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CHAPTER 5 - IMAGES OF DEMENTIA VS PSEUDODEMENTIA
Alzheimer's Disease Abstracts
Pseudodementia Abstracts
Select a chapter from the list
As the population ages, the incidence of dementia in the U.S. will become an even more
common problem and take up an even larger percentage of the health care budget. With the
advent of new medications that slow the course of some dementing processes, diagnostic
tools that help in the early differential diagnosis of dementia is essential. The SPECT
pattern for Alzheimer's Disease is typically bilateral hypoperfusion in the parietal
and temporal regions of the brain with frontal lobe hypoperfusion occurring later in the
illness. Multi-infarct dementia is characterized by multiple areas of decreased perfusion.
HIV dementia is typically seen by decreased patchy uptake across the cortex. Frontal lobe
dementias (as the name indicates) are often characterized by very poor frontal lobe
perfusion. Psuedodementia (another condition, such as depression, that clinically appears
like dementia) will not have a typical dementia pattern and may be more like a depression
pattern.
Here are several examples of how SPECT can be useful in the evaluation and treatment of
dementia-like presentations.
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Alzheimer's Disease
bilateral decreased parietal and temporal lobe activity |
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When Frank, a wealthy, well-educated man, entered his seventies, he began to grow
forgetful. At first it was over small things, but as time went on the lapses of memory
progressed to the point where he often forgot essential facts of his life: where he lived,
his wife's name and even his own name. His wife and children, not understanding the
change in behavior, were aggravated with his absent-mindedness and often angry at him for
it. Frank's SPECT study showed a marked suppression across the entire brain, but
especially in the frontal lobes, the parietal lobes and temporal lobes. This was a classic
Alzheimer's disease pattern. By showing the family these images and pointing out the
physiological cause of Frank's forgetfulness, in living images, I helped them
understand that he was not trying to be annoying, but had a serious medical problem.
Consequently, instead of blaming him for his memory lapses, they began to show compassion
towards him, and they developed strategies to deal more effectively with the problems of
living with a person who has Alzheimer's Disease. In addition, I placed Frank on new
experimental treatments for Alzheimer's Disease that seemed to slow the progression of
the illness.
Alzheimer's Disease
Here is a scan of a 92 year old man with Alzheimer's Disease who had become forgetful,
frequently lost away from home, forgot how to do simple things such as dress himself and
began getting aggressive with his wife. Notice the extensive frontal lobe
involvement.
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notice marked overall suppression, especially in the parietal
lobes (arrows left images) and temporal lobes (arrows right image) |
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Pseudodementia
good temporal and parietal lobe perfusion, with increased
limbic and/or decreased prefrontal cortex activity |
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Before treatment notice good overall activity, with increased limbic system activity
(center arrow), after treatment with Wellbutrin the limbic system normalizes.
I first met Margaret when she was 68 years old. Her appearance was ragged and unkempt. She
lived alone and her family was worried because she appeared to have symptoms of serious
dementia. They finally admitted her to the psychiatric hospital where I worked after she
nearly burned the house down by leaving a stove burner on. When I consulted with the
family I also found out that Margaret often forgot the names of her own children and
frequently got lost when driving her car. Her driving habits deteriorated to the point
where the Department of Motor Vehicles (DMV) had to take away her license after four minor
accidents in a six month period. At the time when Margaret's family saw me, some
members had had enough and were ready to put her into a supervised living situation. Some
family members, however, were against the idea and wanted her hospitalized for further
evaluation.
While at first glance it may have appeared that Margaret was suffering from
Alzheimer's Disease, the results of her SPECT study showed full activity in her
frontal, parietal and temporal lobes. If she had Alzheimer's Disease, there should
have been evidence of decreased blood flow in those areas. Instead, the only abnormal
activity shown on Margaret's SPECT was in the limbic system at the center of the brain
where the activity was increased. Often, this is a finding in people suffering from
depression. Sometimes in the elderly it can be difficult to distinguish between
Alzheimer's Disease and depression because the symptoms can be similar. Yet with
pseudodementia (depression masquerading as dementia), a person may appear demented, yet
not be at all. This is an important distinction to make because a diagnosis of
Alzheimer's Disease would lead to prescribing a set of coping strategies to the family
and possibly new experimental medications, whereas a diagnosis of some form of depression
would lead to prescribing an aggressive treatment of antidepressant medication for the
patient along with psychother-apy.
Here is another example.
Before treatment notice poor prefrontal cortex activity and increased limbic system
activity, after treatment with imipramine the limbic system normalizes and the prefrontal
cortex improves significantly.
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