What distinguishes Alzheimer's from other types of dementia? Here's how experts make a diagnosis
Dementia is a general term that describes a significant loss of
intellectual abilities, including memory, the ability to reason, and
other cognitive and behavioral changes that can interfere with daily
life. While a number of health conditions can lead to dementia and
related brain deterioration, the most common cause is Alzheimer's disease,
which according to one recent study sponsored by the National Institute
on Aging, now accounts for as much as 70 percent of all cases of
dementia in people 71 and older.
Alzheimer's disease strikes about 5 percent of all people between the ages of 65 and 74. Some forms of dementia can be treated, and some symptoms may even be reversed, especially if caught early. Most types of dementia, however, including Alzheimer's, become progressively worse and are, as of now, incurable.
Symptoms of Dementia
While dementia presents itself differently from individual to individual, common symptoms include:
Since the only way to definitively confirm the presence of Alzheimer's disease is by looking at changes in brain tissue, which can usually only be examined after death during an autopsy, any diagnosis of Alzheimer's is essentially an educated guess. But, despite the challenge of sorting out Alzheimer's from other causes of dementia, experts at the National Institute on Aging estimate that doctors at specialized centers can now diagnose Alzheimer's with 90 percent accuracy. Some diagnostic tools doctors use for Alzheimer's include:
While Alzheimer's disease is the most common form of dementia, affecting an estimated 4.5 million Americans, other diseases or traumas can also lead to neurological dysfunction. In some cases, different types of dementia can coexist in one patient. Some examples of non-Alzheimer's dementia include:
Vascular dementia. Caused by impaired blood flow to parts of the brain, this form of dementia can occur when narrowed blood vessels provide less oxygen than necessary to the brain tissue, after a major stroke, brain hemorrhage, or a period of catastrophically low blood pressure, or due to other artery-damaging conditions such as systemic lupus erythematosus or temporal arteritis. Onset of symptoms can be sudden (such as following a major stroke) or can progress gradually after a series of smaller strokes (called multi-infarct dementia).
Dementia with Lewy bodies (DLB). Patients with this
type of dementia have abnormal clumps of protein in their brains. DLB
symptoms include progressive cognitive decline with lethargy, visual
hallucinations, and loss of movement and motor control. Lewy bodies have
also been found in people with Parkinson's disease and Alzheimer's,
suggesting a connection among the three conditions.
Frontotemporal dementia (including Pick's disease). This rare disorder is sometimes characterized by the shrinking of areas in the front and sides of the brain (which can be detected with a brain-imaging scan). Because these areas of the brain regulate social behavior and judgment, this type of dementia is often characterized by sudden personality changes and inappropriate behavior, as well as by problems with understanding and using language.
Huntington's disease. People with this fatal genetic disorder develop involuntary movements, such as twitches and spasms, difficulty with motor tasks, mood swings, intellectual impairment, personality changes, and eventually severe dementia.
Parkinson's disease. Early symptoms of Parkinson's include stiffness of the limbs, tremors, speech impairment, and difficulty with walking and muscle control. Dementia can often occur as a secondary symptom in the later stages of the disease.
Related reactions. Some other situations that can cause dementia-like symptoms include reactions to medications, thyroid problems, infections in the brain, alcoholism, HIV-related dementia, and even vitamin deficiencies.
The Future of Alzheimer's Diagnosis
Early and accurate diagnosis offers the best chance of treating Alzheimer's symptoms and helps to give patients and their families more time to evaluate and discuss their treatment and care options. For this reason, doctors are working on ways to improve early detection. Some of the latest efforts include:
Alzheimer's disease strikes about 5 percent of all people between the ages of 65 and 74. Some forms of dementia can be treated, and some symptoms may even be reversed, especially if caught early. Most types of dementia, however, including Alzheimer's, become progressively worse and are, as of now, incurable.
Symptoms of Dementia
While dementia presents itself differently from individual to individual, common symptoms include:
- Memory loss that increases over time
- Language problems, such as difficulty finding words or understanding spoken or written communication
- Disorientation, eventually extending to familiar places
- Persistent confusion, including about the date or time of day
- Face-recognition issues, in time even with familiar people
- Lack of self-regard, including neglect of personal safety or hygiene
- Inability to do routine tasks, such as pay bills or shop for groceries
- Erratic behavioral and psychological changes, such as paranoia, hallucinations, depression, temper tantrums, or insomnia
Since the only way to definitively confirm the presence of Alzheimer's disease is by looking at changes in brain tissue, which can usually only be examined after death during an autopsy, any diagnosis of Alzheimer's is essentially an educated guess. But, despite the challenge of sorting out Alzheimer's from other causes of dementia, experts at the National Institute on Aging estimate that doctors at specialized centers can now diagnose Alzheimer's with 90 percent accuracy. Some diagnostic tools doctors use for Alzheimer's include:
- Patient evaluation, including an overview of their general health, previous medical conditions, and their ability to conduct daily activities
- Cognitive tests to measure memory, problem solving, and language skills
- Lab tests of blood, urine, and spinal fluid
- Brains scans
While Alzheimer's disease is the most common form of dementia, affecting an estimated 4.5 million Americans, other diseases or traumas can also lead to neurological dysfunction. In some cases, different types of dementia can coexist in one patient. Some examples of non-Alzheimer's dementia include:
Vascular dementia. Caused by impaired blood flow to parts of the brain, this form of dementia can occur when narrowed blood vessels provide less oxygen than necessary to the brain tissue, after a major stroke, brain hemorrhage, or a period of catastrophically low blood pressure, or due to other artery-damaging conditions such as systemic lupus erythematosus or temporal arteritis. Onset of symptoms can be sudden (such as following a major stroke) or can progress gradually after a series of smaller strokes (called multi-infarct dementia).
Frontotemporal dementia (including Pick's disease). This rare disorder is sometimes characterized by the shrinking of areas in the front and sides of the brain (which can be detected with a brain-imaging scan). Because these areas of the brain regulate social behavior and judgment, this type of dementia is often characterized by sudden personality changes and inappropriate behavior, as well as by problems with understanding and using language.
Huntington's disease. People with this fatal genetic disorder develop involuntary movements, such as twitches and spasms, difficulty with motor tasks, mood swings, intellectual impairment, personality changes, and eventually severe dementia.
Parkinson's disease. Early symptoms of Parkinson's include stiffness of the limbs, tremors, speech impairment, and difficulty with walking and muscle control. Dementia can often occur as a secondary symptom in the later stages of the disease.
Related reactions. Some other situations that can cause dementia-like symptoms include reactions to medications, thyroid problems, infections in the brain, alcoholism, HIV-related dementia, and even vitamin deficiencies.
The Future of Alzheimer's Diagnosis
Early and accurate diagnosis offers the best chance of treating Alzheimer's symptoms and helps to give patients and their families more time to evaluate and discuss their treatment and care options. For this reason, doctors are working on ways to improve early detection. Some of the latest efforts include:
- Memory tests. Researchers are working to improve standardized memory and recall tests to better track changes that might indicate early Alzheimer's and even predict which individuals are at higher risk of developing the disease in the future.
- Tissue comparisons. Studies are examining the relationship between early damage to brain tissue and later development of Alzheimer's.
- Blood tests. Researchers are looking for ways to identify changes in blood chemistry that could one day lead to blood tests or other simple tools to identify individuals at risk for Alzheimer's.
- Imaging scans. Doctors are looking at ways to use neuroimaging, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), to one day help identify individuals who are in the early stages of the disease, even before they develop symptoms.
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