As someone who works in dementia research (...), I can't help but notice the total absence of any well defined target for the challenge, which makes it, for a goal-oriented objective process, a poor choice.

"If Dementia wins the vote, the challenge for Longitude Prize 2014 will be to develop intelligent, yet affordable technologies that revolutionise care for people with dementia enabling them to live truly independent lives."

This reflects the fact that there's not an obvious solution to the dementia problem - yes, there are good big picture targets like this, I'm not sure how well this translates into day-to-day operations.

Beyond this, should we be focussing resources/time/money on conditions which, fundamentally, are a byproduct of a high quality of life for a minority of the worlds population, or should we, perhaps, be focussing on ensuring clean drinking water for everyone, or developing antibiotics. I feel like dementia is somewhat incongruous with the other problems presented, but I suspect it might do well because it's so prevalent in the lives of the specific population voting for this.