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builds up on artery walls, making the arteries narrower, which then di-
minishes blood fl ow to the brain, or (2) bits of clotted blood block the
inside of arteries, which then prevents blood from reaching the brain—
which, as we noted earlier, produces a stroke. Such clots can cause a se-
ries of small strokes (sometimes referred to as transient ischemic attacks
orministrokes) in which blood supply to parts of the brain is temporarily
blocked, leading to transient impaired cognition or consciousness. When
multiple ministrokes occur over time, dementia can arise as brain areas in-
volved in cognitive functioning become impaired. This form of dementia
can have a gradual onset. In contrast, a single, large stroke infl icts more
brain damage than a series of ministrokes; in such cases, vascular demen-
tia has an abrupt onset.
A clinician makes the diagnosis of vascular dementia based on the
patient’s laboratory test results and on abnormal refl exes or responses
during a neurological examination (for instance, weakness in a limb or
problems in walking). Symptoms of vascular dementia can wax and wane
over a given 24-hour period, but even the patient’s highest level of functioning is
lower than it was before dementia set in (Puente, 2003). In addition, neuroimaging
may reveal lesions in particular brain areas. People with vascular dementia may also
have Alzheimer’s disease, particularly if they are very old (Kalaria & Ballard, 1999).
Vascular dementia is more common in men than women.
The course of the disorder is variable, depending on the specifi c brain areas
affected; when symptoms become more severe, they worsen in a stepwise fashion,
with more defi cits apparent after each instance of reduced blood supply to the brain.
Aggressive treatment of the underlying vascular disease (typically via medication)
may prevent additional strokes or reduced blood fl ow to brain areas.Dementia Due to Other General Medical Conditions
Dementia can also be caused by a variety of other medical conditions, including
Parkinson’s disease, late-stage HIV infection, and Huntington’s disease. With these
and certain other medical conditions, the onset can be gradual or sudden, the course
can range from acute to chronic, and the patient may also develop behavioral
disturbances. Let’s look at some of the general medical conditions that can cause
dementia.Dementia Due to Parkinson’s Disease
Parkinson’s disease is characterized by a slow, progressive loss of motor function;
typical symptoms are trembling hands, a shuffling walk, and muscular rigidity.
About 1 million Americans have Parkinson’s disease, and around 50% of people
with Parkinson’s disease develop dementia due to this disease. Those who develop
dementia are usually older (age of onset is about 65 years old) or are in a more ad-
vanced stage of the disease (Papapetropoulos et al., 2005). The dementia generally
involves problems in memory and executive functions. Comorbid depression can
cause even more cognitive dysfunctions.
Parkinson’s disease causes damage to dopamine-releasing neurons in an area of
the brain known as the substantia nigra. As a consequence, the brains of these patients
do not have normal amounts of this neurotransmitter, which is critically involved in
motor functions as well as executive functions. Parkinson’s disease is thought to arise
from a combination of genetic inheritance and other neurological factors, such as
brain damage caused by exposure to toxins (for example, pesticides).Dementia Due to Lewy Bodies
Another type of progressive dementia is dementia due to Lewy bodies.Lewy bod-
ies consist of a type of protein that, in some people, builds up inside neurons that
produce dopamine and acetylcholine and can eventually cause the neurons to die.
The neurons most often affected are involved in memory and motor control (but
neurons associated with other functions can also be affected).Eye of Science / Photo Researchers
A buildup of plaque in the arteries can lead to
decreased blood supply to the brain, which can
cause vascular dementia.Dementia due to Lewy bodies
A type of progressive dementia caused by a
type of protein (referred to as Lewy bodies)
that builds up inside some types of neurons
and can eventually cause them to die.