Injuries , illnesses and other diseases that you may inherit from your parents or grandparents can damage your brain. Disorders that destroy brain cells are very serious because the body cannot replace lost cells.

A stroke occurs when the brain cells do not get enough oxygen , which is transported throughout your body by blood . If this happens the brain can no longer work in the damaged area . Many stroke victims are not able to use a certain side of their body and, very often, they lose the ability to speak clearly. Strokes are often caused by high blood pressure or when arteries become harder. Some stroke victims die, others recover partly.

Brain tumours are caused by the rapid growth of cells. Such fast-growing cells destroy healthy ones. As they grow they create pressure and may damage other areas of the brain. Sometimes tumours can be removed by operations or with drugs.

Many diseases that are caused by bacteria or viruses can also do damage to the human brain. One of the most common illnesses is meningitis, a disease that affects the membranes that cover the brain and the spinal cord.

Sometimes the brain of an unborn baby does not develop the way it should. In Down's syndrome there is an extra chromosome that causes mental disorder. In other cases genetic errors cause brain damage in later life. Huntington's disease, for example, occurs mostly during middle age. It leads to jerky movements of the body.

Alzheimer's disease often occurs after the age of 60. Many victims suffer from a loss of memory, and they often cannot care for themselves.

Today, modern medicine has ways and methods of looking into the human brain. The EEG ( electroencephalogram ) records the activity in the brain. Computed tomography makes pictures by sending many X-rays through the brain. Magnetic resonance imaging (MRI) uses powerful magnets to show how atoms in your brain change.