Dementia is a decline in a person's brain functions, usually memory and thinking, caused by damage…
- Alzheimer's disease is a condition in which cells in the brain gradually degenerate and die.
- Alzheimer's disease causes a person to gradually lose their ability to think clearly, remember, communicate and carry out routine tasks.
- Unfortunately, there is no known cure for Alzheimer's disease, but its progression can be slowed by treatment. The earlier that treatment starts, the better the outcomes.
What is Alzheimer's disease?
Alzheimer's disease is a degenerative condition of the brain that causes problems with memory, thinking, language and behaviour.
Alzheimer's disease is the most common form of dementia. Dementia is not a single condition, but a collection of symptoms that are caused by brain disorders.
- Is a leading cause of disability in older people (over 65 years of age), and;
- Is more common in women than men.
Alzheimer's disease is caused by damage to brain cells called neurons. Neurons transmit the electrical nerve signals that carry information throughout the brain and body. The disease disrupts the neurons' ability to work properly, leading to loss of these signals and of information within the brain.
In Alzheimer's disease, the brain contains abnormal amounts of two proteins - amyloid and tau - as well as lower levels of the chemical messenger acetylcholine.
In people with Alzheimer's disease, fragments of the amyloid protein form sticky plaques, which build up outside the neurons. This can destroy neurons that produce acetylcholine. The tau protein has been found to build up inside the neurons.
It is thought that the accumulation of these proteins both inside and outside the neurons impairs the normal function of neurons, eventually leading to death of these brain cells.
Alzheimer's disease follows a gradual course; in its early stages, the brain is able to compensate for the damage to neurons. However, as the condition progresses, the damage spreads to other parts of the brain, and the symptoms become increasingly apparent.
The symptoms of Alzheimer's disease can be divided into three main stages:
Mild Alzheimer's disease
People at this stage of Alzheimer's disease may:
- Be less willing and able to try new things and adapt to change;
- Become lost in familiar surroundings;
- Forget the names of known objects and places;
- Find it harder to make decisions;
- Have difficulty managing finances, carrying out routine tasks, and;
- Show changes in their personality and moods.
Moderate Alzheimer's disease
People at this stage of Alzheimer's disease may:
- Become lost easily;
- Neglect hygiene and eating;
- Show increasing confusion and disorientation;
- Experience hallucinations and delusions, and;
- Experience rapid mood swings, depression and anxiety.
Severe Alzheimer's disease
People at this stage of Alzheimer's disease may:
- Experience faecal incontinence or urinary incontinence;
- Fail to recognise everyday objects;
- Not be able to recognise friends and family;
- Have difficulty eating, swallowing and speaking, and;
- Experience significant memory problems.
Risk factors for Alzheimer's disease include:
- Advancing age - the likelihood of developing Alzheimer's disease doubles every 5.5 years from 65-85 years of age;
- A family history of Alzheimer's disease;
- Heart disease;
- High cholesterol;
- Having a specific type of gene known as apoE-e4;
- Head trauma;
- Gender - women are affected more frequently than men, and;
- Having Down syndrome. People with Down syndrome experience premature ageing and may be up to five times more likely to develop Alzheimer's disease.
The three main types of Alzheimer's disease can be described as follows:
This is the most common form, accounting for about 90% of cases. This type may or may not be inherited, and usually occurs in people over the age of 65 years.
This is a less common form, accounting for less than one in 10 (10%) of cases. This type may be linked to a specific genetic defect and usually occurs in people under the age of 65. People with Down syndrome are especially at risk of developing this type.
This is an extremely rare type, accounting for less than one in 100 (1%) of cases. This type is entirely inherited, and usually occurs in people under the age of 65 (often under the age of 50).
Signs and symptoms
Alzheimer's disease generally progresses slowly, so the symptoms may initially not be very noticeable. As the disease progresses, the symptoms become more noticeable and may interfere with daily life.
Some of the more common symptoms early on may include:
- Short-term memory loss, which is persistent and frequent;
- Language difficulties, such as struggling to find the right word or not being able to understand conversations;
- Disorientation, even in places the person knows well;
- Problems with carrying out familiar tasks;
- Rapid and unpredictable changes in mood;
- Decreased motivation or interest in hobbies, and;
- Sleep changes, in the pattern or amount of sleep.
Methods for diagnosis
The early and correct diagnosis of Alzheimer's disease is important, as it:
- Allows timely and appropriate treatment for other (curable) disorders that might be the cause of symptoms that mimick those of Alzheimer's disease;
- Allows more time to plan for future needs, and;
- Enables the possible use of medications that are most beneficial in earlier stages of Alzheimer's disease.
Patient history and cognitive testing
To diagnose Alzheimer's disease, your doctor may:
- Obtain a complete patient history to help assess past and present health problems;
- Obtain a complete family history, and;
- Perform cognitive testing - to assess problem solving, counting skills, memory and attention span. This testing can help identify whether current memory and thinking abilities no longer match with a former level of function, and which areas of the brain may be affected.
Blood tests may be used to exclude other, potentially reversible, conditions that may be mimicking Alzheimer's disease.
Brain imaging, including computerised tomography (CT) and magnetic resonance imaging (MRI) scans may be used in the diagnosis of Alzheimer's disease. These scans provide different kinds of images of the brain. The scans:
- Help identify other causes of dementia including haemorrhages, tumours or stroke;
- Distinguish between types of diseases causing the brain degeneration, and;
- Establish a baseline of degeneration.
A new imaging technique, a version of a positron emission tomography (PET) scan, has been developed that may identify areas and amounts of amyloid plaques formation. This test may help increase the accuracy of diagnosis but is not widely available as yet.
Types of treatment
As there is currently no cure for Alzheimer's disease, the goals of treatment are to slow the progression of the disease, manage its symptoms, and set up a care plan to ensure that a person with Alzheimer's disease can continue to live a comfortable life.
Most people with Alzheimer's disease can remain in their homes as the disease progresses, as long as support is available. Carer support is crucial to the management of a comfortable life.
The first step in supportive treatment is to evaluate the self-care needs of the person with Alzheimer's disease. Then, simple changes can be made to the home environment to ensure that they are safe while at home, when driving or when out in the wider community.
Restoring levels of the neurotransmitter acetylcholine is one of the strategies currently used in treating Alzheimer's disease. Medications such as donepezil, galantamine and rivastigmine improve cognition and slow the rate of functional decline. They show the most benefit if used in the earlier stages of disease.
A beneficial effect, if any, may be observed within 3-6 months of starting the treatment. Side effects of these medications may include stomach upset, vomiting, muscle cramps and fatigue.
N-methyl-D-aspartate receptor (NMDA) antagonist
Memantine belongs to a class of medications called NMDA antagonists. It does not slow the progression of Alzheimer's disease, but can improve symptoms for people with moderate to severe Alzheimer's disease. It may be used at the later stages of Alzheimer's disease.
It is very common for people with Alzheimer's disease to experience depression. Depression can adversely affect cognitive function and add to the stress of carers.
There are many classes of antidepressants used to treat depression, but selective serotonin reuptake inhibitors (SSRIs) are usually the preferred treatment for depression associated with Alzheimer's disease. Sertraline, citalopram and escitalopram are some of the SSRIs considered as first-line treatment for depression associated with Alzheimer's disease.
Medication dosage might require adjustments over 1-2 months until the target dose has been reached.
As with most medications, antidepressants may have side effects. Some of the more common side effects include nausea, dizziness, fatigue and sexual dysfunction. There may be more serious side effects if they are taken in combination with other medications, herbal remedies, or alcohol.
There is a very rare risk of antidepressants causing or increasing suicidal thoughts. This risk is at its greatest during the first weeks of commencing treatment, or when the dosage is adjusted. Your doctor can advise you on ways to manage these changes.
People with Alzheimer's disease may experience anxiety, agitation and psychosis (hallucinations and delusions). Such symptoms may be treated with antipsychotic medication. However, the use of these medications is controversial, and may depend on the preferences of the treating doctor.
The antipsychotic drug risperidone has been shown to decrease the symptoms in some cases of Alzheimer's disease. However, there is some evidence that the use of antipsychotics may be associated with a higher risk of adverse outcomes. Common side effects of risperidone include agitation, anxiety, trembling, problems with urination, involuntary movements, weight gain and excessive thirst.
People with Alzheimer's disease may experience sleeping difficulties (insomnia). Simple measures that can help manage insomnia include limiting naps during the daytime, getting daily exercise and using bright light therapy. If such measures do not help with insomnia, medication to help with sleep may be advised.
People with Alzheimer's disease do not usually die from the disease itself, but from its complications. Some of the more serious complications include:
- Pneumonia - accidentally inhaling liquids and solids may increase the risk of aspiration pneumonia. Frequent bouts of pneumonia are more common in the late stages of Alzheimer's disease;
- Urinary tract infections (UTIs) - the urinary incontinence associated with later stages of Alzheimer's disease may require the insertion of a urinary catheter. Urinary catheters are known to increase the risk of contracting UTIs. If left untreated, UTIs can lead to more serious complications, such as sepsis or multi-organ failure;
- Falls - the impaired mobility and disorientation that comes at the later stages of Alzheimer's disease increases the likelihood of falls. Falls can cause complications such as fractures and head injury, and the lengthy immobilisation required for recovery can lead to further complications such as blood clots (DVTs) and pneumonia;
- Elder abuse - limited resources available to a carer may lead to neglect and isolation of the individual in their care, and;
- Weight loss - people with Alzheimer's disease may experience considerable weight loss, which may lead to malnutrition, an impaired immune system, loss of muscle tone and the loss of independence.
The natural course of Alzheimer's disease is a progressive decline to its terminal stages. Most cases progress over the course of 8-15 years. As the disease progresses, the symptoms become more apparent as do the self-care needs:
- In its earlier stages, the moderate memory decline means that people with Alzheimer's disease require help carrying out routine tasks, taking their medications and dealing with financial matters, and;
- In its later stages, the more severe impairment in memory, cognition and behaviour means that people with Alzheimer's disease require full daily assistance with activities including bathing, eating and dressing.
As the exact cause of Alzheimer's disease is currently unknown, there are no known ways to definitively prevent the condition, but there may be some ways of delaying the onset of dementia including:
- Maintaining a high level of fitness and heart health, which may reduce your risk of developing Alzheimer's disease;
- Quitting smoking;
- Avoiding excessive consumption of alcohol;
- Maintaining a healthy blood pressure, and;
- Eating a healthy diet.
There is some evidence suggesting that the rates of Alzheimer's disease are lower in people who remain mentally and physically active; however, there is currently no evidence to support the theory that 'brain training' games are effective in reducing the onset of Alzheimer's disease.