|
Dementia is a brain disorder that affects a person's ability to
think clearly and can impact his or her daily activities. AIDS
dementia complex (ADC) - dementia caused by HIV infection - is
a complicated syndrome made up of different nervous system and
mental symptoms. These symptoms are somewhat common in people
with HIV disease.
The frequency of ADC increases with advancing HIV disease and
as CD4+ cell counts decrease. It is fairly uncommon in people
with early HIV disease, but it's more common in people with severely
weakened immune systems and symptoms of advanced disease. Severe
ADC is almost exclusively seen only in people with
advanced HIV disease.
ADC consists of many conditions that can be of varying degrees
and may progressively worsen. These conditions can easily be mistaken
for symptoms of other common HIV-associated problems including
depression, drug side effects or opportunistic infections that
affect the brain like toxoplasmosis or lymphoma. Symptoms of ADC
may include poor concentration, forgetfulness, loss of short-
or long-term memory, social withdrawal, slowed thinking, short
attention span, irritability, apathy (lack of caring or concern
for oneself or others), weakness, poor coordination, impaired
judgment, problems with vision and personality change.
Because ADC varies so much from person to person, it is poorly
understood and has been reported and described in many conflicting
ways. There are possibly three stages of Dementia:
Possible Symptoms of Early Stage ADC
- Difficulty concentrating
- Difficulty remembering phone numbers or appointments
- Slowed thinking
- Longer time needed to complete complicated tasks
- Reliance on list keeping to help track daily activities
- Mental status tests and other mental capabilities may be normal
- Irritability
- Unsteady gait (walk) or difficulty keeping balance
- Poor hand coordination and change in writing
- Depression
Possible Symptoms of Middle Stage ADC
- Symptoms of motor dysfunction, like muscle weakness
- Poor performance on regular tasks
- More concentration and attention required
- Slow responses and frequently dropping objects
- General feelings of indifference or apathy
- Slowness in normal activities, like eating and writing
- Walking, balance and coordination requires a great deal of
effort
Possible Symptoms of Late Stage ADC
- Loss of bladder or bowel control
- Spastic gait, making walking more difficult
- Loss of initiative or interest
- Withdrawing from life
- Psychosis or mania
- Confinement to bed
What Is ADC?
ADC is characterized by severe changes in four areas: a person's
ability to understand, process and remember information (cognition);
behavior; ability to coordinate muscles and movement (motor coordination);
or emotions (mood). These changes are called ADC when they're
believed to be related to HIV itself rather than other factors
that might cause them, like other brain infections, drug side
effects, etc.
In ADC, cognitive impairment is often characterized by memory
loss, speech problems, inability to concentrate and poor judgment.
Cognitive problems are often the first symptoms a person with
ADC will notice. These include the need to make lists in order
to remember routine tasks or forgetting, in mid-sentence, what
one was talking about.
Behavioral changes in ADC are the least understood and defined.
They can be described as impairments in one's ability to perform
common tasks and activities of daily living. These changes are
found in 30-40% of people with early ADC.
Motor impairment is often characterized by a loss of control
of the bladder; loss of feeling in and loss of control of the
legs; and stiff, awkward or obviously slowed movements. Motor
impairment is not common in early ADC. Early symptoms may include
a change in handwriting. Mood impairments are defined as changes
in emotional responses. In ADC, this impairment is associated
with conditions, such as severe depression, severe personality
changes (psychosis) and, less commonly, intense excitability (mania).
The Symptoms of ADC
Properly diagnosing ADC is heavily dependent on the keen judgment
of doctors, often together with specialists like psychiatric,
brain or neurology experts. It's easy to imagine how difficult
it is to determine impairments in mood and behavior since there's
no standard or common course of ADC. In one person it may be very
mild with periods of varying severity of symptoms. In another
it can be abrupt, severe and progressive. Currently, there is
no way to tell how a person will progress with ADC.
Sometimes symptoms of ADC are overlooked or dismissed by caregivers,
who may believe the symptoms are due to advanced HIV disease.
In fact, people with advanced disease generally do not have symptoms
of ADC but do have fairly normal mental functioning as long as
they also have no other neurological problems. At the other end
of the spectrum, ADC should be carefully distinguished from severe
depression - common among people with HIV that may result in symptoms
similar to ADC.
ADC occurs more commonly in children with HIV than with adults.
It presents similarly and is often more severe and progressive
How Does HIV Cause ADC?
While it is clear that HIV can cause serious nervous system disease,
how it causes ADC is unclear. In general, nervous system and mental
disorders are caused by the death of nerve cells. While HIV does
not directly infect nerve cells, it's thought that HIV can somehow
kill them indirectly. Macrophages -- white cells that are prevalent
in the brain and act as large reservoirs for HIV -- appear to
be HIV's first target in the central nervous system. HIV-infected
macrophages can carry HIV into the brain from the bloodstream.
Test tube studies offer these hypotheses about how macrophages
may help destroy nerve cells:
- An infected macrophage in the brain may shed a particle on
HIV's outer coat (called gp120), causing damage to nerve cells.
- HIV's TAT gene, which helps produce new virus, detaches from
HIV and circulates in the blood, causing toxic effects in nerve
cells.
- The macrophage itself releases a number of substances that,
in excess, can be toxic to the brain. Some examples are quinolinic
acid and nitric oxide, among an array of other signal molecules.
These can bind to nerve cells and cause cell dysfunction or
death. Research has found higher levels of quinolinic acid and
other markers of cell activation in the CSF of people with ADC.
- HIV infection of other brain cells, including astrocytes.
Incidence Anecdotal reports indicate that there are fewer people
with ADC since anti-HIV therapy became standard. People who
develop ADC today tend to
be "sicker" than those who developed it before the
use of anti-HIV therapy. One early study from England supports
this theory.
The British study found that only 2% of people with AIDS taking
AZT developed ADC from 1982-1988, compared to 20% of those not
on AZT. The incidence of ADC dropped from 53% in 1987 (before
the arrival of AZT) to 3% in 1988 (after the arrival of AZT).
Early in the epidemic, many new AIDS cases were attributed to
ADC. These newly-diagnosed people often had ADC but no other AIDS-related
condition. Many doctors report that they are no longer seeing
people who have just ADC. It has increasingly become a disease
of late-stage AIDS when people suffer from multiple infections.
Diagnosing ADC
Three tests are required to diagnose ADC accurately: a mental
status exam, one of the standard scans (CT and/or MRI) and a spinal
tap. These may also help tell ADC apart from other brain disorders
like toxoplasmosis, PML (progressive multifocal leukoencephalopathy)
or lymphoma. Care should be taken, however, as ADC may occur along
with the symptoms of other brain disorders. Diagnosing both conditions
at the same time can be more difficult.
The main way to detect and evaluate ADC is through a mental status
exam. The examination is designed to reveal problems like short-
or long-term memory loss, problems with orientation, concentration
and abstract thinking as well as swings in mood. Imaging of the
brain with scans (like an x-ray) is also used. Certain lab tests
can also be useful like examining cerebrospinal fund (CSF), obtained
by a spinal tap (also called lumbar puncture).
CT and MRI scans are routinely used in the detection of ADC.
CT scans are x-rays that use special beams to produce detailed
images of organs and structures within the body. In people with
ADC these scans usually show signs of destroyed brain tissue.
MRI, or Magnetic Resonance Imaging, is a sensitive brain scan
that is used when CT findings are not conclusive. Results from
both of these tests are helpful in ruling out other causes for
the symptoms.
Tests of CSF may help determine if someone has ADC, but they
are not conclusive. Mostly they're used to rule out other causes
of the symptoms of ADC, and that's why they're important. Many
people with ADC have higher levels of certain proteins or white
blood cells in their CSF. However, not everyone with these levels
turn out to have ADC. Also, people with advanced ADC are generally
more likely to have higher HIV levels in their CSF, although people
with no symptoms of brain disorders sometimes have high HIV levels
in their
CSF.
Data source: AIDS-INDIA eFORUM
|
