understand our own minds and how to keep them healthy. But while there is still a lot to learn about our noggins, several studies have worked out a few ways to help keep your thinking organ in shape, now and as you age. 1. Eat Your Brain Food You are what you eat, or at least your brain is. A diet of junk food can junk up your brain, as things like trans fats and saturated fats, common in heavily processed foods, can negatively affect the brain's synapses. Synapses connect the brains neurons and are important to learning and memory. On the other hand, a balanced diet rich in omega-3 fatty acids — found in salmon, walnuts and kiwi fruit — can give the synapses a boost and help fight against mental disorders from depression to dementia. 2. Hit the Gym Giving the rest of your body a workout can also improve your memory, make you think more clearly and decrease the risk of developing cognitive diseases, several studies have suggested. Because exercise is a mild stressor to your body, eating up the precious energy needed by the brain, it triggers the release of chemicals called growth factors that make the brain's neurons stronger and healthier. Half an hour every other day will do it, experts say. And don't forget to stretch: Stretching can help reduce stress, which can impact the memory centers of your brain. 3. Mind Benders Give your brain a workout, too, with brainteasers, crossword puzzles and memory games — studies have shown that using these tools to stay mentally active can reduce the risks of developing dementia by building and maintaining a reserve of stimulation in your brain. Even following the current political campaign can provide a boost to the systems that control attention and learning that are hard-wired into the brain. 4. Memory tricks Keeping information stored in your memory banks and retaining that memory with age may also be a simple matter of mind control. For example, confidence in your cognitive abilities could actually affect how well your memory functions, particularly for the elderly. Because some older adults tend to blame memory lapses on age, regardless of whether or not that is the cause, they can keep themselves from even really trying to remember. Prediction can also enhance memory: If you have a good idea of the information you'll need to recall later, you're more likely to remember it. 5. Give it a Rest Sleep gives your brain a chance to replay the memories of the day and consolidate them for long-term storage. One study suggested that the brain can do its reviewing much faster when you're asleep than when you're wide awake — so no more all-nighters, students. A 90-minute mid-afternoon nap can even help solidify long-term memories, such as events or skills you are trying to master. Siesta anyone? Of course, none of these mind-enhancing tips is fool-proof. Some studies have suggested that developing Alzheimer's and other types of dementia is partly a matter of genetics. One such study, presented in July at the Alzheimer's Association's International Conference on Alzheimer's Disease, hinted at a connection between mothers who develop Alzheimer's and the chances their children will become afflicted in old age. Another suggests that having a specific pattern of proteins is a risk factor for the debilitating disease. But for now, no one can predict exactly who will or won't develop dementia. While scientists work on better indicators and cures, doing your own part to keep your body and brain healthy is probably the best you can do.