Eventually, we’ll reach a point where keeping our bodies alive will be simple science. Drugs and surgical modifications, possibly through the use of vat-grown replacement organs, will keep us chugging as long as we are able. There might be a problem, though, it if turns out the human mind simply isn’t capable of containing multiple lifetimes of memories. Alzheimer's might be an illness that strikes many of us as we age, but our current average life expectancies are already double just a century ago. We continue ways to heal and maintain our bodies, but our minds are chemical databases. Alzheimer cures might buy us another decade, but it will require better approaches or it may turn out impossible to maintain mental youth without severe solutions such as memory scrubbing, invasive surgery or physical memory grafted into our brains. So what happens when you hit 147 in 2338 and you look like someone 47 in 2013? Your body is still in great condition, but your mind is worn and scarred from a century and a half of whatever is going on in the future? With the probability of a few billion more living on and around the Earth, I suspect suicide could turn into an entertainment opportunity.