Alzheimer’s disease is the most common form of dementia and accounts for approximately 60% of all dementia cases. It is estimated that 28,000 New Zealanders are living with Alzheimer's disease and that number will reach 70,000 by 2031.
There is no cure for Alzheimer's disease, nor any proven ways to prevent its onset. Treatment focuses on support and managing symptoms. The condition is ultimately fatal.
In Alzheimer’s disease, brain cells start to deteriorate. The body attempts to stop this process by producing a protein called amyloid. However, amyloid deposits build up in the brain, leading to further deterioration. These deposits of amyloid are referred to as "plaques" and cause the brain cells to shrivel up and form "tangles", which in turn lead to changes in the brain structure and cause the brain cells to die. The formation of plaques and tangles also prevents the production of some important brain chemicals, called neurotransmitters. Over time the loss of brain cells causes the brain to shrink.
There is no known cause for Alzheimer's disease but some researchers now believe that a combination of environmental and genetic risk factors triggers an abnormal biological process in the brain that, over decades, results in Alzheimer-type dementia. Identified risk factors for developing the condition include:
- Increasing age
- Down's syndrome
- History of a head injury
- Risk factors for blood vessel disease such as smoking
- Family history of Alzheimer's disease
- High blood pressure
- High cholesterol
- Insulin resistance.
There is some evidence of a slightly higher prevalence of Alzheimer's disease in females than males, but this may be a reflection of their longer life expectancy.
Research studies have indicated that that the following factors may play an important role in the development of the condition:
Genetic factors, such as the presence of, or changes to, certain genes.
Environmental factors, such as long term exposure to some environmental solvents eg: pesticides, glues and paints.
The role of autoimmune factors and certain viruses are also being studied.
Signs and symptoms
The degenerative changes that occur with Alzheimer's disease affect the areas of the brain that control thought, memory and language resulting in gradual signs and symptoms related to a person’s behaviour and mental function. Often, physical functions such as bowel and bladder control are also affected.
With Alzheimer’s disease there is great individual variability as to the nature of symptoms experienced and the speed at which deterioration occurs. The types of behaviour change and the length of time symptoms are present are different for each person. 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.
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
- Possibly 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 of urine / faeces
- 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. It is particularly difficult as the person’s condition deteriorates and they 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 that do remain, such as the senses of touch and hearing and the ability to respond to emotion.
There is a no single test to diagnose Alzheimer’s disease. Diagnosis involves a full assessment of medical and psychiatric history to rule out other possible causes. Therefore a variety of tests are required to obtain a conclusive diagnosis, which may include:
- 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 to check brain structure and function may be recommended. The different types of scans used may include CT scanning (computerised tomography) and MRI (magnetic resonance imaging).
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.
- Encouraging stimulating activities in order 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 regular routine to reduce confusion.
- Not smoking.
Medications such as sleeping tablets and tranquillisers may help to control symptoms such as sleeplessness and agitation. However they often cause increased confusion, so their use should be limited.
A group of medications called cholinesterase inhibitors have shown some effectiveness in slowing the progression of the condition in some people. These medications help prevent the breakdown of acetylcholine, a neurotransmitter responsible for memory. Cholinesterase inhibitor medications that are available in New Zealand include donepezil (Donepezil-Rex), rivastigmine (Exelon) and galantamine (Reminyl).
More recently, another drug - memantine (Ebixa) - has become available in New Zealand. Memantine works in a different way to the cholinesterase inhibitors, aiming to prevent the entry of an excess amount of calcium into brain cells. Higher than normal levels of calcium in the brain cells causes damage to them and also prevents them from receiving signals from other brain cells.
Currently, donepezil is the only drug that is government-subsidised for the treatment of Alzheimer's disease.
Research continues into the development of other medications for the treatment of Alzheimer's disease. Medications being investigated include those that prevent the build up of amyloid deposits in the brain, as well as looking at the use of some anti-inflammatory and hormone medications. Research also continues into the use of alternative therapies such as anti-oxidants like Vitamin E, selenium and some herbal extracts (ginko baloba in particular).
Prevention / risk reduction
There are no proven ways to prevent the development of Alzheimer's disease. However, there is epidemiological evidence to suggest that leading 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, and has the added benefit of lowering cardiovascular disease and diabetes risk. For more diet information, refer to our Healthy heart diet
Alzheimer's New Zealand (National Office)
PO Box 14768
Freephone: 0800 004 001
Alzheimer Society of Canada (2012) Stages of Alzheimer's Disease (what happens). Toronto www.alzheimer.ca/en/About-dementia/Alzheimer-s-disease/Stages-of-Alzheimer-s-disease
Alzheimer Society of Canada (2012) Alzheimer's disease research. Toronto. www.alzheimer.ca/en/Research/Alzheimer-s-disease-research
Alzheimer’s Disease International (2012) Drug Treatments. London. www.alz.co.uk/caring/drug-treatments
Alzheimers New Zealand (2010) Alzheimer's disease (PDF). Wellington. www.alzheimers.org.nz/files/regional/northland/Info_sheet_1_Alzheimers_Disease.pdf
Anderson, H.S. (2013). Alzheimer's Deisease. Medscape Reference: Drugs, Disease & Procedures. WEebMD LLC. http://emedicine.medscape.com/article/1134817-overview.
Everybody (2012) Alzheimer’s Disease. Auckland: MIMS (NZ) Ltd www.everybody.co.nz/page-febde697-2e4d-4d0b-9389-02c8759a9493.aspx
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 – 14 May 2013