According to the National institute on Aging (NIA), Alzheimer’s disease is considered “a major public health problem” affecting millions of older Americans. The NIA is the lead research agency for the National Institutes of Health (NIH).
When healthy people continue to age, their brain changes. Parts of it shrink, communication between neurons is reduced, blood flow is reduced, and plaques and tangles may develop around neurons. These affects may produce a small decline in memory retrieval, complex tax performance, and new memory production. However, if given enough time to complete a task, healthy older adults are usually able to do so.
Why do some people develop dementia and others do not? The answer to this question is not entirely understood. Scientists believe the answer may lie in “cognitive reserve”, also called “reserve capacity.” This term refers to the brain’s ability to function despite disruption from the aging process. Education, occupation, and genetics may improve one’s reserve capacity.
Alzheimer’s disease is the most common neurodegenerative disease and the most common form of dementia.
Characteristics of Alzheimer’s disease
The brain of an Alzheimer’s person contains deceased neurons, amyloid plaques and neurofibrillary tangeles of proteins. The death and disruption of these cells (neurons) causes memory failure, changes in personality, language, and problems carrying out routine activities. It is not known exactly what starts Alzheimer’s disease.
A neurologic exam helps to diagnose the disease, although an autopsy is the only definitive diagnosis.
Predicted survival time for women with Alzheimer’s disease is 5.7 years, for men 4.2 years. However people who are diagnosed at a young age usually survive longer than those diagnosed at an older age.
According to a study at the Rush Institute on Aging by Hebert et al., Alzheimer’s disease is strongly correlated to age. The percentage of those studied who had Alzheimer’s disease was 0.6% for those aged 65-69, 1.0% for those aged 70-75, 2.0% for those aged 75-79, 3.3% for those aged 80-84, and 8.4% for those 85 and older.
Education and Occupation
A study was done at Columbia University on the correlation of Alzheimer’s with education and occupational attainment. The authors suggest that a low level of education may cause or influence Alzheimer’s disease, as “more years of education was associated with a reduced risk of dementia”. The authors hypothesize education may improve cerebral blood flow and provide skills to cope before AD emerges. These skills are also called the “reserve capacity”. When an individual’s reserve capacity falls below a certain threshold, it is believed that dementia may result.
“Education may provide protection or reserve against the clinical manifestation of AD.”
Since an individual normally only spends a fraction of his or her life in school, the study also evaluated occupational attainment in the prevalence of Alzheimer’s. The authors found “lower occupational attainment was associated with a higher risk of dementia.
Early Linguistic Ability
Another study examined the correlation between linguistic ability early in life and Alzheimer’s disease. The Sanders-Brown Center examined the famous Nun Study of the Sisters of Notre Dame, which was a longitudinal study of aging and Alzheimer’s disease. They looked at the grammatical complexity and “idea density” (educational level, vocabulary, and general knowledge) of each nun’s autobiography before she entered the convent, which was at an average age of 22. The nuns’ current cognitive and neuropathologic functions were evaluated as well.
The study found that low “idea density” in early life accounted for 90% of those with Alzheimer’s.
According to the researchers, “A high level of linguistic ability in early life may act as a buffer to cognitive decline by facilitating mnemonic processes for encoding, organizing, and retrieving information.”
In addition to linguistic ability and educational and occupational advancement, the NIA has the following recommendations for brain health:
- The prevention of chronic diseases, such as heart disease and diabetes, by controlling risk factors (a healthy weight, blood pressure and blood sugar monitoring)
- Regular exercise
- Well-balanced diet with fruits, vegetables, fiber, and water
- Intellectually stimulating activities
Scientists are continuing to seek methods of treatment and prevention for Alzheimer’s, including interventions long before symptoms appear. There is no “magic bullet” cure for Alzheimer’s, so scientists are working to develop a variety of treatment options.
Numerous studies are currently being done to manage symptoms and slow or prevent Alzheimer’s.