Some 2.3 million of U.S. adults over 65 – more than 4% – have a diagnose of dementia. But even without a diagnosis, a certain amount of cognitive decline is normal as age sets in.

And whether it's due to fear of cognitive decline or noticing lapses in cognition when we are stressed, many of us have had moments when we thought we could use an extra cognitive boost.

The good news is research has shown that people can make changes throughout adulthood that can help prevent or delay cognitive decline and even reduce their risk of dementia. These include quitting smoking and properly managing blood pressure.

In addition to these lifestyle changes, many people are turning to brain-training games, which claim to optimize your brain's efficiency and capacity at any age.

The makers of brain-training apps and games claim their products can do everything from staving off cognitive decline to improving your IQ.

But so far these claims have been met with mixed evidence.

We are cognitive neuroscientists who focus on brain health across the adult lifespan. We study how the brain informs cognition and the ways we can use brain imaging to understand cognitive and brain-training interventions. We aim to understand how our brains change naturally over time as well as what we can do about it.

Ongoing research shows what actually happens to the brain when it is engaged in new learning, offering a window into how people can sustain their brain health and how brain-training games can play a role. We believe these studies offer some strategies to train your brain the right way.

Brain training fact vs. fiction

Brain training a set of tasks, often computerized, based on well-known tests to measure a type of cognition, but in a gamified manner.

Most brain-training games were designed to help participants master one or more specific skills. One example is a game that shows you a letter and number combination, where sometimes you must quickly identify whether the letter is even or odd, while other times you must switch to deciding whether the letter is a consonant or vowel. The game may increase in difficulty by requiring you to accomplish the task within a set time limit.

Such games are designed to require a high level of attention, fast processing speed and a flexible mind to alternate between the rules, known as executive functioning.

But it turns out that the specific skills learned in these games often do not translate to more general, real-world applications. Whether brain games meet their end goal of lasting cognitive improvement across a number of areas is still highly debated among psychologists. To make such claims requires rigorous evidence that playing a specific game improves cognitive or brain performance.

In 2016, in fact, the Federal Trade Commission issued a US$50 million penalty to one of the most popular brain-training games at the time, Lumosity, for misleading consumers into thinking that they could achieve higher levels of mental performance at work or at school and prevent or delay cognitive decline by using its product.

If improving on a brain game helps the player get better only at that or highly similar games, maybe game developers need a different approach.

Put some challenge into it

In a study dubbed the Synapse Project, in which one of us, Ian McDonough, helped assess the final outcomes, one group of participants were tasked with engaging in a new activity with which they had little experience. They were assigned to either digital photography or quilting.

Though these activities were not games, they were meant to be engaging, challenging and done in a social environment.

Another group was assigned activities that involved little active learning, such as engaging in themed activities related to travel or cooking, or more solitary activities such as solving crossword puzzles, listening to music or watching classic movies. These groups met for 15 hours a week over 14 weeks. All participants were tested at the beginning and end of the study on various cognitive abilities.

Those assigned to the new, challenging activities showed significant gains in their memory, processing speed and reasoning abilities relative to those assigned to the less challenging activities.

None of the participants were directly trained on these cognitive tests, which means that the challenging activities enhanced skills that transferred to new situations, such as remembering a list of words or solving abstract problems.

Brain scans of participants showed that over the course of the study, those engaged in the more challenging activities increased their neural efficiency. In other words, their brains didn't have to work as hard to solve problems or recall information.

The study also showed that the more time participants spent on their projects, the bigger their brain gains and the better their memory was at the end of the 14 weeks.

One difference between the types of activities engaged in the Synapse Project and traditional brain training is whether activities are done in a group or alone.

Although other studies have found a benefit to social interaction, the Synapse Project found no difference between the social and solitary activities in the low-challenge group.

So, challenge rather than the social components seems to be the driver of maintaining cognitive and brain health.

What you can do to maintain a healthy brain

You might be thinking it's time to take up digital photography or quilting. But in the end, it's not about those specific tasks. What matters most is that you challenge yourself, which often comes naturally when doing something new.

The new learning that often is accompanied by a sense of effort – and sometimes frustration – requires accessing the resources in the frontal lobe, which manages thinking and judgment, and the parietal lobe, which processes attention and combines different sensory inputs.

These regions constantly talk to each other to keep the mind adaptable in all kinds of situations and prevent the brain from going into "habit mode."

Where does this leave us? Well, on the one hand, games touted as "training your brain" may not be the best solution compared with other routes to improving cognition.

Ironically, you might already be training your brain by playing effortful games that are not marketed as "brain training." For example, games such as Tetris or real-time strategy games such as Rise of Nations have shown improvements in players' cognition.

Research has even shown that playing Super Mario 64 can result in increases in brain volume in regions such as the hippocampus, the memory center of the brain.

While little evidence suggests that any brain-training game or program globally improves cognition, some may improve specific aspects of it. As with other activities, challenge is key.

If you're a word person, try a numbers-based game. If you love math, consider a word game or puzzle. Choosing a task that makes you feel uncomfortable gives you the best shot at maintaining and even improving your cognition.

Once you start feeling a sense of ease and familiarity, that's a sign that it's time to switch tasks, change the game or at least add some challenge by advancing to a new level of difficulty that feels just beyond your reach.