NIH - Medical Encyclopedia Alzheimer's Disease

"Alzheimer's disease (AD), one form of dementia, is a progressive, degenerative brain disease. It affects memory, thinking, and behavior. Memory impairment is a necessary feature for the diagnosis of this or any type of dementia. Change in one of the following areas must also be present: language, decision-making ability, judgment, attention, and other areas of mental function and personality. The rate of progression is different for each person. If AD develops rapidly, it is likely to continue to progress rapidly. If it has been slow to progress, it will likely continue on a slow course. There are two types of AD -- early onset and late onset. In early onset AD, symptoms first appear before age 60. Early onset AD is much less common, accounting for only 5-10% of cases. However, it tends to progress rapidly. The brain tissue shows "neurofibrillary tangles" (twisted fragments of protein within nerve cells that clog up the cell), "neuritic plaques" (abnormal clusters of dead and dying nerve cells, other brain cells, and protein), and "senile plaques" (areas where products of dying nerve cells have accumulated around protein). Although these changes occur to some extent in all brains with age, there are many more of them in the brains of people with AD."

Education and Alzheimer disease without dementia: support for the cognitive reserve hypothesis. (Neurology. 2007)

"CONCLUSIONS: Regardless of the neuropathologic criteria used, education is predictive of dementia status among individuals with neuropathologic Alzheimer disease. These results support the theory that individuals with greater cognitive reserve, as reflected in years of education, are better able to cope with AD brain pathology without observable deficits in cognition."

Nutritional factors, cognitive decline, and dementia. (Brain Res Bull. 2006)

"Nutritional factors and nutritional deficiencies have been repeatedly associated with cognitive impairment. … Deficiencies of several B vitamins have been associated with cognitive dysfunction in many observational studies. More recently, deficiencies of folate (B(9)) and cobalamine (B(12)) have been studied in relation to hyperhomocysteinemia as potential determinants of cognitive impairment, dementia, and Alzheimer's disease (AD). A small number of studies assessed the association between intake of macronutrients and cognitive function or dementia. Among the others, the intake of fatty acids and cholesterol has received particular attention. Although the results are not always consistent, most studies have reported a protective role of dietary intakes of poly- and mono-unsaturated fatty acids against cognitive decline and AD."

Exercise Is Associated with Reduced Risk for Incident Dementia among Persons 65 Years of Age and Older (Annals of Internal Medicine 2006)

"Conclusion: These results suggest that regular exercise is associated with a delay in onset of dementia and Alzheimer disease, further supporting its value for elderly persons."