On the homepage for the brain-training game NeuroNation, there's a spinning, high-tech science-y brain with blinking lights. It says, "Your potential is infinite."

Over at Lumosity, another popular brain game, there's talk of cognitive abilities, legions of researchers and establishing your baseline. The games sound so promising and reference how they are "scientifically proven."

Researchers have been divided over whether brain-training games really work. Some studies have found benefits while others have shown none. That's why a team of seven scientists performed an extensive evaluation of more than 130 studies in scientific literature about brain training and other cognitive games. They found that many of the studies had flaws in the way they were designed.

The University of Aberdeen released its findings from a 15-year-long study that involved 498 participants who were born in 1936 and living independently in Scotland. Researchers determined that no matter how many brain-stimulating activities participants did, they were all destined to experience mental decline as they aged. The caveat is that those who regularly performed brain games throughout their young-adult and middle-aged years began their mental decline later in life and reached a much higher peak compared to those who didn't perform these activities.

Some other studies, however, showed that brain games do help people get better at one specific task, but there's less evidence that brain training can help you get better at related tasks. The research was published in the journal Psychological Science in the Public Interest.

On the flip side, a new study led by University of California, Irvine, researchers finds that online brain games enable people in their 70s and 80s to multitask cognitively as well as people who are 50 years younger.

"The brain is not a muscle, but like our bodies, if we work out and train it, we can improve our mental performance," said lead author Mark Steyvers, a UCI professor of cognitive sciences, in a statement. "We discovered that people in the upper age ranges who completed specific training tasks were able to beef up their brain's ability to switch between tasks in the game at a level similar to untrained 20- and 30-year-olds."

Similarly, a study published in the journal Alzheimer's & Dementia finds that playing speed decision-making games seems to lower dementia risk. Researchers analyzed the results of a study which followed 1,220 people over 10 years. Participants were divided into four groups. One group was taught memory tricks, one group learned reasoning skills, and one group played a speed-training game on the computer. The last group of people weren’t given anything. Only 5.9 percent of the people in the speed-training group developed dementia; in the other three groups, the figure was around 10 percent.

The placebo effect

A study published in the journal Proceedings of the National Academy of Sciences found that some of the alleged benefits of brain games may be due to placebo effects.

Researchers at George Mason University in Fairfax, Virginia, recruited 50 participants for the study using two different fliers, reports HealthDay. One flier specifically mentioned a "Brain Training & Cognitive Enhancement" study and noted that "numerous studies have shown that working memory training can increase fluid intelligence." The other flier didn't mention brain training or any benefits, and instead just offered research credits for taking part in an unspecified study.

All of the study participants took an IQ test, then did an hour of brain training — not enough, the researchers point out, to likely boost anyone's intelligence. The next day, the participants took another IQ test. Those who were told of brain-training benefits had a 5-10 point boost in their IQ score, while those who heard nothing of the benefits tested about the same as they did before the training.

"We don't believe this is because they actually got smarter after one hour of training," lead researcher Cyrus Foroughi said.

4 games to try for fun

So the benefits of training your brain might be all in your head. But if the placebo effect works for you, who cares? They're still fun (and better than watching TV). Here are four cognitive training games if you want to give brain boosting a shot.

Lumosity

Lumosity migration game Lumosity games include quickly spotting the bird migrating in the wrong direction. (Photo: Lumosity)

Around since 2005, Lumosity is the granddaddy of the bunch. The games change each session and are geared toward boosting memory, attention, problem solving, processing speed or flexibility of thinking. Games are timed and range from which bird in a flock is flying in the wrong direction to speed packing a suitcase so everything fits. (Basic plan is free; upgrade is $11.95/month)

NeuroNation

NeuroNation Math is good for your brain. (Photo: NeuroNation)

Called "the gym for your mind," NeuroNation offers more than 60 games. You take an initial evaluation to spell out your goals, and then your games are personalized to fit those goals. Games are designed to improve memory, focus and intelligence. (Initial activities are free, then you pay per set of games.)

Peak

peak app Peak offers encouraging words like, 'Play smart, feel sharp!' (Photo: Peak)

Billed as a combination of neuroscience, technology and fun, Peak is an attractive game that focuses a lot on memory. You get a personalized six-game workout every day that adapts to how well you perform. The newest game added to Peak is called Decoder, which involves a number sequence test. A study conducted by the developers at the University of Cambridge shows that those who played Decoder tested higher in attention and performance than those who played bingo or no games. Right now, Decoder is only available on Apple devices. (Free basic subscription, then $5/month and up)

Elevate

Elevate Elevate games include error avoidance and brevity. (Photo: Elevate)

One fan of this popular app gushes on the Elevate webpage, "I feel like I'm taking a mental multivitamin." The relatively new training program offers nearly three dozen activities working on things like focus, estimation, spelling, agility, memory, pronunciation, precision and clarity. (Free basic, then $5 and up/month)

Editor's note: This story was originally published in June 2016 and has been updated with new information.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

Brain-training games may work, or they may not
In case you want to give brain-training games a shot, here are 4 to try.