Alzheimer's disease

An irreversible, progressive disorder in which brain cells (neurons) deteriorate, resulting in the loss of cognitive function (primarily memory, judgement and reasoning), movement coordination.

• Predominantly affects: cerebral cortex, hippocampus
• Neuritic plaques: A protein (beta amyloid) occupies the centre of the plaques. Surrounding the protein are fragments of deteriorating neurons (especially those producing acetylcholine which is necessary for memory and learning
• Neurofibrillary tangles (NFTs): Twisted remnants of a protein called tau, which is found inside the brain cells and is essential for maintaining proper cell structure and function. An abnormality in the tauprotein disrupts normal cell activity. The number and distribution of the plaques and tangles appear to contribute to the problems with memory and other mental abilities. There also are lower levels of some of the chemicals  (acetycholine) in thebrain that carry messages back and forth between the nerve cells

• Executive functions
• Organising a volitional response to environmental contingencies