Observational studies have consistently found that people with an active life—mentally, physically and socially—tend to be healthier and have a lower risk of mental decline and dementia as they age. No surprise there. But determining cause and effect is hard. Though researchers try to adjust for this in their studies, it could be that people who are mentally and physically healthy are better able to stay active.

A few years ago, one of the biggest and best randomized trials (called ACTIVE), sponsored by the National Institute of Aging, found that five weeks of a cognitive-training program helped older adults boost specific memory and problem-solving skills. The improvements were limited to the abilities trained, but did persist for five years, albeit modestly.

A 2011 Cochrane review of 36 studies found that people with mild cognitive impairment who undertook memory training, mostly group sessions with teachers, improved specific skills, but no more than people who were mentally active in other ways, such as those taking educational classes.

Despite some promising leads, as well as lots of wishful thinking and sales pitches for various programs, the research remains in its early stages.

Playing mind games

Many experts believe that simply doing activities that challenge your cognitive capabilities can help keep you sharp. There’s little doubt that learning a foreign language, playing bridge or chess or solving puzzles (like Sudoku) is better for your brain than staring mindlessly at the TV. Several studies have found that even video action games can improve certain types of memory and other cognitive skills.

Other research suggests that commercial brain-training programs—often computer-based—target key cognitive skills better than, say, puzzles or classwork. These range from game-like products such as Nintendo’s Brain Age to expensive software such as Posit Science’s Brain Fitness Program.

Proving that mental workouts produce significant cognitive benefits in older people is difficult, largely because so many variables are involved. It’s much easier to do long-term clinical trials on drugs for dementia, for example (which, by the way, have not proven to be very effective).

And even when studies on the formal programs—usually sponsored by the companies that market them—find short-term improvements in some kinds of mental performance, so far no one knows if these translate into less overall cognitive decline long-term or a reduced risk of dementia.

One difference between “natural” training (puzzles, games, learning new skills) and formal programs is that the former are complex tasks using everything from memory to visual attention, while formal programs tend to segregate the different tasks and skills. Formal programs may allow you to improve highly specific mental skills more easily, but you may not retain them as well as you would from a more natural process.

Even when you benefit from one kind of training, there may be no carryover to other kinds of mental endeavors. For example, doing crossword puzzles, no matter how expert you become, may not help you remember names or balance your checkbook. That is, working on a brain-fitness program may not provide benefits beyond the particular skills learned.

What’s more, people who start out at high levels may profit more from the training. Those who already have cognitive problems may not benefit or may simply become discouraged. And, of course, we all know of people who developed Alzheimer’s or other forms of dementia who were highly educated and mentally active.

Plenty of reasons to flex your brain power

Even if it doesn’t reduce the risk of dementia, staying mentally active may delay its onset or slow its progression. Stimulating your brain can also enrich your life, banish boredom, help prevent or treat depression and be a way to make new friends.

You don’t need to invest in special games or training programs. Just do something challenging that you enjoy, so you’ll keep at it. You may find formal brain-training programs repetitive and boring, similar to being forced to run on a treadmill when you’d rather be hiking in the woods. Learning a new skill, such as a foreign language; taking classes in art history; playing strategic board or card games or doing volunteer work can be rewarding and fun. These activities can also provide a sense of accomplishment.

If such endeavors confer long-term mental benefits that stave off cognitive decline as well, so much the better.

Other steps to keep in mind: Physical exercise, controlling blood pressure and cholesterol, maintaining a healthy weight, preventing/controlling diabetes, treating depression, drinking alcohol in moderation (if at all) and having a heart-healthy diet are all good bets for brain health. In general, what’s good for your cardiovascular system is good for your brain.