Changes in brain structure characteristic of AD
Alzheimer disease (AD) is neurodegenerative disorder (ND) that most commonly occurs in the elderly (although some people get it as early as age 30) and causes the progressive loss of cognitive abilities, particularly memory and recall, but in the later stages one's sanity and mood may also be detrimentally affected. Many people think that AD is a normal part of ageing but it is not; see while ageing does generally cause slow declines in cognitive function (like over a matter of decades) AD produces significantly faster reductions in cognitive skills (like over a handful of years). It causes the gradual destruction of the cerebral cortex and hippocampus, with a greater preference for the latter structure (that is, it affects the hippocampus more than the cortex). It is the single most common ND in the developed world; followed by Parkinson's disease. It is inevitably fatal, most commonly due to complications of immobility such as pneumonia (lung infection) or pulmonary embolism (blood clot to the lungs, usually the result of a deep vein thrombosis in one's legs).