As we get older, it is no secret that our brain function declines. Staying mentally active can help keep your brain sharp. There are hundreds brain-training apps claim to put the improve cognitive function, but do they really work?

The research is mixed. While some studies have failed to find a link between brain training and improved cognitive functioning, other research has found the opposite.

Research presented at the 2016 Alzheimer's Association International Conference found that older adults who took part in ten 1-hour brain training sessions over a 5-week period were 48 percent less likely to develop cognitive decline or dementia over 10 years. That has led to more interest in brain training apps.

While there is not enough research to determine if brain trainers actually work,  they can’t really harm us, and they can actually be fun. One researcher says you might improve your memory enough to beat the game, but that doesn’t mean you will stop losing your car keys.

Here are a few of the top brain trainers: Memory Trainer, Lumosity, Fit Brains, Sudoku, CogniFit, Peak, Brain Fitness Pro and Eidetic.  They each emphasize something different, so check them out to see which is best for you.