Feature

posted 3 Aug 2005 in Volume 10 Issue 5

Understanding Alzheimer’s disease and related dementias

Geriatric care manager Leanne Smelt provides non-medical professionals with a helpful insight into the medical nature of the dementias and Alzheimer’s afflicting 750,000 older people in the UK.

What is dementia?

Dementia is the loss of mental function in two or more areas, such as memory, language, visual or spatial abilities, or judgment severe enough to interfere with daily life.

Dementia itself is not a disease, but a broader set of symptoms that accompanies certain diseases and physical conditions.

The well-know diseases that cause dementia include Alzheimer’s disease, multi-infarct dementia, Parkinson’s disease, Huntington’s disease, Creutzfeldt-Jakob disease, Pick’s disease and Lewy body dementia.

There are other physical conditions that may cause or mimic dementia, such as brain tumours, depression, head injuries, nutritional deficiencies, infections (AIDS, meningitis, syphilis), drug reactions and thyroid problems.

If someone is experiencing dementia-like symptoms they should undergo diagnostic testing as soon as possible.

Early and accurate diagnosis helps to identify reversible conditions and allows patients to benefit from existing treatments and allows them and their families more time to plan for the future.

Statistics

Dementia currently affects over 750,000 people in the UK. Over 18,000 people with dementia are aged less than 65 years of age. Dementia affects one person in 20 over 65 years of age and one person in five over 80 years of age.

The well-established prevalence rates (frequency with which dementia occurs in the population) for dementia in the UK are shown below.

Ages 40-65 = prevalence of 1 in 1,000

Ages 65-70 = prevalence of 1 in 50

Ages 70-80 = prevalence of 1 in 20

Ages 80+ = prevalence of 1 in 5

It is estimated that by 2010 there will be about 870,000 people with dementia in the UK. This is expected to rise to over 1.8 million people with dementia by 2050.

Alzheimer’s disease is the most common form of dementia. There is some disagreement over precise numbers; the proportions of those with different forms of dementia can be broken down as shown below.

Alzheimer’s disease 55%

Vascular dementia 20%

Dementia with lewy bodies 15%

Fronto-temporal dementia including Pick’s disease 5%

Other dementias 5%

With our population ageing the number of people with dementia is expected to increase steadily over the next 25 years. There are over five million people with dementia in Europe. There are nearly 18 million people with dementia in the world. By 2025, there will be about 34 million people with dementia in the world. By 2025, 71 per cent of people with dementia will live in developing countries¹.

Normal memory loss or Alzheimer’s disease?

Health professionals use the term ‘age-associated memory impairment’ (AAMI) to describe the minor memory difficulties that come with age. AAMI is not progressive or disabling, whereas Alzheimer’s disease is both.

Some ways to tell if memory loss is more serious than AAMI are:

Alzheimer’s disease is progressive, whereas AAMI may remain unchanged for years;
People with AAMI can usually compensate memory loss with reminders and notes;
Memory loss associated with Alzheimer’s disease will begin to interfere with activities of daily living;
Alzheimer’s disease will affect more than memory, impairing the ability to work with figures, use words, solve problems and use reasoning and judgement. It often affects personality and mood.

How is the diagnosis made?

There is no single test to detect Alzheimer’s disease. The ability to detect the abnormal structures in the brain of a living person does not currently exist. A diagnosis is based on a thorough evaluation of symptoms and an assessment of an individual’s health. If an individual is concerned about themself or someone close to them, they should contact their GP to discuss their concerns.

A specialist consultant will use a variety of tests to assess memory and thinking skills. They will also consult the family concerning changes in the individual’s memory and behaviour.

A physical examination, review of the individual’s medical history, and various laboratory tests that may require blood or urine samples or brain-imaging scans may be conducted. The Mini Mental State Examination (MMSE) is the most commonly used test to assess complaints of memory or when diagnosis of dementia is being investigated.

All of this information can help the consultant identify the most probable cause of symptoms and rule out treatable conditions that may cause memory impairment and other dementia symptoms. Such conditions may include depression, adverse drug reactions and nutritional deficiencies.

With continued research, diagnostic tools will improve. This will hopefully lead to earlier diagnoses and therefore earlier treatment.

Causes of Dementia

Alzheimer’s Disease

Alzheimer’s Disease (AD) is a disorder that destroys brain cells. This is the leading cause of dementia, a condition that involves gradual memory loss, loss of ability to perform routine tasks, difficulty in learning, disorientation, loss of language skills, impairment of judgement and personality changes. As the disease progresses, those with the disease are unable to care for themselves. With the loss of brain cells, eventually other systems in the body will fail. The rate of progress varies from person to person.

Dr. Alois Alzheimer, a German physician, first described the disease in 1906. He observed an autopsy of a woman with dementia. There are two kinds of abnormal structures in the brain that are recognised as hallmarks to Alzheimer’s disease: amyloid plaques and neurofibrillary tangles.

The risk of developing Alzheimer’s disease increases with age. A family history is another known risk. Having a parent or a sibling with the disease increases the risk of developing Alzheimer’s disease.

A definitive diagnosis of Alzheimer’s disease can only be made through examination of brain tissue at autopsy.

Multi-infarct dementia

Multi-infarct dementia (MID) or vascular dementia is a deterioration of mental capacity due to multiple strokes (infarcts) in the brain. Often described as ministrokes, where small blood vessels in the brain become blocked by blood clots, causing destruction of brain tissue. Onset of MID may appear sudden, but it may take several strokes for symptoms to appear.

The strokes may damage areas of the brain that are responsible for a particular function, as well as general dementia symptoms. MID is sometimes misdiagnosed as Alzheimer’s disease.

MID is not reversible or curable, but early detection of high-blood pressure or other vascular risk factors can lead to treatment that can modify MID’s progression.

Parkinson’s disease

Parksinson’s disease (PD) is a progressive disorder of the central nervous system. In PD, certain brain cells deteriorate for reasons not yet known. These cells produce a substance called dopamine, which helps control muscle activity.

PD is often characterised by stiffness in joints and limbs, tremors, speech difficulties and problems initiating physical movement. Later in the disease, some patients develop dementia and some patients often have dual diagnoses.

Huntington’s disease

Huntington disease (HD) is an inherited, degenerative brain disease that causes both physical and mental decline and begins in mid-life.

Early symptoms vary from person to person but include difficulty concentrating, involuntary movement of limbs or facial muscles. Other symptoms are personality changes, memory impairment, slurred speech and impaired judgement.

Children born to a person with HD have a 50 per cent chance of inheriting the gene that causes HD (Alzheimer’s Association). A genetic test is available to confirm diagnosis of HD and to identify carriers of HD.

No treatment is available to stop the progression of HD, but the movement difficulties and psychiatric symptoms can be treated with medication.

Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder that causes rapid, progressive dementia and other neuromuscular problems.

Creutzfeldt-Jakob disease was first reported by two German doctors (Creutzfeldt and Jakob) in 1920. A transmissible agent causes CJD.

Early symptoms of CJD include changes in behaviour, failing memory and lack of concentration. As the disease progresses and very rapidly, deterioration becomes more pronounced, muscle jerks appear, severe difficulty with sight, muscular energy and coordination.

Like Alzheimer’s disease, a definitive diagnosis of CJD can only be made through examination of brain tissue at autopsy.

Pick’s disease

Pick’s disease (PD) is also a rare brain disorder, characterised by the shrinkage of the tissues of the frontal and temporal lobes of the brain and by the presence of abnormal bodies (Pick’s bodies) in the nerve cells of the affected areas of the brain.

Pick’s disease usually begins between the ages of 40 and 60 (Alzheimer’s Association). Symptoms are similar to Alzheimer’s disease. The initial diagnosis is based on family history (Pick’s disease may be inherited).

A definitive diagnosis is usually obtained at autopsy.

Lewy body dementia

Lewy body dementia (LBD) is an irreversible form of dementia associated with abnormal protein deposits in the brain called Lewy bodies.

Symptoms of LBD are similar to Alzheimer symptoms. Hallucinations and paranoia also may become apparent in the earlier stages of the disease and often last throughout the disease process.

Initially symptoms of LBD may be mild, but eventually severe cognitive impairment develops. There is no treatment available for Lewy body dementia.

References:

Source: Policy Positions: Alzheimer’s Society, July 2004
Source: Care of Alzheimer’s Patients: A Manual for Nursing Home Staff, by Lisa P. Gwyther, ACSW, member, Committee on Patient and Family Services, Alzheimer’s Association.

Useful websites

· Alzheimer’s Society: www.alzheimers.org.uk

· Alzheimer’s Association: www.alz.org

· British Medical Society: www.bmis.org

· Help the Aged: www.helptheaged.org.uk

· Huntington’s Disease Association: www.had.org.uk

· Parkinson’s Disease Society: www.parkinsons.org.uk

· Stroke Association: www.stroke.org.uk

Leanne Thompson-Smelt, MSc. is a geriatric care manager who has relocated from the US to the UK. She has over 16 years’ experience in the geriatric field and expertise in Alzheimer’s disease and related dementias. She has provided care management and expert-witness advice for solicitors. She can be reached on 01405 760225 or at leanne@cleverpeople.co.uk