1. It weighs 3lbs and consists mainly of fats and water - but it shrinks as you get older. At the age of 18, we each have 100 billion brain cells (neurons). We lose around 50,000 a day, so that by the age of 80 our brains have shrunk and weigh 10 per cent less.
2. On a day when you are less active, your brain will consume as much as 40 per cent of all the calories you eat and think an estimated 60,000 thoughts.*
3. Alzheimer's disease is characterised by the growth of amyeloid plaques, which put pressure on brain cells, causing them to die.
4. The majority of brain development occurs between the ages of 1 and 3, and there's lots of evidence that a loving and stimulating home environment can boost it.
5. The brain's cortex (or 'grey' matter), contains millions of nerve cells (neurons) at birth which are not yet connected. One theory is that intelligent people have more connections between brain cells than others. 

* Source: The Alzheimer's Disease Prevention Plan