Can games prevent cognitive decline? Several companies think they might. Posit Science sells the Brain Fitness Program for PCs for $395, and there's Brain Age for Nintendo's (NTDOY) DS handheld system (about $20 for the game, $130 for the device). The newest entrant is Dakim BrainFitness, which sells [m]Power Cognitive Fitness System. It's sold as a computer with 120 different games, each with five skill levels. In one, players watch scenes from old movies, then recall such details as characters' names and lines. Another, The Violin, uses recordings of famous classical musicians to engage players in a tutorial on the instrument. The unit, which sells well to nursing homes, is costly, at $2,295, plus $19.99 per month for updates. Dakim is working on next-generation systems that can track a player's cognitive function over time and report changes to family members or doctors. That could help detect small strokes or early signs of dementia.