Alzheimer's disease - causes, symptoms, prevention

Alzheimer’s disease is the most common form of dementia, where a person’s memory, thinking, understanding and judgement declines.

The frequency of Alzheimer's disease is increasing as the New Zealand population ages. It has been estimated that the number of New Zealanders living with Alzheimer's disease will reach 70,000 by 2031 (from 28,000 in 2006).

There is no cure for Alzheimer's disease, nor any proven ways to prevent its onset. Treatment focuses on support and managing symptoms to maximize a person's ability to carry out daily activities and tasks so that they maintain their independence for as long as possible. The condition is ultimately fatal.

Causes

In Alzheimer’s disease, brain cells start to deteriorate, lose connections with each other, and eventually die.

These changes are associated with the build-up of abnormal proteins that form “plaques” and “tangles” around the brain cells.

It is unknown whether plaques and tangles themselves cause Alzheimer’s disease or whether they are a part of the disease process.

Researchers believe that a combination of lifestyle, environmental, and genetic risk factors trigger the abnormal biological process in the brain that, over decades, results in Alzheimer-type dementia. Identified risk factors for developing the condition include:

Increasing age
Family history – a person who has a parent or sibling with Alzheimer’s is more likely to develop the disease
Down syndrome
History of a head injury
Risk factors for blood vessel disease such as smoking
Lack of regular exercise
Poor sleep habits
Obesity
High blood pressure
High blood cholesterol
Poorly controlled type 2 diabetes
Long term exposure to solvents (e.g. paints and glues).

Signs and symptoms

The changes that occur with Alzheimer's disease affect the areas of the brain that control thought, memory and language resulting in the gradual onset of signs and symptoms related to a person’s behaviour and mental function. Often, physical functions such as bowel and bladder control are also affected.

The symptoms of Alzheimer's disease typically develop quite slowly. The time between the onset of the disease and death can range from five to 20 years. The types of behaviour change, and the time over which symptoms develop, are different for each person.

Symptoms commonly experienced during the early stages of Alzheimer's disease include:

Mild forgetfulness – especially short-term memory loss
Mood changes, including irritability and anxiety
Difficulty processing new information and learning new things
Loss of spontaneity and initiative
Confusion about time and place
Communication difficulties
Decline in ability to perform routine tasks.

As Alzheimer’s disease progresses the following symptoms may develop:

Increasing short-term memory loss and confusion
Difficulty recognising family and friends
Shorter attention span and feelings of restlessness
Difficulty with reading, writing and numbers
Neglectful of hygiene
Loss of appetite
Personality changes (eg: aggression, significant mood swings)
Requires increasing assistance with daily tasks.

Towards the later stages of the disease the following symptoms may be experienced:

Inability to understand or use speech
Incontinence
Inability to recognise self or family
Severe disorientation
Increasing immobility and sleep time.

The changes brought about by Alzheimer's disease can be increasingly difficult for family members and friends as the person’s condition deteriorates, they lose their independence, and become unable to recognise loved ones.

Although a person loses many abilities as the disease progresses, it is often helpful to focus on the abilities they still have, such as the senses of touch and hearing and the ability to respond to emotion.

Diagnosis

A range of steps will be involved in reaching a diagnosis of Alzheimer’s disease:

Assessing a person’s medical and psychiatric history
A neurological and physical examination
Blood and urine tests
Brain scans
Mental status assessment to determine the level of mental deterioration
Caregiver interview to determine the level of dependency.

Scans (such as CT, MRI and PET) to check brain structure and function may be recommended.

Treatment

As there is no known cure for Alzheimer’s disease, treatment focuses on managing symptoms and supporting the person and their family. This may include:

Treating medical conditions that may contribute to confusion or physical decline, eg: lung disease or anaemia
Participating in stimulating activities to encourage the person to continue their normal activities as much as possible
Providing memory aids and memory triggers such as calendars and written reminders
Encouraging social interaction to help prevent feelings of loneliness and depression
Contacting support groups that may be able to offer family/caregivers assistance
Encouraging a regular daily routine to reduce confusion
Not smoking.

Medications

Medications such as sleeping tablets, tranquillisers and antidepressants may help to control symptoms such as sleeplessness, agitation and aggression, and depression. However, sleeping tablets and tranquillisers can cause increased confusion, so their use should be limited.

A group of medications called cholinesterase inhibitors improve mental function (thinking and memory) and daily living abilities in some people. Cholinesterase inhibitor medications that are available in New Zealand include donepezil, rivastigmine, and galantamine.

Another drug - memantine – may also help ease memory loss symptoms.

Prevention

There are no proven ways to prevent the development of Alzheimer's disease. However, some evidence suggests that a healthy lifestyle can reduce the risk of Alzheimer's disease.

Regular physical activity and exercise may have a general protective effect on brain health and may slow progression of Alzheimer's disease.

Although there are no specific dietary specifications for Alzheimer's, a "Mediterranean-style" diet (ie: plant foods such as vegetables, fruits, beans, whole grains, nuts, olives and olive oil, along with some cheeses, yoghurt, fish, poultry and eggs) may reduce the risk of Alzheimer's disease. A Mediterranean-style diet has the added benefit of lowering cardiovascular disease and type 2 diabetes risk. For more diet information, refer to our Healthy heart diet.

Further support

Alzheimers New Zealand (National Office)
Freephone: 0800 004 001
Email: admin@alzheimers.org.nz
Website: www.alzheimers.org.nz

References

Alzheimer Society of Canada (2019). Stages of Alzheimer's Disease (Web Page). Toronto: Alzheimer Society Canada. www.alzheimer.ca/en/About-dementia/Alzheimer-s-disease/Stages-of-Alzheimer-s-disease [Accessed: 06/05/20]
Alzheimer Society of Canada (2020). Alzheimer's disease (Web Page). Toronto: Alzheimer Society Canada. http://www.alzheimer.ca/en/About-dementia/Alzheimer-s-disease [Accessed: 06/05/20]
Mayo Clinic (2018). Alzheimer’s disease (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/alzheimers-disease/home/ovc-20167098 [Accessed: 06/05/20]
Lakhan, S.E. (2029). Alzheimer disease (Web Page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. http://emedicine.medscape.com/article/1134817-overview [Accessed: 06/05/20]
Tobias, M, Yeh, L.C., Johnson, E. (2008). Burden of Alzheimer's disease: population-based estimates and projections for New Zealand, 2006-2031. Aust NZ J Psychiatry; 42(9):828-36.

Last Reviewed – June 2020