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A Review of the Cases Seen at the Clinic |
A review of diagnosed disorders from the current clinical sample of the Adult
Down Syndrome Center supports previous case reports showing reversible disorders,
such as depression, to be a predominant cause of loss of functioning in this
population. Of the 443 adults with Down syndrome seen at the Center, 148
(33%) have presented with a decline in function. Of the 148 with a decline
in function, only 11 individuals (2.5% of the 443 seen) have shown a progressive
and nonreversible decline and deterioration over time, which would merit
the diagnosis of Alzheimer's disease. Several of these 11 initially showed
a reduction in depressive symptoms in response to treatment, but the decline
in function continued and all were later diagnosed with Alzheimer's disease.
For the remaining 137 of the 148 with a decline in function, all have shown
significant improvement, or a return to premorbid state of functioning in
response to treatments, which would not suggest Alzheimer's disease.
Many of the 148 individuals with a decline of function had more than one
health problem that caused or contributed or both to the decline. A mood
disorder was the most commonly diagnosed problem. Seventy-six individuals,
representing 51% of the 148 with a decline of function, were diagnosed with
a mood disorder alone or mood disorder in combination with a second disorder,
which was most often anxiety or obsessive-compulsive disorder. Including
those with a mood disorder, 82 people (55%) had loss of function from a mental
health disorder alone. Of the rest of the 148 who presented with a decline
of function, 42 (28.5%) had a mental health disorder and a medical disorder,
13 (9%) had only a medical disorder (other than Alzheimer's disease), and
11 (7.5%) had Alzheimer's disease. The 148 adults received a total of 247
diagnoses (see Table of diagnoses). Treatment of multiple problems was necessary
in some individuals to achieve improvement or a return to their premorbid
state.
There are a number of additional findings from the Adult Down Syndrome Center
sample that have a bearing on the issue of Alzheimer's disease in Down syndrome.
As shown in this table, the Center sample shows a large number of individuals
who are over the age of 30, who many professionals and caregivers believe
to be at greater risk for Alzheimer's disease. Of these, 307 (69%) adults
were over the age of 30, while 171 (39%) were over the age of 40. This table
shows the diagnosis category of all the adults and for those over 40 who
presented with a loss of function. In our sample, the incidence of Alzheimer's
dementia ranged from seven (6%) for individuals in their 40s, to two (13%)
for individuals over the age of 60 (see this table on breakdown by age).
In the general population, the incidence of Alzheimer's disease ranges from
10% for persons in their mid 60s up to 40% for persons over the age of 80
years. Our sample may not be representative of all persons with Down syndrome;
therefore, we cannot make a broad statement about comparing the prevalence
of Alzheimer's disease in persons with Down syndrome with persons in the
general population.
However, in comparing our population with the general population, it is interesting
to note that our population has a similar rate of Alzheimer's disease, with
an increase in age, except that it appears to occur twenty years earlier.
Our observations also suggest that some people with Down syndrome seem to
age more rapidly as they reach their middle 30s. In many of our adults who
are in their middle 30s, we have observed graying hair, physical slowness
and other changes associated with aging. In addition, the estimated life
expectancy of person with Down syndrome is approximately twenty years less
than the life expectancy for the general population. Therefore, the physical
age of individuals with Down syndrome who are 40 or 50 years of age may be
equivalent to individuals in the general population who are chronologically
60 to 70 years of age. Comparing the prevalence of Alzheimer's disease by
age of our sample with the prevalence in the general population suggests
that the rates may be similar except that the higher rates with age in our
sample occur approximately twenty years earlier. If the prevalence of our
sample is comparable with the prevalence in all persons with Down syndrome,
the higher rates in Down syndrome at any given age may be explainable by
accelerated aging with an earlier onset of Alzheimer's disease. Therefore,
the rate of Alzheimer's disease in persons with Down syndrome should be compared
with the rate for the cohort twenty years older in the general population.
What may be a more compelling finding from the Adult Down Syndrome Center
sample is the incidence of decline for older adults with Down syndrome that
is not attributable to Alzheimer's disease but to other reversible disorders.
For example, for individuals more than 40 years of age in the sample, 53
out of 171 (30.9%) presented with a decline in function (see this table).
Of this group, only 11 individuals out of 53 (21%) showed a pattern of continued
decline and deterioration in functioning suggestive of Alzheimer's disease.
The remaining 42 individuals (79%) with a decline of function were found
to have reversible disorders that were responsive to treatment. In our sample,
if the diagnosis of Alzheimer's disease was given based on an assumption
that all persons with Down syndrome develop Alzheimer's disease rather than
on a thorough evaluation, then more than three-quarters of those that presented
with a decline in function would have received an inappropriate diagnosis
of Alzheimer's disease. The result of this misdiagnosis of an "untreatable
disease" may be to offer no treatment at all or to offer ineffective medications
(such as anti-psychotic medication). In either case, this strategy could
result in an increasing loss of functioning, which is then viewed by the
practitioner as further evidence of Alzheimer's disease.
Some case studies are presented to highlight the importance of the complete
evaluation. For example, a 35 year-old man was seen at his house because
he would not leave his home and rarely left his bed. He would only eat beanies
and had a dramatic decline in function. His thyroid stimulating hormone (TSH)
level was high, and he was diagnosed with hypothyroidism with depression.
He was started on levothyroxine, and an occupational therapist was consulted
to help him become ambulatory again. Over the next year he responded to the
treatment, became ambulatory again, and started going outside.
Another example is a 38 year-old woman who was seen for a decline in function.
The history revealed that she was very independent and came home from work
each day on public transportation. She admitted (and the staff was able to
confirm) that she disembarked from the bus one stop early each day and went
into the local pub for multiple alcoholic drinks. She was diagnosed with
depression probably secondary to her alcohol consumption. With the consent
of her family, the staff was able to change her transportation and she stopped
drinking. Interestingly, she later forgot or denied that she had ever drunk
alcohol, and she is doing well without any evidence of craving alcohol.
In yet another example, we encountered a 43 year-old man who presented with
withdrawal, frequent crying, decline in function, and loss of memory. Within
two to three months his depressive symptoms responded to anti-depressive
medications. However, his memory and decline in function continued on a downhill
course and he developed seizures, gait apraxia and incontinence; and he was
eventually given the diagnosis of probable Alzheimer's disease.
In this last example, a 52 year-old woman was brought by the staff of her
residential facility for evaluation of a decline of function and a concern
that she had Alzheimer's disease. She was losing money, bills that she previously
paid without problem, and other items. The work-up revealed no clear etiology;
however, she did not clearly fit the criteria for Alzheimer's disease. No
diagnosis was given to her, and over the next 18 months there was no further
significant decline. During this time, the carpeting in her room was changed
and in the process the furniture was moved. Staff discovered the missing
money, bills, and other objects neatly packed in small bags and hidden in
many places in her room. She was given the diagnosis of obsessive-compulsive
disorder and started on fluvoxamine (Luvox). Within a few weeks the staff
stated that she was much better at attending to her finances and overall
seemed much improved in her daily functions.
The criteria we use to determine a probable diagnosis of Alzheimer's disease
include progressive decline in function, progressive memory loss, gait apraxia,
incontinence of urine or stool or both, and seizures. While psychological
symptoms often accompany Alzheimer's disease, we avoid making the diagnosis
on the basis of these alone because of the difficulty differentiating between
their etiology and the diagnosis of psychological and behavioral problems.
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