Dementia/Memory Loss

Researchers have highlighted some important factors that affect our risk of developing different types of dementia. Most now believe that our risk of developing dementia depends upon a combination of genetic and environmental factors. We are all at some risk of developing dementia, but some of us are more at risk than others. However, a person who has some of the risk factors for dementia will not necessarily go on to develop the condition.

Age

Age is the most significant known risk factor for dementia. It is possible to develop dementia early in life, but the chances of developing it increase significantly as we get older. One in 50 people between the ages of 65 and 70 has some form of dementia, compared to one in five people over the age of 80. This increased risk may be due to factors associated with ageing, such as:

• higher blood pressure
• an increased incidence of some diseases (for example, heart disease and stroke)
• changes to nerve cells, DNA and cell structure
• the weakening of natural repair systems.

Gender

Gender affects different types of dementia in different ways. Women are slightly more likely to develop Alzheimer’s disease than men, even if we discount the fact that women are more likely to live longer. One factor that has been suggested in the development of Alzheimer’s disease is a lack of the hormone oestrogen in women after the menopause. However, controlled studies have suggested that hormone replacement therapy (HRT) has no beneficial effect on the development of Alzheimer’s disease, and may even increase a person’s risk of developing the condition. It is not recommended that women take HRT as a way to reduce their risk of developing dementia.

Vascular dementia, on the other hand, seems to be more common in men than women. This may be because common risk factors for vascular dementia, such as heart problems and high blood pressure, are more common in men than women.

Genetics

Scientists have been aware for some time that the genes we inherit from our parents may partly determine whether we will develop specific diseases. The role of genetics in the development of dementia is still not fully understood, but researchers have made some important advances in recent years.

There are some families in which there seems to be a very clear inheritance of dementia from one generation to the next. This is usually in families where the disease appears relatively early in life. Dementia-causing diseases that may be hereditary in some cases include Huntington’s disease, Familial Alzheimer’s disease (a very rare form of Alzheimer’s) and Niemann-Pick Type C disease.

Certain genes can affect a person’s risk of developing Alzheimer’s disease, and scientists are learning more about these. For example, a gene called apolipoprotein E (ApoE) has been shown to play a part in the development of Alzheimer’s disease and vascular dementia. However, having a parent or other relative with later onset Alzheimer’s disease only makes your own chances of developing it a little higher than if there were no cases of dementia in the family at all.

Medical history

Specific medical conditions can increase a person’s chances of developing dementia. These include multiple sclerosis, Huntington’s disease, Down’s syndrome and HIV. Conditions that affect the heart, arteries or blood circulation can particularly affect a person’s chances of developing vascular dementia. These conditions include mid-life high blood pressure and high blood cholesterol levels, stroke, diabetes, and heart problems such as a heart attack or irregular heart rhythms. Mid-life obesity can also increase a person’s risk of developing dementia in later life.

People who suffer severe or repeated head injuries are at a three-to-four-fold increased risk of developing dementia. It is possible that deposits that form in the brain as a result of the injury may be linked to the onset of dementia. Professional boxers sometimes develop a form of dementia known as ‘dementia pugilistica’.

Diet − Diet can affect a person’s risk of developing many types of illness, including dementia. A healthy and balanced diet that enables a person to maintain a normal body weight is likely to reduce the likelihood of developing high blood pressure or heart disease, both of which put a person at greater risk of developing dementia.

Too much saturated fat can cause narrowing of the arteries, making heart attack or stroke more likely − and heart attacks, stroke and vascular disease increase a person’s risk of developing vascular dementia.

Smoking − Smoking has an extremely harmful effect on the heart, lungs and vascular system, including the blood vessels in the brain. This increases the risk of developing vascular dementia. Despite early studies which suggested that smoking might cause a reduced risk for Alzheimer’s disease, more recent epidemiological research has shown that smoking is a significant risk factor for Alzheimer’s disease, with smokers almost twice as likely to develop the disease as non-smokers.

Alcohol − People who drink excessive amounts of alcohol over a long period of time increase their risk of developing a form of dementia. However, some research has suggested that moderate amounts of red wine, which contains antioxidants, might help to protect the brain against dementia and keep the heart and vascular system healthy.

Aluminium and other metals − Trace levels of many metals are present in the brain. Aluminium is the metal that has been most often studied in this context, and that has received the most publicity. Aluminium is extremely common within the environment, and exists in many different chemical forms, so exposure is very difficult to measure. However, the majority of scientists do not believe that there is a causal link between aluminium and Alzheimer’s disease. Other metals, such as copper and zinc, may be important in the way that key proteins are processed in the brain.

While the source of aluminium toxicity in the body has not yet been proven, aluminium can enter the body through inhalation (by factory workers in certain industries) and by oral ingestion. It has been suggested that aluminium ions may leach into the body from aluminium cooking utensils, cans, and foil, as well as underarm deodorants, antacid pills, and other common products, many of which contain traces of aluminium. In addition, Aluminium is commonly used by water treatment plants to brighten drinking water. This causes the excess aluminium in the water to flow from the treatment plants to the communities downstream of these plants, causing the populations there to receive a double dose of aluminium.

Mercury Post mortem examination of brain tissue from Alzheimer’s victims has also indicated the presence of high levels of mercury. Reactions to high levels of mercury in the body can range from nervousness and depression to suicidal tendencies and severe neurological diseases such as multiple sclerosis, Lou Gehrig’s disease (a syndrome marked by muscular weakness and atrophy due to degeneration of motor neurons), and Alzheimer’s. Mercury metal fillings also create low levels of constant electrical activity that is conducted directly to the brain, creating aberrant behavior. While the electrical charge created by metals in the mouth does not itself directly suppress the immune system, it enables metals to leave the fillings faster and to be absorbed into the blood.

Environmental Influences: Toxins such as chemicals in food and tap water, carbon monoxide, solvents, aerosol sprays, and industrial chemicals can cause symptoms of brain dysfunction that may lead to an inaccurate diagnosis of Alzheimer’s or senile dementia.

Hormone Imbalances: The hormone melatonin plays a role in the synchronization of brain cells and, as a potent antioxidant, helps protect brain tissue from free-radical damage. Daily concentrations of melatonin appear to decline in those who have Alzheimer’s disease.

Stress and the stress hormones, particularly cortisol, play a major role in Alzheimer’s. Although some cortisol is needed for proper brain function, chronic exposure to toxic levels of cortisol can kills brain cells. Cortisol damages the nerve cells of the hippocampus and blocks their ability to absorb blood sugar (glucose), causing sluggish responses. Brain scans of Alzheimer’s patients show that the temporal (site of the hippocampus) and frontal lobes have a decreased capacity to absorb glucose.

Caution: Studies conducted at the University of Pittsburgh and Yale University found, after conducting autopsies of Alzheimer patients, that between seven and eleven per cent of all cases were due to Mad Cow Disease.

Impaired Blood Flow to the Brain: There may be a relationship between heart disease, reduced blood flow to the brain, and the onset of Alzheimer’s. According to Dr. Khalsa, a medical doctor from Tucson, Arizona, 77% of Alzheimer’s patients have cardiovascular disease. More than 85% of people 65 and older who suffer from coronary artery disease also exhibited brain tissue plaques similar to Alzheimer’s.

Nutritional Deficiencies: Reduced levels of certain vitamins, minerals, and amino acids have been tentatively linked with Alzheimer’s, including folic acid, niacin (vitamin B3), thiamin (vitamin B1), vitamins B6, B12, C, D, and E, magnesium, selenium, zinc, and tryptophan.

The brain functions through the transmission of chemical messenger molecules (neurotransmitters). These neurotransmitters can have far-reaching effects in distant areas of the body. Effective transmission of impulses is dependent upon proper pH (acid-alkaline balance) and the presence of a variety of nutrients (vitamins, minerals, amino acids), hormones, and neurotransmitters. If any nutrients are lacking or present in imbalanced proportions, brain function will be adversely affected and a person will display various symptoms commonly associated with dementia.

Dementia is caused by changes in the brain. Damage to the brain cells that gets worse over time causes the symptoms of dementia. This leads to a decline in a person’s mental and, sometimes, physical abilities.

In most cases, dementia is not inherited directly from family members. However, a small number of cases of Alzheimer’s disease and frontotemporal dementia run in families.

Dementia is often caused by diseases that damage the brain. These are known as neurodegenerative diseases. The gradual changes and damage to brain cells are caused by a build-up of proteins in the brain. These proteins are different in each type of dementia. Vascular dementia is caused when the brain’s blood supply is interrupted. If the blood supply is restricted or stopped, brain cells begin to die, resulting in brain damage.

The causes of the different types of dementia are listed below.

Causes of Alzheimer’s disease

Alzheimer’s disease is the most common form of dementia. In most cases of Alzheimer’s disease the brain shrinks, which damages the brain’s structure and how it works. The medical name for this is atrophy.

An area of the brain known as the cerebral cortex is particularly affected by atrophy. The cerebral cortex is the layer of grey matter covering the brain. Grey matter is responsible for processing thoughts.

Clumps of protein, known as ‘plaques’ and ‘tangles’, also start to form in the brain. The plaques and tangles start to destroy more brain cells, which makes the condition worse. They also affect the chemicals that carry messages from one brain cell to another. These chemicals are known as neurotransmitters.

Causes of vascular dementia

Vascular dementia is caused when the brain’s blood supply is interrupted.

Like all organs, the brain needs a constant supply of oxygen and nutrients provided by the blood to work properly. If the supply of blood is restricted or stopped, the brain cells will begin to die, resulting in brain damage.

If the blood vessels inside the brain narrow and harden the brain’s blood supply can gradually become interrupted. The blood vessels usually narrow and become hard when fatty deposits build up on the blood vessel walls, restricting the flow of blood. This is called atherosclerosis.

Atherosclerosis in the smaller blood vessels in the brain will also cause them to clog up gradually, depriving the brain of blood. This is known as small vessel disease.

If the brain’s blood supply is interrupted rapidly during a stroke, this can also damage the brain cells.

Not everyone who has had a stroke will go on to develop vascular dementia. However, if you have had a stroke, or you have been diagnosed with small vessel disease, you may have an increased risk of developing vascular dementia.

Causes of dementia with Lewy bodies

Lewy bodies are small, circular lumps of protein that develop inside the brain. It is not known what causes them. It is also unclear how they damage the brain and cause dementia.

One theory is that Lewy bodies interfere with the effects of two of the messenger chemicals in the brain – dopamine and acetylcholine. These messenger chemicals, which send information from one brain cell to another, are called neurotransmitters.

Dopamine and acetylcholine are thought to play an important role in regulating brain functions, such as memory, learning, mood and attention.

Dementia with Lewy bodies is closely related to Parkinson’s disease. This is a condition in which part of the brain becomes more and more damaged over a number of years, leading to physical symptoms, such as involuntary shaking (tremor), muscle stiffness and slowness of movement. A person with dementia with Lewy bodies may also develop these symptoms.

Causes of frontotemporal dementia

Frontotemporal dementia is caused by damage and then shrinking in two areas of the brain. The areas of the brain affected are called the temporal lobe and the frontal lobe. This type of dementia usually affects younger people who are under 65 years of age.

In an estimated 20% of cases, people who develop frontotemporal dementia have inherited a genetic mutation (an altered gene) from their parents.

Motor neurone disease is also sometimes associated with frontotemporal dementia. It is a rare condition that progressively damages the nervous system, causing the muscles to waste away.

Less common causes of dementia

Dementia or dementia-like symptoms can have a number of less common causes. These include:

infections of the brain, such as brain inflammation (encephalitis)

Huntington’s disease – a rare genetic condition that causes progressive brain damage

Creutzfeldt-Jakob disease (CJD) – a rare and fatal condition that causes damage to the brain and nervous system

a lack of vitamin B in the diet

having a brain tumour

rarer degenerative conditions, such as progressive supranuclear palsy and corticobasal degeneration

long-term HIV

long-term alcohol misuse