Dementia (cont.)
How Is Dementia Diagnosed?
Doctors employ a number of strategies to diagnose dementia. It is important
that they rule out any treatable conditions, such as depression, normal pressure
hydrocephalus, or vitamin B12 deficiency, which can cause similar symptoms.
Early, accurate diagnosis of dementia is important for
patients and their families because it allows early treatment of symptoms. For
people with AD or other progressive dementias, early diagnosis may allow them to plan for the
future while they can still help to make decisions. These people also may
benefit from drug treatment.
The "gold standard" for diagnosing dementia, autopsy, does not help the
patient or caregivers. Therefore, doctors have devised a number of techniques to
help identify dementia with reasonable accuracy while the patient is still
alive.
Patient history
Doctors often begin their examination of a patient suspected of having
dementia by asking questions about the patient's history. For example, they may
ask how and when symptoms developed and about the patient's overall medical
condition. They also may try to evaluate the patient's emotional state, although
patients with dementia often may be unaware of or in denial about how their
disease is affecting them. Family members also may deny the existence of the
disease because they do not want to accept the diagnosis and because, at least
in the beginning, AD and other forms of dementia can resemble normal aging.
Therefore additional steps are necessary to confirm or rule out a diagnosis of
dementia.
Physical examination
A physical examination can help rule out treatable causes of dementia and
identify signs of stroke or other disorders that can contribute to dementia. It
can also identify signs of other illnesses, such as heart disease or
kidney
failure, that can overlap with dementia. If a patient is taking medications that
may be causing or contributing to his or her symptoms, the doctor may suggest
stopping or replacing some medications to see if the symptoms go away.
Neurological evaluations
Doctors will perform a neurological examination, looking
at balance, sensory
function, reflexes, and other functions, to identify signs of conditions - for
example movement disorders or stroke - that may affect the patient's diagnosis
or are treatable with drugs.
Cognitive and neuropsychological tests
Doctors use tests that measure memory, language skills, math skills, and
other abilities related to mental functioning to help them diagnose a patient's
condition accurately. For example, people with AD often show changes in
so-called executive functions (such as problem-solving), memory, and the ability
to perform once-automatic tasks.
Doctors often use a test called the Mini-Mental State Examination (MMSE) to
assess cognitive skills in people with suspected dementia. This test examines
orientation, memory, and attention, as well as the ability to name objects,
follow verbal and written commands, write a sentence spontaneously, and copy a
complex shape. Doctors also use a variety of other tests and rating scales to
identify specific types of cognitive problems and abilities.
Brain scans
Doctors may use brain scans to identify strokes, tumors,
or other problems that can cause dementia. Also, cortical atrophy -degeneration of the brain's
cortex (outer layer) -
is common in many forms of dementia and may be visible on a brain scan. The brain's cortex normally appears very wrinkled, with ridges of
tissue (called gyri) separated by "valleys" called sulci. In individuals
with cortical atrophy, the progressive loss of neurons causes the ridges to
become thinner and the sulci to grow wider. As brain cells die, the ventricles
(or fluid-filled cavities in the middle of the brain) expand to fill the available
space, becoming much larger than normal. Brain scans also can identify changes
in the brain's structure and function that suggest AD.
The most common types of brain scans are computed tomographic (CT) scans and
magnetic resonance imaging (MRI). Doctors frequently request a CT scan of the
brain when they are examining a patient with suspected dementia. These scans,
which use X-rays to detect brain structures, can show evidence of brain atrophy,
strokes and transient ischemic attacks (TIAs), changes to the blood vessels, and
other problems such as hydrocephalus and
subdural hematomas. MRI scans use magnetic fields and focused radio waves to
detect hydrogen atoms in tissues
within the body. They can detect the same problems as CT scans but they are
better for identifying certain conditions, such as brain atrophy and damage from
small TIAs.
Doctors also may use electroencephalograms (EEGs) in
people with suspected dementia. In an EEG, electrodes are placed on the scalp
over several parts of the brain in order to detect and record patterns of
electrical activity and check for abnormalities. This electrical activity can
indicate cognitive dysfunction in part or all of the brain. Many patients with moderately severe to
severe AD have abnormal EEGs. An EEG may also be used to detect seizures, which
occur in about 10 percent of AD patients as well as in many other disorders.
EEGs also can help diagnose CJD.
Several other types of brain scans allow researchers to watch the brain as it
functions. These scans, called functional brain imaging, are not often used as
diagnostic tools, but they are important in research and they may ultimately
help identify people with dementia earlier than is currently possible.
Functional brain scans include functional MRI (fMRI), single
photon-emission computed tomography (SPECT), positron emission tomography (PET), and magnetoencephalography (MEG). fMRI uses radio waves
and a strong magnetic field to measure the metabolic changes that take place in
active parts of the brain. SPECT shows the distribution of blood in the brain,
which generally increases with brain activity. PET scans can detect changes in
glucose metabolism, oxygen
metabolism, and blood flow, all of which can reveal abnormalities of brain
function. MEG shows the electromagnetic fields produced by the brain's neuronal
activity.
Laboratory tests
Doctors may use a variety of laboratory tests to help diagnose dementia
and/or rule out other conditions, such as kidney failure, that can contribute to
symptoms. A partial list of these tests includes a complete blood count, blood
glucose test, urinalysis, drug and alcohol tests (toxicology screen),
cerebrospinal fluid analysis (to rule out
specific infections that can affect the brain), and analysis of thyroid and
thyroid-stimulating hormone levels. A
doctor will order only the tests that he or she feels are necessary and/or
likely to improve the accuracy of a diagnosis.
Psychiatric evaluation
A psychiatric evaluation may be obtained to determine if
depression or
another psychiatric disorder may be causing or contributing to a person's
symptoms.
Presymptomatic testing
Testing people before symptoms begin to determine if
they will develop dementia is not possible in most cases. However, in disorders
such as Huntington's where a known gene defect is clearly linked to the risk of
the disease, a genetic test can help identify people who are likely to develop the
disease. Since this type of genetic information can be devastating, people
should carefully consider whether they want to undergo such testing.
Researchers are examining whether a series of simple cognitive tests, such as
matching words with pictures, can predict who will develop dementia. One study
suggested that a combination of a verbal learning test and an
odor-identification test can help identify AD before symptoms become obvious.
Other studies are looking at whether memory tests and brain scans can be useful
indicators of future dementia.
Next: Is There Any Treatment for Dementia? »
- ginkgo (Ginkgo biloba)-oral - Consumer information about the medication GINKGO (Ginkgo biloba) - ORAL , includes side effects, drug interactions, recommended dosages, and storage information. Read more about the prescription drug GINKGO (Ginkgo biloba) - ORAL.
- Complete Blood Count (CBC) - A complete blood count (CBC) measures the concentration of white blood cells, red blood cells, and platelets in the blood and aids in the diagnosis of conditions and diseases such as anemia, malignancies, and immune disorders.
- Lyme Disease - Get the facts on Lyme disease symptoms, signs, causes and transmission (bites from ticks infected with Borrelia burgdorferi), history, diagnosis, treatment and prevention.
Latest Medical News
Alzheimer's RSS