Non-genetic risk factors include a range of diverse factors, including :

• Age
• Food and Diet,
• Consumption of Metals,
• Weight, Blood Pressure, Heart Disease and Cholesterol,
• Smoking,
• Diabetes,
• High Homocysteine Levels,
• Head Trauma History,
• Education Level,
• Early Life Experiences, and,
• Hormone Replacement Therapy (HRT).

Each of these risk factors is discussed below.

Age

As a person ages, their brain undergoes a number of changes :

• Some nerve cells, called neurons, in various regions of the brain die, although the neurons most important to learning usually live on.
• Some neurons, and the fibers that connect them to other neurons, shrink and degenerate. This tends to especially occur areas of the brain that are important to learning, memory, planning, problem solving, and other complex mental activities.
• Twisted fibers, called tangles, develop within neurons and protein plaques (see Glossary of Terms on page 60 ) develop in the areas surrounding neurons.
• Tiny structures inside neurons that metabolize energy for cell functions become more susceptible to damage.
• Inflammation (swelling) of the brain increases, which cause damage to nerve cells.
• Oxidative stress increases. This is caused by the release of special molecules, called free radicals, from normal cellular processes. This can lead to nerve cell damage and death.

In healthy older people, the impact of these changes may be modest, resulting in various degrees of age-related memory decline. In people who have Alzheimer’s, however, some of these changes are much more extreme, with devastating consequences. Determining how the brain changes under normal aging conditions and what relevance these have to Alzheimer’s is an important area of research.

Food and Diet

There is a growing pool of evidence that suggests that what you eat is very important to your brain. A range of recent studies have reported a link between dietary habits and specific nutritional factors to the risk for Alzheimer’s disease and/or cognitive decline.

In particular, the benefits to the brain of a low-fat diet rich in antioxidants such as vitamins E and C throughout life are becoming clearer.

Here’s what some of the latest research studies have found :

• A diet rich in foods containing vitamin E may help protect against Alzheimer’s in some people, according to a study conducted at Rush-Presbyterian-St. Luke’s Medical Center in Chicago and reported in the prestigious Journal of the American Medical Association (JAMA).

Such foods include vegetable oils, nuts, green leafy vegetables, and whole grains. Furthermore, the protective effect was NOT seen when study participants took vitamin E supplements, as opposed to getting more of the vitamin from foods. The most significant protective effect was found among those who had the highest dietary intake of vitamin E (which averaged 11.5 International Units per day); their risk of developing Alzheimer’s was 67 percent lower than people who consumed the least amount of vitamin E from food sources.

In addition, the researchers found that vitamin E is associated with protection against more general cognitive decline. Ongoing clinical trials are investigating whether vitamin E might be useful as a treatment for Alzheimer’s, and if it can be used to help prevent the disease.

• A study reported at the 2002 International Conference on Alzheimer’s Disease found that a low-fat, antioxidant-rich diet was associated with decreased risk of Alzheimer’s disease, an association that held up even in people who carry the APOE-4 gene, the only known genetic risk factor for late-onset Alzheimer’s.
• Researchers at Case Western Reserve University School of Medicine found that people who ate primarily lean meats (fish and poultry) and fruits and vegetables during midlife had a lower risk of developing Alzheimer’s than people who ate a diet higher in fat and sugar and consisting of larger amounts of red and processed meats.
• A Netherlands study, published in the Journal of the American Medical Association (JAMA), reported a link between high dietary intake of vitamins E and C and protection against Alzheimer’s disease in certain people. Both vitamins have antioxidant properties that experts believe may help reduce damage to nerve cells caused by oxidative stress, which occurs throughout the body as a natural consequence of aging and may contribute to Alzheimer’s disease in ways that are not fully understood.
• Two studies point to the importance of B vitamins and levels of homocysteine, a compound found in the blood that has been linked to increased risk of certain cardiovascular conditions, including stroke and damage to the arteries.
• The first study, published in the American Journal of Clinical Nutrition, found that people with increased levels of homocysteine and deficiencies in vitamin B-12 and folic acid, another B vitamin, achieved lower scores on cognitive tests.
• A second study, reported at a major Alzheimer’s conference, found elevated homocysteine levels and low levels of vitamin B-12 in African-Americans with Alzheimer’s disease.

Taken as a whole, these and many other studies support the idea that eating the right food throughout your life is just as important to long-term cognitive health as it is to heart health.
A number of long-term, prospective clinical trials are now underway to test the effectiveness of vitamin E and other antioxidants in preventing or postponing cognitive decline and Alzheimer’s disease. Several are funded by the National Institute on Aging.

Consumption of Metals

Aluminum

One of the most alarming and controversial hypotheses about the potential risk factors for Alzheimer’s concerns aluminum, which became a suspect when researchers found traces of this metal in the brains of Alzheimer’s patients.

This is indeed a grave concern because many people use aluminum pots and pans for cooking, and aluminum canteens for drinking in the world.

Many studies since then have either not been able to confirm this finding or have had questionable results. Aluminum does turn up in higher amounts than normal in some autopsy studies of Alzheimer’s patients, but this certainly doesn’t occur in all. In addition, the aluminum found in some studies may have come from substances used in the laboratory to study the brain tissue after death.

Moreover, various other studies have found that groups of people exposed to high levels of aluminum do not have an increased risk of developing Alzheimer’s.

On the whole, scientists can say that it is still very debatable whether exposure to aluminum plays any role in the development of Alzheimer’s disease.

Zinc

Zinc has been implicated in Alzheimer’s disease in various studies.

Some research reports suggest that too little zinc may be a problem, while other studies suggest that too much zinc is an issue.

Too little zinc was suggested by autopsies that found low levels of zinc in the brains of Alzheimer’s disease patients, especially in the hippocampus, the part of the brain involved in learning and memory.

However, other studies suggest that too much zinc might be the problem. In laboratory experiments, zinc caused the formation of soluble beta amyloid from cerebrospinal fluid to form clumps similar to the plaques seen in the brains of Alzheimer’s sufferers.

Current experiments with zinc are continuing, with new laboratory tests that closely mimic conditions in the brain.

Weight, Blood Pressure, Heart Disease and Cholesterol

There is growing evidence that many of the well-established risk factors for cardiovascular disease, including high cholesterol and high blood pressure, may also be risk factors for Alzheimer’s disease.

Brain infracts, heart disease and mid-life hypertension increase the risk of Alzheimer’s disease and Vascular dementia.

A large study by researchers in Finland supports this thinking. Among the study population of 1,449 people, elevated cholesterol and high blood pressure seemed to be even more strongly linked to the eventual development of Alzheimer’s than did carrying APOE-4 gene, the only known inherited risk-factor for the most common form of the disease.

Those people who carried the APOE-4 gene were twice as likely to develop Alzheimer’s than those with no genetic risk. However, if those APOE-4 carriers also had high blood pressure, then they were up to five times as likely to develop the disease.

When high cholesterol was also present, the risk jumped to eight times greater than those without APOE-4.

This and a number of other studies around the world are strongly indicating that what’s good for the heart - keeping weight, cholesterol and blood pressure in check - may also be good for the brain.

Cholesterol is essential for healthy brain function - it is a component of cell membranes (structures that enclose nerve cells), and it is required for the repair and establishment of new connections between nerve cells. However, studies have shown that high cholesterol in mid-life and late-life can significantly increase the risk of Alzheimer’s Disease. Subsequent studies have indicated that cholesterol lowering drugs may lower the risk of developing Alzheimer’s disease.

Smoking

Smoking, another well-established risk factor for cardiovascular disease, has also been identified as a risk factor for Alzheimer’s .

Diabetes

Recent studies have found that having diabetes also seems to increase the risk of developing Alzheimer’s by up to 65%. This risk can be reduced by careful management of diabetes with medications that maintain blood glucose levels within a healthy range.

High Homocysteine Levels

Homocysteine is a by-product of many metabolic reactions occurring in our body. Some studies have found that high homocysteine levels are associated with an increased risk of Alzheimer’s Disease and other dementias. Adequate intake of vitamin B and folate can help reduce homocysteine levels.

Head Trauma History

Some studies have found that Alzheimer’s occurs more often in people who have suffered traumatic brain injury earlier in life. For example, people who have received a number of concussions from motorcycle or horse riding accidents seem to be more likely to develop Alzheimer’s later in life.

A study of World War II veterans also indicated that moderate to severe head injury increased risk of developing Alzheimer’s disease and other dementias. Other studies have found that this risk is further increased if the head injury resulted in loss of consciousness.

Some sports, such as boxing, also have definite links with Alzheimer’s, especially where a person has been forcefully punched over a number of years and knocked out on one or more occasions.

Further research is required to further study this potential link.

Education Level

Other research suggests that people with more years of formal education are less likely to develop Alzheimer’s.

Some experts theorize that longer education may produce a denser network of synapses in the brain. Synapses are the nerve-fiber connections in the brain that enable neurons to communicate with one another.

A dense synapse network may create a kind of "neural reserve" that enables people to compensate longer for the early brain changes associated with Alzheimer’s.

However, there could be other answers to this. Further research is required.

Early Life Experiences

Unsurprisingly, the environment in which a person lives - especially early in life - has been implicated as a risk factor for many chronic adult diseases, including Alzheimer’s.

However, a recent study has linked a surprising selection of environmental, socio-economic, and early life experience factors to Alzheimer’s. For example :

• An increased number of siblings was associated with increased risk of Alzheimer’s.
• A rural residence in childhood, combined with fewer than six years of school, was associated with an increased risk for Alzheimer’s.
• Growing up in the country, rather than in the suburbs, was associated with an increased risk for Alzheimer’s.

These findings were not explained by patients’ educational level or whether they carried the APOE gene that is associated with Alzheimer’s.

Such results appear to support a possible link between socio-economic or environmental variables and altered brain growth and development, which in turn may affect the risk of developing Alzheimer’s disease later in life.

A number of researchers have conducted these types of epidemiological studies to learn about the various factors that can have an impact on the development of Alzheimer’s.

Though such findings can be suggestive and interesting, they can also be conflicting or incomplete and highly controversial, because different teams of investigators may use different study methods and because of the complexity of the issues and the mind-boggling number of variables involved.

For example, low educational attainment may actually be a result of other socio-economic or environmental influences in childhood.

Further research is definitely required.

Hormone Replacement Therapy (HRT)

Several studies indicate that Hormone Replacement Therapy (HRT) may help delay the onset of dementia in women.

However, these findings have recently been contradicted by the large Women’s Health Initiative study which found that HRT, when given later in life, may have a negative effect on cognition.

The findings of these studies are further complicated by suggestions that the effect of HRT may be dependant on recipient’s genetic make-up or other factors. For example, it is possible that HRT has a negative effect on cognition of women who carry ApoE4 allele.

Nutrients and plant devivatives may help prevent and treat the
progression of impaired brain function. Antioxidants and B
Vitamins help reduce inflammatory damage to the central vervous
system. Essential fatty acids such as fish oil, flax seed oil,
and evening primrose oil help nourish the brain. Lecithin
contains choline which stimulates the production of
acetylcholine and may help with memory function. Suggested
doasage is 100 mg. three times a day with meals. Lecithin comes
in granules or softgels. Alpha Lipoic Acid (ALA) has shown an
improvement in long-term memory impairment, and has been
researched since the 1950’s as a treatment for Parkinson’s
Disease and Alzheimer’s. Alpha Lipoic Acid can reduce damage to
neurons caused by toxic substances that are products of
inflammatory processes. ALA is also involved with numerous
metabolic functions, including glucose metabolism, liver
function, energy production in muscles and nervous systme
function, which ultimately affects the brain.