Causes of dementia
The most common cause of dementia in older adults is Alzheimer's disease. A German doctor in 1906, Dr Alois Alzheimer, first described the disease. He described characteristic changes in the brain tissue of a woman who had died of an unusual mental illness.Today still, the exact cause of Alzheimer's disease is unknown. However, we know much more about what happens in the brain and a number of risk factors for the illness have also been identified. The disease process causes structural changes of brain matter and, associated with this, certain brain chemicals (neurotransmitters) also change.
In Alzheimer's disease the disease process starts in the temporal lobes and from there it spreads to involve other brain areas. The areas involved in basic processing of sensory and motor functions are usually spared, as well as some of the nuclei in the deep brain matter. The cerebellum (or small brain) is also comparatively spared.
Brain structure is disrupted by the formation of neurofibrillary tangles (NFT) and neuritic plaques (NP). Formation of NFT and NP causes disruption of the integrity of brain cells and leads to brain cell death.
The loss of brain cells leads to neurotransmitter deficits, especially the loss of acetylcholine (ACh). Medication that increases the level of ACh in the brain leads to an improvement of memory in Alzheimer's disease.
