Symptoms and Risk factors for Alzheimers

Canadian baby boomers seem to know precious little about Alzheimer's disease -- even a startling number of those who have a family member of friend with the disease, a new survey reveals. The online survey of more than 1,000 respondents aged 45-65 was conducted by the Alzheimer Society. It finds that many couldn't even name "memory loss" as being a warning sign of the incurable brain disease. In fact, almost one in four people could not name a single symptom of Alzheimer's.

Only 51 per cent knew that having difficulty recognizing people, names, words, dates, places, or doing everyday tasks is a warning sign of the disease. And only 48 per cent knew that signs of short-term memory loss, such as losing or misplacing things, is also a sign of the degenerative disease. Far fewer respondents could identify other common symptoms such as disorientation of time or place, repetitive behaviour and wandering.

Once the respondents were presented with a list of 10 symptoms, more than 90 per cent realized they had heard that frequent memory loss was a key symptom. As well, 85 per cent said they had heard that disorientation, such as getting lost in a familiar place, was a symptom. Strangely, even those who were personally touched by the disease fared only slightly better compared to those with no experience of the illness. For example, 17 per cent of people who said they had a family member or friend with Alzheimer's disease could not name any of the signs of the disease without being prompted.

The survey also found many were unaware of Alzheimer's risk factors.

When respondents were presented with a list of 13 risk factors and asked to identify which factors they had previously known about, close to 80 per cent said they knew that increasing age raised the risk of being diagnosed with Alzheimer's. And 53 per cent said they knew that a lack of mental or social stimulation also raises the risk. But a full 10 per cent said they were not aware that any of the factors increased one's risk for the disease.
The Alzheimer society says the results are startling, given that some of the respondents might one day be affected by Alzheimer's. That's because the risk of the disease doubles every five years after age 65.
The survey included a geographically, nationally representative sample of 1,006 online respondents and was completed in July 2010.

What are the risk factors associated with Alzheimer's disease?


Age

Age is the most important risk factor. As we age, our body's ability to repair itself becomes less efficient. The extent by which the self-repair of our brains diminishes varies from person to person and these differences contribute to an individual's susceptibility to Alzheimer's disease as they age. As well, many of the other known risk factors for the disease tend to increase with age (such as elevated cholesterol and being overweight). However, risk factors do not cause Alzheimer's disease on their own. The brain has to reach a certain critical age for the disease to occur. The older you become the higher the risk – 1 in 20 Canadians over age 65 and 1 in 4 of those over age 85 are affected by Alzheimer's disease.

Family history and Genetics
A very small percentage of people with Alzheimer's disease (5-7%) has Familial Alzheimer's disease or FAD (formerly known as "early onset Alzheimer's disease"). At some point in their family history certain genes mutated and developed the abnormal characteristics that cause FAD. These inherited genes have a powerful influence: if one parent has FAD, each child has a 50 % chance of inheriting the disease, and with two parents with FAD, 75% of their children will go on to develop Alzheimer's disease in adulthood. These inherited genes differentiate FAD from the more common sporadic form of Alzheimer's disease, but the disease itself is identical.

The sporadic form of Alzheimer's disease (which used to be called "late onset Alzheimer's disease"), was formerly assumed to have no family linkages. However, it's now known that a person with a direct relative (parent or sibling) with Alzheimer's disease has a three times greater chance of developing the disease than someone who does not.* The risk increases further if both parents have the disease. So aside from the FAD-related genes there are Alzheimer's disease-related genetic factors shared by family members.New research is revealing more and more genetic risk factors for the sporadic form of Alzheimer's disease. That means that these genes are found to a greater extent among those with the disease, though they are also found in people without Alzheimer's disease. People with these genetic risk factors are not in the same high-risk category as people who have the mutated genes responsible for FAD. In fact, the risk associated with any one of these newly discovered genetic risk factors is lower than the risk associated with having a parent with the sporadic form of the disease (with the exception of the apoE4 gene discussed below).Please refer to the Alzheimer Society's Informatin Sheet on Alzheimer's Disease and Heredity for more information.

*Here is a useful way of looking at the relative risk: of 100 people with no defined genetic risk factor, 5 will get Alzheimer's disease at age 65 (and 95 will not). Of 100 people, each with a parent with Alzheimer's disease, 15 will get Alzheimer's disease at age 65 (and 85 will not).

ApoE4 Gene

This gene is the most important genetic risk factor for the sporadic form of Alzheimer's disease. ApoE genes regulate the production of a protein that helps carry cholesterol and other fats in the blood to the cells of the body. Of the three variants of the apoE gene (apoE2, apoE3 and apoE4), the apoE4 variant is associated with an increased risk of Alzheimer's disease.In our cells (except ova and sperm) all genes are paired, one being contributed by the father and one by the mother. If a person's pair of apoE genes includes one apoE4 gene, their risk of developing Alzheimer's disease is increased. However, approximately half of all people with two apoE4 genes will develop Alzheimer's disease at age 65. People with no apoE4 genes can still get Alzheimer's disease and people with two apoE4 genes will not necessarily get the disease.
Female Gender
Twice as many women get Alzheimer's disease than men. Many believe that it is in a large part a result of the changes to women's hormones at menopause, in particular the decline of the important hormone estrogen. In the past estrogen was often prescribed to relieve symptoms of menopause and to reduce the risk of developing Alzheimer's disease. However, a fairly recent large-scale clinical study recommended discontinuation of Hormone Replacement Therapy (HRT) because of potentially dangerous side effects. A number of clinical researchers regard HRT as worthy of further study especially in the context of Alzheimer's disease. Any decision regarding the use of HRT should be made in consultation with a physician.

However, hormonal changes are not the only factor contributing to the increased incidence of Alzheimer's disease in women. On average, women live longer than men and age is a risk factor. Women are also more prone to diabetes, which is also a risk factor (see below), and recently, a gene was identified that occurs only in women, and appears to somewhat increase the risk for Alzheimer's disease.

Cardiovascular Disease
All the risk factors for cardiovascular disease (such as high blood pressure and high cholesterol levels) are also risk factors for both Alzheimer's disease and Vascular Dementia. Strokes and mini-strokes (the latter detected largely through later testing), are also well-accepted risk factors for Alzheimer's disease and for Vascular Dementia.

Diabetes
It has been known for some time that type 2 ("Adult") diabetes is a risk factor for Alzheimer's disease. It has been generally assumed that the two are linked by cardiovascular disorders, which are associated with diabetes and are risk factors for Alzheimer's disease. It has also been known that the utilization of glucose in the brains of people with Alzheimer's disease is impaired, somewhat resembling the situation in the bodies of people with type 2 diabetes.
An even more recent finding suggests that the Alzheimer's brain has a diabetes-like condition that some are calling type 3 diabetes. Researchers have found that in people with Alzheimer's disease the production of insulin in the brain is reduced and the nerve cells are less sensitive to it. (Production of insulin in the brain is independent of insulin production in the pancreas, the major insulin-producing organ). Anti-diabetic drugs that target the brain are now being tested in people with Alzheimer's disease.
Recently evidence was also presented that children with type 1 ("Juvenile") diabetes are at risk for developing Alzheimer's disease in later life.

Down Syndrome
Almost all individuals with Down syndrome who live into their forties and beyond will develop the abnormal changes in the brain (the plaques and tangles) that characterize Alzheimer's disease. It is important to note, however that not all people with Down syndrome who develop these brain changes will go on to develop dementia. It seems likely that these people may not yet have developed other age-induced changes that occur in most people with Alzheimer's disease. Please refer to the Alzheimer Society's Information Sheet on Alzheimer's Disease and Down Syndrome for more information.

Mild Cognitive Impairment (MCI)
In MCI, there is a level of cognitive and/or memory impairment beyond that expected for normal aging but not sufficiently advanced to be called "dementia" or "Alzheimer's disease." It is estimated that up to 85% of people with MCI, who are often in their early forties or fifties, will develop Alzheimer's disease within ten years, making MCI an important risk factor for the disease. Researchers now know that the abnormal changes in the brain characteristic of Alzheimer's disease can begin to appear in people diagnosed with MCI twenty or more years before there are signs of dementia. Brain imaging may make it possible to detect the most at-risk individuals with MCI, and research to this end is ongoing.

Head injury
Brain injuries at any age, especially repeated concussions, are accepted by most clinicians as risk factors for the later development of Alzheimer's disease.

Low Levels of Formal Education

Several studies have shown that people who have less than six years of formal education appear to have a higher risk of developing Alzheimer's disease. It has been assumed that the brain stimulation associated with learning provides a protective effect for the brain; therefore more education provides greater protection. However, new studies challenge this conclusion, and it may be that factors often associated with low educational background, such as unhealthy lifestyle, account for the risk rather than low educational level itself.

Other Risk Factors
In addition to the risk factors described above, all of the following have been documented as risk factors for Alzheimer's disease: inflammatory conditions (possibly reflecting immune system malfunction), a history of episodes of clinical depression, stress, and inadequate exercising of the brain. Risk factors that are less firmly established include smoking, excessive alcohol consumption and drug abuse.

Aluminum
Most researchers no longer regard aluminium as a risk factor for Alzheimer's disease. However, some researchers are still examining whether some people are at risk because their bodies have difficulties in handling foods containing the metals copper, iron, and aluminium.