Alzheimer's Disease Center
University of California, Davis
The Family Connection
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.
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