Alzheimer's Disease Center
University of California, Davis
The Family Connection
Summer 1998
WHAT IF IT'S NOT ALZHEIMER'S DISEASE?
Dr. William Jagust
Director of the UC Davis Alzheimer's Disease Center
Most patients, families, and physicians are quite focused upon the
diagnosis and care of Alzheimer's disease. Individuals with dementia
symptoms, and those caring for them, consult doctors in order to
diagnose the cause of cognitive decline. Very often a thorough
diagnostic evaluation produces the result that the patient suffers
from Alzheimer's disease. While Alzheimer's disease is not completely
understood, there has been a tremendous amount of new information
generated over the past few years. At this point, we are much better
at making the diagnosis, there are new treatments, and we are
beginning to understand some of the causes. Although there is still a
long way to go in curing Alzheimer's disease, there is considerable
cause for optimism based on these important advances.
On many occasions, after a complete evaluation, the physician makes
the diagnosis of another cause of dementia, rather than Alzheimer's
disease. It has been increasingly recognized that all dementia, even
incurable forms of dementia, are not Alzheimer's disease. At these
times, families become quite concerned, since there is much less
known about these other, non-Alzheimer dementias, and there may be
nowhere to turn for sources of information.
The first, and most important, thing to realize is that if a family
member is diagnosed with a more unusual cause of dementia, much
information and practical advice that is relevant for Alzheimer's
patients and families also applies. The symptoms of dementia are, in
many ways, non specific. That is, the problems of memory loss,
disorientation, language problems and so forth are very similar in
many different dementias. Patients suffering from frontal lobe
dementias, vascular dementias, and Alzheimer's disease often present
families, caregivers, and physicians with similar care and management
problems. Thus, information on the most common dementia, Alzheimer's,
is often very useful no matter what the specific diagnosis.
Nevertheless, families often have specific questions about these
other conditions, so we will provide some information below.
Frontal Lobe Dementia
Frontal Lobe Dementia (FLD), also frequently called
Fronto-Temporal Dementia, is another degenerative brain disease. In
degenerative brain diseases, brain cells die and the brain undergoes
atrophy, or shrinkage. This process occurs throughout the brain in
Alzheimer's disease, but especially in the posterior parts of the
brain, the temporal and parietal lobes. In FLD, the degeneration
predominates in the frontal lobes of the brain. In addition to the
different pattern of brain degeneration, the microscopic appearance
of the brain differs in Alzheimer's disease (AD) and FLD. In FLD, the
characteristic microscopic changes seen in AD - neuritic or amyloid
plaques and neurofibrillary tangles - do not occur. FLD may occur for
between 5 and 10% of all cases of dementia, in contrast to AD which
probably accounts for 60-70%.
Although patients with AD and FLD often appear to have very similar
symptoms, in reality symptoms differ in subtle ways. The frontal
lobes of the brain are particularly important for social
interactions, judgement, and behavior, as well as for language.
Patients with FLD therefore will often demonstrate inappropriate or
embarrassing behavior early in the course of their disease, or they
may become extremely withdrawn or appear depressed. They may also
develop severe language problems early in the course of the disease.
All of these symptoms often occur in conjunction with relatively
preserved memory. Although memory is not normal, it is not as
severely lost as in the early stages of AD. Patients with AD differ
from FLD patients since social interactions and language are often
preserved early in the disease. For example, many AD patients do not
appear to be sick or cognitively impaired early on, since they can
interact very well in many social situations and actually "cover up" their symptoms. These sorts of behaviors are very dependent on the
frontal lobes.
While we do not know the cause of FLD, many cases have been known to
be hereditary. In the past few years, the location of the gene has
been narrowed down to chromosome 17, and scientists are looking
further for the exact location. When the exact gene is discovered,
research will be advanced significantly since the mechanism of how
the disease is caused, and how brain damage occurs, will be better
understood. As of now, there is no specific treatment for FLD.
However, many of the same medications which help treat the behavioral
effects of AD - such as tranquilizers and antidepressants - may be
useful in treating the same sorts of symptoms. Similarly, the same
sorts of behavior management techniques may be useful in managing
difficult behaviors in FLD and AD.
Lewy Body Dementia
Lewy Body Dementia (LBD) was recognized as a relatively common form
of dementia in the early 1990's, so there is still a great deal to be
learned about it. The disease gets its name from unusual deposits in
brain cells, called Lewy bodies. These Lewy bodies have long been
known to occur in Parkinson's disease. However, they have now been
seen frequently in patients who do not have Parkinson's disease, and
they have also been seen accompanying the changes in the brain
associated with Alzheimer's disease. When these Lewy bodies occur in
conjunction with the plaques and tangles characteristic of AD, the
disease is often referred to as the "Lewy body Variant of AD." When
the Lewy bodies occur in isolation, it is often called "Lewy Body
Dementia."
While these brain changes seen under the microscope form the basis
for the diagnosis, clinicians and scientists have been trying to
identify symptoms during life which predict the presence of Lewy
bodies at autopsy. Probably the most reliable symptoms are movement
problems, such as the slowness of motion, rigidity, and tremors which
are characteristic of Parkinson's disease. Another symptom that is
frequently associated with LBD is hallucinations. Nevertheless, these
symptoms are not completely accurate in making the diagnosis, and it
is not yet clear how well most diagnostic guidelines perform in
predicting the presence of Lewy bodies.
As in FLD, there is little known about the cause of dementia with
Lewy Bodies. In some respects, the condition represents an "overlap" between AD and Parkinson's disease. However, this does not really
explain the process since the occurrence of the two problems together
is not a simple chance association. How brain changes can lead
simultaneously to the development of plaques and lewy bodies is
unknown. Similarly, there are no specific treatments for Lewy Body
dementia at this point.
These are two of the more common forms of non-Alzheimer dementias,
and they are important because they may cause diagnostic confusion
for physicians. Why bother to diagnose them? Most importantly, as our
knowledge of dementia improves, we hope that treatments for these
specific causes of dementia will emerge. It is likely that AD, FLD,
and LBD will have different treatments, and if we cannot distinguish
them we will be unable to apply these treatments. Another reason to
make the diagnoses is to be able to explain the nature and causes of
the symptoms to families. For example, families caring for a patient
with FLD may note that the patient's symptoms are not the same as AD
patients, and they may become concerned or alarmed. Explanation of
the precise diagnosis can help alleviate these concerns.