Dementia is caused by problems in the way the brain works. The brain is made of billions of brain cells or 'neurones', through which electrical signals pass. Normally these cells signal to each other through narrow gaps (synapses) with the help of chemicals called 'neurotransmitters'.
Dementia is caused by neurones not working properly or dying. This often changes the levels of different neurotransmitters, which affect the function of the brain. The most common cause of dementia is Alzheimer's disease, which destroys certain brain cells and alters the transmission of signals through the brain - particularly memory - and this can lead to depression.
Drug treatment of dementia usually aims to improve memory and concentration, reduce psychiatric problems. The memory difficulties seen in Alzheimer's disease can be relieved for a short time with drugs that prevent the breakdown of acetylcholine in the brain. These drugs are called 'cholinesterase inhibitors' and are thought to work by increasing the levels of acetylcholine in the synapses. They can improve memory, as well as slow down some of the changes in personality and mood. Depression cause by Alzheimer�s can also be relieved by anti-depressants.