Diet
Diet may be a modifiable risk factor for the development of Alzheimers disease. The Mediterranean diet, and the DASH diet are both associated with less cognitive decline. A different approach has been to incorporate elements of both of these diets into one known as the MIND diet. Studies of individual dietary components, minerals and supplements are conflicting as to whether they prevent AD or cognitive decline. Prognosis
The early stages of Alzheimers disease are difficult to diagnose. A definitive diagnosis is usually made once cognitive impairment compromises daily living activities, although the person may still be living independently. The symptoms will progress from mild cognitive problems, such as memory loss through increasing stages of cognitive and non-cognitive disturbances, eliminating any possibility of independent living, especially in the late stages of the disease.Life expectancy of people with Alzheimers disease is reduced. The normal life expectancy for 60 to 70 years old is 23 to 15 years; for 90 years old it is 4.5 years. Following Alzheimers disease diagnosis it ranges from 7 to 10 years for those in their 60s and early 70s (a loss of 13 to 8 years), to only about 3 years or less (a loss of 1.5 years) for those in their 90s.Fewer than 3% of people live more than fourteen years. Disease features significantly associated with reduced survival are an increased severity of cognitive impairment, decreased functional level, history of falls, and disturbances in the neurological examination.
This disrupts the work of the brain cells affected and triggers a toxic cascade, ultimately leading to cell death and later brain shrinkage.Alzheimers disease is believed to occur when abnormal amounts of amyloid beta (Aβ), accumulating extracellularly as amyloid plaques and tau proteins, or intracellularly as neurofibrillary tangles, form in the brain, affecting neuronal functioning and connectivity, resulting in a progressive loss of brain function. This altered protein clearance ability is age-related, regulated by brain cholesterol, and associated with other neurodegenerative diseases.Advances in brain imaging techniques allow researchers to see the development and spread of abnormal amyloid and tau proteins in the living brain, as well as changes in brain structure and function. Beta-amyloid is a fragment of a larger protein. When these fragments cluster together, a toxic effect appears on neurons  and disrupt cell-to-cell communication. Larger deposits called amyloid plaques are thus further formed.Tau proteins are responsible in neurons internal support and transport system to carry nutrients and other essential materials. In Alzheimers disease, the shape of tau proteins is altered and thus organize themselves into structures called neurofibrillary tangles. The tangles disrupt the transport system and are toxic to cells. The cause for most Alzheimers cases is still mostly unknown, except for 1–2% of cases where deterministic genetic differences have been identified.