Alzheimer's disease is a progressive, degenerative neurological disorder, meaning that the disorder gets worse over time. Alzheimer's disease is the most common cause of dementia among people over the age of 65 and it is thought that up to 4.5 million people have Alzheimer's disease, according to the National Institutes of Health (NIH). Five percent of people aged 65 to 74 and roughly 35 to 50 percent of people aged over 85 have the disorder, according to the National Institute of Neurological Disorders and Stroke (NINDS). However, despite the high prevalence of Alzheimer's disease among elderly people, Alzheimer's disease is not a normal part of aging.
Alzheimer's disease occurs when neurons in the brain die or break their connections with other neurons. This occurs because people with Alzheimer's disease experience atrophy of a part of the brain called the hippocampus. The hippocampus produces a neurotransmitter called acetylcholine. This chemical carries electrical signals from one neuron to another and is essential for memory, judgment and learning. In people with Alzheimer's disease, the cells that produce acetylcholine are damaged or killed and levels of the chemical gradually decline in the brain. This means that the electrical signals are not transmitted effectively from one neuron to another, causing the breakdown of neuron connections and the gradual atrophy of other parts of the brain.
The symptoms of Alzheimer's disease reflect where neuron connections are broken. For example, memory loss, a common early stage symptom, is caused by the disruption of neurons in the temporal and parietal lobes, which are associated with memory. Language problems, on the other hand, are thought to be caused by the disruption of the large networks of neurons that are associated with understanding and producing language.
People with Alzheimer's disease also have abnormal lesions called beta-amyloid plaques and neurofibrillary tangles. Beta-amyloid plaques are sticky pieces of protein and other matter than surround the neurons. Neurofibrillary tangles are twisted fibers also made from protein that build up inside the neurons. These plaques and tangles work together to disrupt brain function and are known to increase in quantity as the Alzheimer's disease progresses.
Certain factors of brain dysfunction in Alzheimer's disease are known, but much about the disease is unknown. The known factors include the onset and progress of dementia in patients and the presence of the plaques and tangles in their brains, which may be detected at autopsy. But specific causes remain unknown and the role of plaques and tangles, as either cause or result, are not well understood. It is thought that these amyloid plaques form very early in the disease stage and set of a cascade of inflammation and cell death throughout the affected portions of the brain. However, no one knows why the amyloid plaques form. Similarly, very little is understood about the tangles in the brain, or how they relate to the plaques.
The symptoms of Alzheimer's disease usually begin to appear around the age of 60. However, some people develop a condition called early-onset Alzheimer's disease as early as their 20s. Early-onset Alzheimer's disease is thought to be caused by a genetic disorder.
Alzheimer's disease can progress slowly or rapidly, depending on the individual. Patients generally live for an average of eight years after they are diagnosed with Alzheimer's disease, although they may live for up to 20 years. During the final stages of the disease, most patients require constant supervision and help performing basic self-care tasks such as bathing and feeding.
Most people do not die as a direct result of Alzheimer's disease. Instead, people with Alzheimer's disease are more likely to contract other medical conditions that can be fatal. Many people with Alzheimer's disease die from aspiration pneumonia (pneumonia caused by breathing in vomit or other fluids) because of the reduced ability to swallow in the later stages of the disease. In 2004, the most recent year for which figures are available, Alzheimer's disease was the fifth leading cause of death among people over 65 and the seventh leading cause of death overall, according to the Centers for Disease Control and Prevention (CDC).
Women are more commonly diagnosed with Alzheimer's disease than men, although this may be because women tend to live longer than men.
Although Alzheimer's disease is the leading cause of dementia, other conditions may cause dementia, including stroke, brain tumors and infections.
Alzheimer’s disease is caused by the progressive destruction of neurons in the brain. However, physicians may refer to “stages” of Alzheimer's disease when diagnosing or monitoring the progress of the disease in a patient. These stages are commonly accepted patterns of progression that physicians have witnessed in people with the disease. However, it is important to remember that the stages are used as a rough approximation of the progress of the disease and that different staging frameworks may be used by different physicians. An example of a staging framework may be:
At this stage, the symptoms of Alzheimer's disease are mild and may include problems remembering recent events and a tendency to be more withdrawn than usual. These symptoms may be noticeable by friends and family. At this stage, patients are usually able to live independently and compensate for many of the symptoms they may be experiencing.
By this stage, the symptoms of Alzheimer's disease may become more pronounced and the patient may require assistance with some activities of daily living, such as dressing, eating and using the bathroom. Patients may be unable to remember essential information about themselves such as their current address or telephone number. They may also be confused about where they are and what day, month or year it is. At this stage, patients may or may not have a problem remembering their own name or the names of their family members. The patient may begin to experience signs of personality and behavioral changes.
At this stage of the disease, symptoms become severe and the patient usually requires constant assistance for the majority of daily functions. Patients may have lost the ability to use or understand language. They may also be unable to recognize members of their family or remember their own name. They may have lost many aspects of motor function, requiring assistance to sit, walk and support their head. Swallowing may become impaired, increasing the risk of choking or developing pneumonia.
Although scientists are unsure of the initial cause of Alzheimer's disease, it is known that the symptoms of Alzheimer's disease are caused by the disconnection and death of neurons in the brain. Based on what scientists understand about Alzheimer's disease, the following have been established as risk factors for the disease:
By far the greatest risk factor for developing Alzheimer's disease is age. The number of people with Alzheimer's disease doubles every five years after the age of 65, according to the National Institute of Neurological Disorders and Stroke (NINDS).
People who have a sibling or parent with Alzheimer's disease are more likely to develop the disease themselves. This risk is greater if more than one member of the family has been diagnosed with Alzheimer's disease. Although the phenomenon is still being studied, it is thought to be related to a slight variation in the genes of certain people that makes them especially susceptible to the disease.
There is strong evidence that suggests that people who sustain serious head injury are more likely to develop Alzheimer's disease later in life. However, this link has not been firmly substantiated by medical research and is more commonly linked to other forms of dementia.
Although this is somewhat controversial, a number of lifestyle factors might play a role in the development of Alzheimer's. These include lack of exercise, lack of access to a social network, and lack of mentally stimulating activities. For example, numerous studies have shown that people with advanced degrees are less likely to develop Alzheimer's, possibly due to increased brain elasticity. In addition, there may be a link between obesity and the metabolic syndrome and Alzheimer's disease.
There have been some reports linking aluminum to an increased risk of developing Alzheimer's disease. Aluminum is a common element that is found naturally in the environment as well as in various household products. Although toxic levels of exposure to aluminum is known to cause some neurological symptoms, the role of aluminum in the development of Alzheimer's disease is not fully understood. Many experts believe that the risks associated with normal aluminum exposure are low.
Symptoms of Alzheimer's disease usually begin to appear around the age of 60. Alzheimer's disease is primarily marked by the onset and progression of dementia, a decline in mental function that may interfere with the ability to perform daily functions. Dementia involves both cognitive (intellectual) and psychiatric symptoms. Cognitive symptoms of Alzheimer's disease may include:
Memory can be categorized in two ways: short-term memory and long-term memory. Short-term memory is the ability to remember events that occurred a short time ago or to recall things that were recently learned (such as a person’s telephone number or the name of a restaurant). Short-term memory is stored in the temporal lobe in the brain. This is often the first part of the brain to be affected by Alzheimer's disease. Long-term memory is the ability to remember events that happened in the distant past or recall things that were learned earlier in life. Long-term memory is stored in both the temporal and parietal lobes of the brain. It is usually lost during later stages of the disease.
Loss of the ability to use and understand language. This is usually the result of neuron damage to the left side of the brain, which is associated with language. People with Alzheimer's disease may forget words and have difficulty communicating with others (extensive aphasia). They may also have problems understanding spoken or written words (receptive aphasia).
Loss of ability to recognize familiar people, places or things. It is usually the result of neuron damage in the occipital or parietal lobes. Agnosia also involves an inability to interpret signals from the body, such as when the bladder is full or pain signals that imply serious conditions (e.g., chest pain).
An impaired ability to carry out motor activities, even when motor functioning remains intact.
The psychiatric symptoms of dementia are most likely caused by imbalances in brain chemistry and are often the most distressing for the patient and the patient’s family and friends. Some people with Alzheimer's disease do not experience all or any of these symptoms. Psychiatric symptoms may be treated using antipsychotic, anti-anxiety or anti-depressant medication. They may include:
This is often a marker of the early stages of Alzheimer's disease. Changes in personality may include irritability, apathy and a tendency to withdraw from the company of friends and relatives.
Most people with Alzheimer's disease show some signs of depression throughout the progression of the disease. This may be mistaken as a reflection of recent events, especially if the person has recently lost a loved one. The development of depression is a risk factor for further psychiatric symptoms, including hallucinations and delusions.
These usually occur during the middle stage of Alzheimer's disease. Hallucinations may be visual or aural and may be exacerbated by loss of hearing or sight. Although people with Alzheimer's disease may sometimes be aware that the hallucination is false, in later stages of the disease they may have a strongly held belief in things that are not real. This is called delusion. A significant percentage of Alzheimer's patients suffer from paranoid delusions, in which they imagine their home has been invaded, that personal items have been stolen, or that loved ones have been replaced by impostors. These can be extremely upsetting to both care-givers and Alzheimer's patients.
People with Alzheimer's disease may also experience apraxia, which is an inability to perform tasks on demand. This symptom occurs when the neuron connections in the parietal lobe of the brain are affected. The first element that is affected by Alzheimer's disease is usually complex motor skills such as those required to perform most daily tasks (e.g., writing, brushing hair). Next, a person may be unable to complete tasks that were learned during childhood, such as tying a shoelace or brushing teeth. The last element of motor function to be lost is instinctive motor function such as chewing, swallowing or walking.
Certain symptoms of Alzheimer's disease may be mistaken for the changes in memory function and mild confusion that people may experience as they get older. Most older people occasionally misplace items or forget the exact details of something that happened in the past. These minor changes are different from Alzheimer's disease because Alzheimer's disease progressively gets worse until the person is unable to function without a permanent caregiver.
There is no definitive diagnostic test for Alzheimer's disease and diagnosis can often be delayed because the early symptoms (e.g., forgetfulness, mild confusion) may be similar to some of the signs of normal aging. It may be especially difficult to obtain a diagnosis if the patient is under 65 and experiencing early-onset Alzheimer's disease because early symptoms may be similar to those experienced by people under extreme stress or people who are depressed. An important aspect for physicians is to assess whether the symptoms the patient is experiencing could be due to another cause, such as vitamin deficiency, dehydration or a side effect of medication the patient is taking. Patients may be referred to a neurologist, psychiatrist or psychologist following the presentation of symptoms.
If a physician suspects Alzheimer's disease, diagnosis will begin with a physical examination and a medical history. Patients or their caregivers are encouraged to keep a log of symptoms to report to the physician. A physician may also ask family members or close friends about the nature of the patient’s symptoms. During the medical history, the physician may ask questions related to the patient’s dietary habits and use of alcohol and/or drugs in order to rule out other potential causes of dementia. During the physical examination, the physician may assess neurological function by testing the patient’s reflexes, balance and coordination.
A physician may also use an electroencephalogram (EEG). An EEG is a test in which electrodes are placed on a patient’s head and information about the brain’s electrical activity is recorded as a series of brain waves. This type of test can be used to rule out other causes of dementia, such as infections or metabolic problems.
A physician may conduct a mental status examination to assess the stage of dementia that a patient may have reached. During the exam, the physician may ask the patient a variety of questions aimed at testing the patient’s awareness of surroundings, problem solving skills and memory skills.
- Situational questions such as “What year is it?” or “What is the address of this office?”
- Remembering and recalling a short list of items (e.g., a ball, a pencil, a dog)
- Counting backward or spelling a word backward
- Naming familiar objects in the room as the physician points to them
- Following simple instructions or writing a simple sentence
This test can also be used after diagnosis to evaluate the progression of Alzheimer's disease in the patient.
In diagnosing Alzheimer's disease, a physician may also recommend imaging tests, such as magnetic resonance imaging (MRI), computed tomography (CT) and positron emission tomography (PET) scans. Imaging tests can be used to identify other potential causes of dementia such as tumors, evidence of strokes or damage from head trauma. Imaging tests can also be used to measure the brain, which shrinks over time in people with Alzheimer's disease as parts of the brain atrophy. However, imaging tests cannot identify the microscopic “plaques” and “tangles” in the brain characteristic of Alzheimer's disease because of their small size.
In some cases, blood tests, urine tests and spinal taps may be performed to rule out other conditions that may have symptoms similar to Alzheimer’s disease.
At this time, there is no cure for Alzheimer's disease, nor is there any way of slowing the progress of the disease. However, there are treatment options available that can minimize or stabilize patients’ symptoms, and in some cases delay the necessity of nursing home care.
A physician may prescribe medication for cognitive symptoms (e.g., memory loss, loss of language function). Some Alzheimer's medications are designed to maintain the levels of a brain chemical called acetylcholine. Acetylcholine is a neurotransmitter, which means that it carries electrical signals from one neuron to another. This chemical is essential for memory, judgment and learning. Medications that delay the breakdown of acetylcholine are called cholinesterase inhibitors. These medications may not be as effective among patients with advanced disease. Other Alzheimer's medications regulate the function of another neurotransmitter, glutamate, which is important for learning and memory. Studies have shown that these two medications — the cholinesterase inhibitors combined with glutamate receptor blockers — may be more effective than either medication used alone with severe disease.
It is thought that Alzheimer's disease may be caused or exacerbated by the presence of free radicals, a type of molecule that can damage cells and has been known to cause cancer and other medical conditions. Some physicians might recommend vitamin E, an antioxidant, used in combination with other antioxidants to reduce oxidative damage to the brain.
Behavioral or psychiatric symptoms may first be treated with methods other than medications. This usually includes identifying the potential trigger for the symptoms and attempting to resolve it. Many times this involves making adjustments to the environment that the patient lives in, for example simplifying the environment or increasing the time between stimulating events (e.g., bath-time, getting dressed). A few studies have also examined the use of aromatherapy to reduce agitation and dementia. Other possible interventions include massage therapy, exercise, and even pet therapy.
In addition to non-drug methods, a physician may recommend certain medications to control behavioral or psychiatric symptoms. It is important that these medications be used with caution because people with dementia are more likely to experience severe side effects than most people.
In recent years, numerous complementary and alternative therapies and supplements have been promoted for Alzheimer’s disease and its symptoms. However, in most cases, these treatments have not been studied in clinical trials and have not been approved by the Food and Drug Administration (FDA) for use by Alzheimer's patients. Many alternative treatments are marketed as dietary supplements, which only have to prove they are safe. They are not tested for effectiveness in treating a disorder.
- Coenzyme Q10. An antioxidant that occurs naturally in the body and may help reduce the presence of free radicals.
- Ginkgo biloba. An herb that is claimed by some to improve memory. The National Center for Complementary and Alternative Medicine (NCCAM) is conducting a long-term study on the use of ginkgo biloba in healthy elderly people to prevent the onset of dementia.
- Huperzine A. An herbal supplement that may function in a similar way as cholinesterase inhibitors.
- Phosphatidylserine. A type of lipid (fat) that may protect nerve cells from degenerating.
- Omega-3 fatty acids. These fatty acids are already known to be protective of the heart, and populations that consume large amounts of omega-3 fatty acids such as those found in fish oil appear to have a reduced incidence of Alzheimer's disease. However, clinical trials have not shown any affect on the course of the disease once symptoms have begun to show. Rather, it appears that omega-3 fatty acids might have a protective, long-term effect.
It is important to discuss the use of alternative treatment methods with a physician before they are started. Some alternative remedies could interact with prescribed medication or lead to more serious health complaints.
There is much that is unknown about Alzheimer's disease, including the cause or causes and how to slow or stop its progress. Because of this, Alzheimer's disease is a difficult disease to prevent.
There is some evidence that indicates that people who sustain severe head injuries are more likely to develop Alzheimer's disease later in life. For this reason, it is important to always wear a seatbelt while traveling in a car and to wear protective headgear while operating a motorcycle or bicycle, or while playing contact sports.
Other studies have shown that oxidative stress, the process of cell damage by free radicals, contributes to the risk of developing Alzheimer's disease. Oxidative stress can be prevented by consuming foods that are high in antioxidants, such as olive oil, fish and fresh fruit and vegetables. It can also be prevented by taking supplements of vitamin A, C and E, although a physician should always be consulted before starting any supplements.
It is also becoming clear that maintaining brain health by remaining physically and mentally active throughout life, especially in later life, is important. This includes controlling weight, blood pressure and cholesterol levels. It is not known whether physical and mental activity directly reduce the risk of developing Alzheimer's disease, but scientists agree that it appears reasonable that keeping the body and mind healthy is beneficial on many levels.
Alzheimer's disease can be overwhelming for both the patient and the patient’s loved ones. In the early stages of Alzheimer's disease, patients and their loved ones may become frustrated with memory loss or the inability to complete simple tasks. This may result in depression or anger. As the disease progresses, patients usually experience more substantial dementia that may affect their ability to perform self-care tasks such as bathing and dressing and may require professional care in a nursing home.
Alzheimer's disease also presents certain safety issues. For example, people with Alzheimer's disease are more likely to be injured around the home. Injuries may be caused by falls that occur when the parts of the brain responsible for balance and coordination are affected. Additionally, the memory loss that is associated with Alzheimer's disease may make it unsafe for patients to cook (especially over a direct heat source), drive and otherwise live independently. It may be necessary to take certain safety precautions in the home, such as installing railings around the bath or shower and setting the water temperature to a lower level to avoid scalding.
Family support is an essential aspect of Alzheimer's care and treatment. It is important that loved ones understand the patient’s limitations and adjust their behavior and communication strategies accordingly. As the disease progresses, patients may exhibit strange behavior such as aggression or forgetting the names of immediate relatives. This can be a traumatic experience for close friends and family. In some cases, individual or group therapy is beneficial for those coping with the consequences of Alzheimer's disease in a close friend or family member.
Preparing questions in advance can help patients have more meaningful discussions with healthcare professionals regarding their condition. Patients or their caregivers may wish to ask their doctor the following Alzheimer's disease-related questions:
- Am I at risk for Alzheimer's disease?
- How do you know that my symptoms are caused by Alzheimer's disease?
- Can I tell if my parent’s symptoms are caused by Alzheimer’s disease or just aging?
- What tests will you use to diagnose Alzheimer's disease?
- At what stage is my Alzheimer's disease?
- What kind of medication will you prescribe for my Alzheimer's disease?
- What side effects should I look out for?
- Are there any over-the-counter medications that I should avoid?
- Will other chronic medical conditions such as heart disease or arthritis be complicated by Alzheimer’s disease?
- Am I going to have to stop driving?
- Will I have to move out of my home?
- Is there anything I can do to prevent Alzheimer's disease?
- If one of my parents had Alzheimer’s disease, am I at greater risk for it?
- What specific dangers should I guard for in a parent with Alzheimer’s disease?
- Can you recommend a support group or other services available for caregivers and family members of Alzheimer’s patients?
Complications of Alzheimer's disease include decreased resistance to infections, especially pneumonia and meningitis, and seizures. Recurrent falls are commonly seen in later stages.
Early diagnosis affords individuals with an opportunity to plan retirement from work, arrange for management of their finances, and discuss the management of future medical problems. Skilled, supportive care can improve the quality of the individual's life. Affected persons eventually may become bedridden and unable to care for themselves and, in advanced stages of the disease, may require care in a nursing facility. In the final stages, individuals with Alzheimer's disease may be unable to communicate or feed themselves and have bowel and bladder incontinence. Alzheimer's disease is ultimately fatal.
Differential diagnoses may include vitamin B12 deficiency, hypothyroidism, depression, delirium, an adverse reaction to prescribed medications, chronic subdural hematoma, Pick's disease, Creutzfeldt-Jakob disease, tumors, hydrocephalus, or multiple strokes.
Neurologist, neuropsychologist, audiologist and radiologist.