Younger people can get aging diseases too – they’re called aging diseases because they have an ‘aging phenotype’ (things go wrong that we’d only expect to happen to old people, like muscle weakness, heart failure, loss of brain cells, etc), rather than that they affect old people – though they are more common in the elderly.
Some of the more well-known diseases, like parkinsons and alzheimers, usually affect older people of 60years old or more, but there are certain types of these diseases that can affect younger people. Alzheimers can start as young as 30, while some of the nastier cases of Parkinsons can start affecting people in their 40s (Michael J Fox started getting his symptoms very young).
Other aging diseases include mitochondrial diseases, which not many people have heard of – its when the mitochondria in some of your cells stop making energy, and these cells can’t do their jobs properly any more. The symptoms of these diseases are really diverse, depending on which cell types are affected, but most commonly include muscle weakness, learning difficulties, liver and kidney problems, or heart failure. The symptoms of these diseases tend to get worse as the patients age, but some types (like Leighs disease) affect children very badly – sometimes even new-born babies. 🙁
We’re working very hard on trying to minimise the affects for anyone who suffers from these aging diseases though – its a real priority in current research to find ways for people to age healthily 🙂