There is not enough information about the cause (not correlation, but cause) of Alzheimer's Disease to specifically state that any one thing can ever prevent it. However, studies have shown that the onset of Alzheimer's can be delayed by living a healthy, active, social lifestyle. Brain games, or, more importantly, brain engagement may be a factor in that delay. In order to live a healthy life, take the time to inventory all aspects of diet, exercise, social interaction and intellectual activity to ensure that you have a good balance of each.
There are a few resources that may assist you in understanding some of the details. You may try doing some research with the Alzheimer's Association at Alz.org for more information. http://www.webmd.com/alzheimers/guide/preventing-dementia-brain-exercises http://www.alz.org/we_can_help_brain_health_maintain_your_brain.asp