It’s hard to believe another year has gone by! When it comes to our health, it seems like some things change quickly, and sometimes progress proceeds at a snail’s pace.

Here are some of 2011′s top stories.

A new source of stem cells

Last year’s stem cell breakthrough was creating pluripotent stem (iPS) cells from human skin, but this year the latest breakthrough comes from cloning. Researchers at the New York Stem Cell Foundation used a modified version of a cloning technique known as somatic cell nuclear transfer (SCNT) to create human stem cells. In this trial, researchers combined the DNA of an adult human cell with the genetic material of an egg. Keeping the egg cell’s DNA — rather than replacing it — allowed researchers to create an egg capable of dividing to make new stem cells.

However, the research is still in the early stages, and the problem is the cells have one extra chromosome. In the future, experts hope to correct this abnormality. (See Time Magazine for more information.)

First face transplants performed in North America

Once a creepy movie premise (remember Face Off ?), face transplant surgery offers new hope to patients disfigured by serious accident or injury. Only a handful of people worldwide have had this extensive and controversial procedure, and this summer the first transplant was performed in the U.S. on Dallas Wiens, who suffered severe electrical burns.

Just a couple of months later, another widely publicized case emerged — that of Charla Nash, who was mauled by a friend’s pet chimpanzee. News reports around the world followed the progress of these remarkable people — both are now doing well.

While the procedure hasn’t yet been performed in Canada, doctors at the University Health Network and the Hospital for Sick Children in Toronto are getting ready to offer the surgery sometime in 2012, according to a Globe and Mail report.

Alzheimer’s disease starts long before symptoms

We wish we could report a cure or a sure-fire preventative, but sometimes a change in approach can be a big leap forward. The bad news is doctors discovered the disease process starts earlier than previously thought. Growing evidence shows that changes are happening in the brain long before symptoms of dementia appear.

The good news? With this new definition experts can look for better ways diagnose and treat the disease in its earlier stages when treatment could make the most difference.

In other Alzheimer’s news, experts also found a link between diabetes and the risk of developing Alzheimer’s, and researchers are working an Alzheimer’s blood test they say can diagnose the disease in its early stages.