Alzheimer's disease, first described by the German neurologist Alois Alzheimer, is a physical disease affecting the brain. During the course of the disease, protein 'plaques' and 'tangles' develop in the structure of the brain, leading to the death of brain cells. People with Alzheimer's also have a shortage of some important chemicals in their brain. These chemicals are involved with the transmission of messages within the brain.
Alzheimer's disease is the most common cause of dementia. It is predicted there will be
more than 520,000 people in the UK with Alzheimer's disease in 2015. The term 'dementia' describes a set of symptoms which can include loss of memory, mood changes, and problems with communication and reasoning. These symptoms occur when the brain is damaged by certain diseases and conditions, including Alzheimer's disease. This factsheet outlines the symptoms and risk factors for Alzheimer's disease, and describes what treatments are currently available.
Causes
Like all types of dementia, Alzheimer's is caused by brain cell death. It is a neurodegenerative disease, which means there is progressive brain cell death that happens over a course of time.
The total brain size shrinks with Alzheimer's, the tissue has progressively fewer nerve cells and connections.
While they cannot be seen or tested in the living brain affected by Alzheimer's disease, postmortem/autopsy will always show tiny inclusions in the nerve tissue, called plaques and tangles:
- Plaques are found between the dying cells in the brain - from the build-up of a protein called beta-amyloid (you may hear the term "amyloid plaques").
- The tangles are within the brain neurons - from a disintegration of another protein, called tau.
This sort of change in brain nerves is also witnessed in other disorders, and researchers want to find out more than just that there are protein abnormalities - they also want to know how these develop so that a cure or prevention might be discovered.
Symptoms
At first, increasing forgetfulness or mild confusion may be the only symptoms of Alzheimer's disease that you notice. But over time, the disease robs you of more of your memory, especially recent memories. The rate at which symptoms worsen varies from person to person.
If you have Alzheimer's, you may be the first to notice that you're having unusual difficulty remembering things and organizing your thoughts. Or you may not recognize that anything is wrong, even when changes are noticeable to your family members, close friends or co-workers.
Brain changes associated with Alzheimer's disease lead to growing trouble with:
Memory
Everyone has occasional memory lapses. It's normal to lose track of where you put your keys or forget the name of an acquaintance. But the memory loss associated with Alzheimer's disease persists and worsens, affecting your ability to function at work and at home. People with Alzheimer's may:
- Repeat statements and questions over and over, not realizing that they've asked the question before
- Forget conversations, appointments or events, and not remember them later
- Routinely misplace possessions, often putting them in illogical locations
- Eventually forget the names of family members and everyday objects
Disorientation and Misinterpreting Spatial Relationships
People with Alzheimer's disease may lose their sense of what day it is, the season, where they are or even their current life circumstances. Alzheimer's may also disrupt your brain's ability to interpret what you see, making it difficult to understand your surroundings. Eventually, these problems may lead to getting lost in familiar places.
Speaking and Writing
Those with Alzheimer's may have trouble finding the right words to identify objects, express thoughts or take part in conversations. Over time, the ability to read and write also declines.
Thinking and Reasoning
Alzheimer's disease causes difficulty concentrating and thinking, especially about abstract concepts like numbers. It may be challenging to manage finances, balance checkbooks, and keep track of bills and pay them on time. These difficulties may progress to inability to recognize and deal with numbers.
Making Judgments and Decisions
Responding effectively to everyday problems, such as food burning on the stove or unexpected driving situations, becomes increasingly challenging.
Planning and Performing Familiar Tasks
Once-routine activities that require sequential steps, such as planning and cooking a meal or playing a favorite game, become a struggle as the disease progresses. Eventually, people with advanced Alzheimer's may forget how to perform basic tasks such as dressing and bathing.
Changes in Personality and Behavior
Brain changes that occur in Alzheimer's disease can affect the way you act and how you feel. People with Alzheimer's may experience:
- Depression
- Anxiety
- Social withdrawal
- Mood swings
- Distrust in others
- Irritability and aggressiveness
- Changes in sleeping habits
- Wandering
- Loss of inhibitions
- Delusions, such as believing something has been stolen
Many important skills are not lost until very late in the disease. These include the ability to read, dance and sing, enjoy old music, engage in crafts and hobbies, tell stories, and reminisce.
This is because information, skills and habits learned early in life are among the last abilities to be lost as the disease progresses. Capitalizing on these abilities can allow you to continue to have successes and maintain a high quality of life even when you are into the moderate phase of the disease.
Tests and Diagnosis
Alzheimer's disease is not simple to diagnose - there is no single test for it. For this reason, the first thing doctors do is to rule out other problems before confirming whether mental signs and symptoms are severe enough to be a kind of dementia or something else.
Doctors may:
- Take a history (ask about symptoms and daily activities)
- Do a physical examination to find any signs of, for example, a stroke, heart condition or kidney disease, and
- Check neurological function, e.g. by testing balance, senses and reflexes
Depending on what the doctor thinks could need checking, other diagnostics are:
- Sending off for tests of blood and urine samples
- Arranging brain scans (possibly including CT, MRI and EEG).
Again though, the above early tests are not for diagnosing Alzheimer's disease itself, but for ruling out other problems before starting to narrow down to dementia caused by AD. Central to this is checking memory loss and mental performance (cognitive testing).
Treatment
Alzheimer’s disease is complex, and it is unlikely that any one intervention will be found to delay, prevent, or cure it. That’s why current approaches in treatment and research focus on several different aspects, including helping people maintain mental function, managing behavioral symptoms, and slowing or delaying the symptoms of disease.
Maintaining Mental Function
Four medications are approved by the U.S. Food and Drug Administration to treat Alzheimer’s. Donepezil (Aricept®), rivastigmine (Exelon®), and galantamine (Razadyne®) are used to treat mild to moderate Alzheimer’s (donepezil can be used for severe Alzheimer’s as well). Memantine (Namenda®) is used to treat moderate to severe Alzheimer’s. These drugs work by regulating neurotransmitters (the chemicals that transmit messages between neurons). They may help maintain thinking, memory, and speaking skills, and help with certain behavioral problems. However, these drugs don’t change the underlying disease process, are effective for some but not all people, and may help only for a limited time.
Managing Behavioral Symptoms
Common behavioral symptoms of Alzheimer’s include sleeplessness, agitation, wandering, anxiety, anger, and depression. Scientists are learning why these symptoms occur and are studying new treatments—drug and non-drug—to manage them. Treating behavioral symptoms often makes people with Alzheimer’s more comfortable and makes their care easier for caregivers.
Slowing, Delaying, or Preventing Alzheimer’s Disease
Alzheimer’s disease research has developed to a point where scientists can look beyond treating symptoms to think about addressing underlying disease processes. In ongoing clinical trials, scientists are looking at many possible interventions, such as immunization therapy, cognitive training, physical activity, antioxidants, and the effects of cardiovascular and diabetes treatments.
Risk Factors
Some things are more commonly associated with Alzheimer's disease, not seen so often in people without the disorder. These factors may therefore have some direct connection. Some are preventable or modifiable factors (for example, reducing the risk of diabetes or heart disease may in turn cut the risk of dementia).
If researchers gain more understanding of the risk factors, or scientifically prove any "cause" relationships for Alzheimer's, this could help to find ways to prevent it or develop treatments.
Risk factors associated with Alzheimer's disease include:
- Unavoidable risk factors
- Age - the disorder is more likely in older people, and a greater proportion of over-85-year-olds have it than of over-65s.2
- Family history (inheritance of genes) - having Alzheimer's in the family is associated with higher risk. This is the second biggest risk factor after age.7
- Having a certain gene (the apolipoprotein E or APOE gene) puts a person, depending on their specific genetics, at three to eight times more risk than a person without the gene.6 Numerous other genes have been found to be associated with Alzheimer's disease, even recently (see developments below).7
- Being female (more women than men are affected).
Potentially Avoidable or Modifiable Factors
- Factors that increase blood vessel (vascular) risk, including diabetes, high cholesterol and high blood pressure. (These also increase the risk of stroke, which itself can lead to another type of dementia.)
- Low educational and occupational attainment.
- Prior head injury. (While a traumatic brain injury does not necessarily lead to Alzheimer's, some research links have been drawn, with increasing risk tied to the severity of trauma history.)8
- Sleep disorders (the breathing problem sleep apnea, for example).
- Estrogen hormone replacement therapy.
Prognosis
The early stages of Alzheimer's disease are difficult to diagnose. A definitive diagnosis is usually made once cognitive impairment compromises daily living activities, although the person may still be living independently. The symptoms will progress from mild cognitive problems, such as memory loss through increasing stages of cognitive and non-cognitive disturbances, eliminating any possibility of independent living, especially in the late stages of the disease.
Life expectancy of the population with the disease is reduced. The mean life expectancy following diagnosis is approximately seven years. Fewer than 3% of people live more than fourteen years. Disease features significantly associated with reduced survival are an increased severity of cognitive impairment, decreased functional level, history of falls, and disturbances in the neurological examination. Other coincident diseases such as heart problems, diabetes or history of alcohol abuse are also related with shortened survival. While the earlier the age at onset the higher the total survival years, life expectancy is particularly reduced when compared to the healthy population among those who are younger. Men have a less favourable survival prognosis than women.
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